A fogging system cools down the surrounding air, which in turn helps the animals cool down and heat escape from their bodies. Cooling the air keeps you from having to drench the animals with cool water, and is an efficient method for lowering the ambient temperature. Setting up fog systems can increase your chickens’ output of eggs and boost the amount of milk your cows produce. Fog vapors can also help dissipate some objectionable odors from pigs, cows and poultry.

Another benefit of using fog systems for animal cooling is that it is less expensive than running conventional air conditioning units, which are not recommended because they can chill your livestock. In addition, fog systems can decrease the amount of insects by providing a different environment less likely for insect breeding. The fog also decreases the amount of dust in the air, further helping to keep your livestock and workers healthy.

For your cattle and pigs, you can install a permanent fog system in the barn, as well as in your horse stables and chicken coops. A high-pressure fog system uses water lines set up overhead, spraying out water droplets through nozzles that immediately turn into a cloud of fog for quick animal cooling. A lower-pressure system would produce a fine mist, which is less efficient than fog.

You can operate your fogger manually, or use the system’s control panel and timer to ensure automatic functioning at your desired temperature and humidity settings to be controlled by sensors and thermostats.

A portable fog system enables you to quickly bring a cooling cloud of moisture droplets wherever you need it, without having to go to the expense of installing a permanent system in your barn or other enclosure. You adjust the water flow rate to achieve lighter or heavier fog, and you adjust the needle valve to set the size of the droplets to your specification and needs. Models are available with different tank capacities, such as a one-gallon unit that you can easily grab and bring into your stable at a moment’s notice. Portable systems can come with timer accessories and turntables, so you can, for example, set it to spray fog through the barn for 60 minutes during an unexpected heat wave to bring relief to your livestock.

As summer approaches, it’s a good time to start making arrangements for cooling your livestock. The animals will be healthier and stay more productive when you keep their environment nice and cool.

Colostrum is a nutrient and immunoglobulin rich fluid that is produced by the ewe shortly before parturition. Besides nutrients and immunoglobulins, colostrum also contains a wide variety of components essential to ensure the survival of a new-born lamb.

Colostrum is critical to lamb survival, insufficient intake of colostrum is a major cause of neonatal fatalities.

A lamb requires between 180-290ml of colostrum per kilogram of body weight, this means each lamb requires over a litre (based on an average birthing weight of 5-6kg) of colostrum. Colostrum requires a lot of investment, energy-wise by the ewe so if she gives birth to multiple offspring, it can be very demanding to keep up with the amount of colostrum required by her lambs. For maximum efficacy, new born lambs must consume the required amount of colostrum within the first 18 hours of life, putting even more pressure on the ewe.

A study by McNeill et al. showed that ewes bearing twin-lambs failed to provide enough colostrum in 30% of cases, whilst ewes bearing only a single lamb failed to produce enough colostrum in 10% of cases.

Why Is Colostrum Important?

Colostrum is important for two main reasons:

1. It provides the new born lamb with a rich energy source to allow them to maintain homeostasis and survive
2. It provides the lamb with maternally derived antibodies that help fight off infections while the lamb builds its own, stable immune system

Maternally Derived Antibodies

The immune system of a new born lamb can take some time to develop, if the immune system is required to respond to a pathogen – it can take some time to produce the required antibodies to defend the new born.

Because of this, the mother supplies immunological assistance in the form of antibodies. In some species, antibodies can be transferred via the placenta – this is not the case for sheep or other ruminants. This means, all maternally derived antibodies must be obtained from the colostrum, again highlighting the importance than a new born lamb receives upwards of a litre of colostrum.

If a lamb does not receive enough colostrum, they may not be able to adequately respond to an immunological threat.

The maternally derived antibodies can provide protection for the new born for a number of weeks.

It is imperative that the lamb receives colostrum as soon as possible; this is because there is only a short window of opportunity (<24 hours following birth) where the intestines are able to absorb the immunoglobulins from the mother’s colostrum. After this period, the digestive enzymes of the stomach would destroy any ingested colostrum.

Dealing with Colostrum Deficiencies

There are no specific signs that a new born lamb may have not received enough colostrum. General fatigue, lethargy and muscle weakness could indicate a deficiency. Of greater concern is the fact that, without enough colostrum, the new born could succumb to a plethora of bacteria diseases.

Time is of the essence when it comes to dealing with colostrum deficiency because, as mentioned earlier, there is only a window of around 18 hours to react. After this time it will become difficult for the new born to take on enough antibodies from the mother’s colostrum to provide a healthy immune system.

There are a number of methods to dealing with deficiency:

If noticed early:

• The lamb can be given colostrum from another ewe (sometimes colostrum is stored in the freezer, ready to defrost in emergencies – this does reduce the efficacy of the colostrum however)
• The lamb could be given a high quality lamb colostrum supplement that mimics the mother’s colostrum – being both rich in energy and containing the required immunoglobulins.

If noticed late:

• Antibodies (obtained from the plasma of the mother) could be given intravenously
• Broad spectrum antibiotics could be administered for the first few weeks of the new born’s life, to help fight off infections

Adapted from Nowak R., Poindron P. (2006) From birth to colostrum: early steps leading to lamb survival. Reprod. Nutr. Dev. Vol. 46 pgs. 431 – 446

McNeill D, Murphy PM, Purvis IW. (1988) Lactogenesis and colostrum production in ewes. Proc Aust Soc Anim Prod, 17: 437.

Free Resources for Vet Students:

VIN.com – Vet students will find an enormous amount of information at the Veterinary Information Network (VIN) site, and throughout the course of their academic careers, they can access it for free. Featured here are thousands of medical journals, conference presentation notes, and even message boards for students who wish to communicate with and learn from working professionals out in the field. The site also hosts its own Student Center, a database of resources aimed specifically at students of veterinary medicine.

VetVideos.com – This comprehensive collection of educational videos presented by Dr. Rajesh Banga covers nearly every subject relevant to veterinary medicine, making it a valuable resource for students to have on hand. Lecture-style videos cover medicals sciences, while actual demonstration videos focus on office examinations, vaccinations, surgical preparation, surgical procedures, and much more.

Vet.com – Although this site was designed for both pet owners and pet care professionals alike, it features a very informative section specifically geared towards vet students. Here they will find links to top vet universities, a place for job postings, and a list of online resources that students might find helpful throughout the course of their studies.

Companion Animal Parasite Council (CAPC) – The goal of this site if to keep veterinarians and pet owners on the same page when it comes to parasite prevention and management in the animals under their care. There are lots of resources here, and students can find information on a variety of internal and external parasites, a library of articles on parasite management, parasite incident maps, and even a downloadable study guide on parasitology.

American Veterinary Medical Association (AVMA) – This leading site is the go-to place for some of the best resources in veterinary medicine found on the web today. Here students will find up-to-date medical news and extensive collections of AVMA journals, as well as information on AVMA advocacy, animal welfare, animal and public health issues, education, careers, and more.

Veterinary Emergency Drug Calculator – Vet students can use this handy emergency drug calculator to determine appropriate drug dosages for dogs and cats in emergency situations. Simply type in the animal’s body weight and click the “calculate” button. After making calculations, the drug dosage form can be printed out and stored for future reference in the file of the animal being treated.

FDA – The U.S. Food and Drug Administration website is an excellent resource for students going into the field of veterinary medicine. It offers plenty of information on drug development and approval, safety policies and procedures, approved and unapproved animal drugs, and pet product recalls. This site also hosts a section about the Center for Veterinary Medicine, where students can locate potential internship opportunities.

International Veterinary Information Service (IVIS) – This site offers veterinarians and vet students a wealth of free resources including eBooks, veterinary meeting notes, journals, mini-courses, and a calendar of special veterinary medicine events and save-the-dates.

Veterinary Practice News – Here you can keep up with the latest news and developments in veterinary medicine, up-and coming products, and other industry issues. Every month the site showcases a different vet school in a special section called “Vet School Spotlight,” which might be of particular interest to students.

PetMD – Students will find plenty of reference materials and resources on this user-friendly site including an extensive list of animal diseases, a quick symptom checker, lots of animal care tips, a glossary of veterinary medical terms, emergency care information, a library of animal health articles, current veterinary news, a guide to animal breeds, and so much more.

Guest post from Pat Singer. Pat writes about accredited online universities for AccreditedOnlineColleges.com

Many of us know copper as the ductile metal, but it is also a vital chemical element for life. Copper (Cu) is vital due to its multiple biological roles in the body, from electron transport to metalloproteins. Because of the imperative role that copper plays, both humans and other mammals (such as cattle) need to consume trace amounts of copper in the diet. Humans, for example, need to consume between 1 to 3mg of copper a day otherwise a copper deficiency can develop

Hypocuprosis is the term used to describe an unusually low level of copper in the blood and plasma. Continued hypocuprosis will lead to a deficiency of copper in the body, which can serious health consequences.

Copper facilitates the uptake of iron and so a deficiency of copper can produce, amongst other problems, anaemia-like symptoms.

A deficiency in copper will also lead to the malfunction of metalloenzymes,  these enzymes have an important antioxidant role in the body, protecting DNA from free-radical damage.

Copper Deficiency in Cattle

Hypocuprosis is more common in grazing cattle than might be expected. At one point, copper deficiency in US beef cattle reached over 40%.

It can often be difficult to detect a copper deficiency in cattle due to the wide array of symptoms caused by the deficiency. On a farm it is unlikely that one cow will be affected, as the problem will likely be due to the nutritional composition of their feed.

Some symptoms of copper deficiency in cattle are:

• Pale coat
• Anaemia
• Bone fractures/weak bones
• Reduced fertility
• Decreased immune resistance
• Diarrhoea
• General ill-health

All these symptoms can contribute to an economic loss for the herd owner.

There is also strong correlation between hypocuprosis and abortion in cattle. A recent study found that 87% of aborting cattle were copper deficient (Sakhaee 2011). A calf born from a copper deficient cow is much more likely to suffer from hypomyelination of the spinal cord – a condition which can cause muscle tremors, ataxia and paralysis.

Diagnosing a Copper Deficiency

A copper deficiency can be difficult to diagnose, as there are many differential diagnoses. The only true way to diagnose a deficiency is to analyse the levels of copper in the blood and blood plasma. Sometimes, the level of copper in the liver is also measured as hypocuprosis is observed in the liver before the blood (diagnosis from liver plasma is more expensive however).

There are essentially two ways to diagnose a copper deficiency, either by blood analysis (to detect if the blood is low in copper) or by nutritional analysis (to detect if the diet is low in copper).

If a farmer or herd owner believes their cattle may be suffering from a copper deficiency there is a method they can use themselves to determine whether or not this is the case. By selectively treating a small group of cattle, the farmer can monitor changes in their health. If the selected group appears to recover and the remainder of the herd continues to suffer with copper deficiency symptoms or general ill health it can be concluded that a copper deficiency is the root of the problem. See below for how to treat a copper deficiency.

Treating a Copper Deficiency

There is essentially only one way to treat a copper deficiency – increase copper intake! In more severe cases, copper solutions can be injected to rapidly raise blood plasma Cu levels. In most cases however, a commercially available dietary copper supplement can be added to the feed. This will ensure the cattle are meeting their required daily intake of dietary copper.

To prevent future instances of copper deficiency, the farmer could either choose to continue supplementing the poor quality feed with a copper supplement or increase the quality of feed. In certain high yield dairy herds, it may be impossible to meet nutritional demands, especially post-parturition therefore supplementation may be a necessity.

When using a copper supplement, be cautious of copper toxicity – farmers are supplementing feed with increasingly higher levels of copper and as such copper toxicity is on the rise.

Like copper deficiency, copper toxicity can be difficult to diagnose and can be fatal. Clinical signs to be aware of include:

• Colic
• Reduced appetite or milk yield
• Blood cells in the urine, giving it a dark red appearance

References

Sakhaee, E., Kazeminia, S. Relationship between liver and blood plasma copper level and abortion in cattle (2011) Comparative Clinical Pathology, 20 (5), pp. 467-469.

Glaucoma is an eye disease which can affect both humans, dogs and many other mammals. It is characterised by optic nerve damage and loss of peripheral vision. In the vast majority of Glaucoma conditions the nerve damage is caused by rising pressure within the eye, so called intraocular pressure (IOP). The pressure within our eye is continually maintained through a balance of the amount of fluid being produced and the amount of fluid draining out of the eye. Providing these two elements balance each other out, then the intra ocular pressure remains stable. There are a number of different types of Glaucoma and these generally relate to how the pressure within the eye changes and the most common types are as follows:

Primary Open Angle Glaucoma:

This is by far the most common type of Glaucoma and is characterised by asymptomatic build-up of pressure within the eye. It is increasingly common as we get older and is generally caused by a reduced outflow of the fluid within our eyes. As I stated above, aqueous humour (eye fluid) is continually being produced and then drained from the eye. It is drained through a sieve like meshwork called the Trabecular meshwork. With age this structure can become thickened and small blockages can occur, meaning the fluid cannot drain away as well. As this progresses over time, the eye pressure slowly increases until it gets to the point where it starts damaging the optic nerve. Damage to the optic nerve leads to a slow loss of peripheral vision which again is generally not noticed until it gets quite extensive. The typical treatment for open angle Glaucoma is eye drops which are instilled daily and help keep the eye pressure at a normal level. In the rare cases that eye drops do not work, you will have to have to have either Glaucoma eye surgery or laser eye treatment.

Closed Angle Glaucoma:

This is a rare type of Glaucoma and is characterised by a rapid increase in eye pressure. Unlike open angle Glaucoma the symptoms of closed angle Glaucoma are extreme and you are likely to be in considerable pain, which comes on suddenly. Closed angle Glaucoma is not caused by a blockage in the trabecular meshwork as is in open angle Glaucoma. The blockage occurs between the iris and the cornea and is considered an ocular emergency as the pressure can rise to dangerous levels. If you suffer from this Glaucoma you will need to see an ophthalmologist as soon as possible, who will administer an injection in to your eye to rapidly reduce the pressure. Once the pressure has been reduced to a safe level your surgeon will have to perform laser treatment of your iris to prevent the blockage from occurring again.

Normal Tension Glaucoma:

This type of Glaucoma is the most difficult to detect as there is optic nerve damage in the absence of increased pressure. The exact causes are not known but it is thought that it is related to a decreased blood flow to the optic nerve. Treatment is more difficult with this type of glaucoma but it usually involves using similar eye drops that are used to treat open angle glaucoma.

Canine Glaucoma:

Canine Glaucomas can often go unnoticed until they reach a severe state, this is due to a lack of clinical symptoms. This highlights the importance of regular eye examinations by qualified veterinarians. The only clinical symptoms of canine Glaucoma are that the dog may rub the eye if it is painful. An affected eye may also be red, swollen, sore, or become clouded in appearance.

Predisposed breeds include:

• Cocker Spaniels
• Poodles
• Beagles
• Chow-Chows
• Jack Russell Terriers
• Bassett Hounds
• Dalmatians

This is not to say that primary Glaucomas have not been observed in other breeds, nor is it to say that the above breeds will definitely develop a Glaucoma – just that their genetics make them more likely to develop.

Diagnosis & Treatment

There are three primary methods used by veterinarians of diagnosing Glaucomas; tonometry (measurement of IOP), gonioscopy (Examination of the angle in the anterior chamber) and ophthalmoscopy (evaluation of the retina and optic nerve).

Treatment is similar to that given to humans; laser surgery (to selectively destroy tissue), enucleation (removal of the eye), intra-ocular evisceration & implantation (removal of the inner contents of the eye – the outer portion remains) and shunts (a method to remove pressure from the eye).

Conclusions

Glaucoma is generally considered the silent disease (excluding closed angle glaucoma) as most people who have the condition are completely unaware. Having regular eye tests is the only real way of detecting the condition and providing it is picked up early enough it can generally be treated or controlled to the point that it will never affect your vision. During an eye test your optometrist will assess the health of your optic nerves, measure your intraocular pressure and check your peripheral vision. If any of these are found to be suspicious you will be referred to a glaucoma specialist.

This article was written by an Optometrist, Tim Harwood who has over 10 years’ experience of screening people for Glaucoma. He also writes the content for his own website Treatment Saver which helps people make the right decision about their health which includes a laser eye surgery forum and many well written guides. As an optometrist, Tim is a passionate about encouraging people to get their eyes tested regularly, regardless of whether they think they having any problems or not. Glaucoma is after all the silent disease!

Benign prostatic hyperplasia (BPH) involves the formation of nodules on the prostate that compress the urethral canal. BPH is a natural consequence of aging that affects older dogs. Entire male dogs (i.e. not castrated) over the age of 5 have an 80% chance of suffering from BPH to some extent.

Fortunately, BPH is not a fatal or threatening condition and is easily treated; yet due to the lack of clinical signs in the majority of cases, BPH can often go undetected. This can cause discomfort for the patient. Whilst there may not be any direct risk posed by BPH, it has been suggested that it may dispose the patient to increased risk of urinary tract infections.

BPH can result in painful urination, frequent urination or hesitancy to urinate; yet these symptoms may not be immediately obvious. Because of the ease at which BPH can be treated and the high prevalence rate in elder males it is worth asking for a screening from your vet if your dog is in the ‘at risk’ category (non-castrated males over the age of five).

The Canine Prostate

The canine prostate and the diseases that affect it are comparable to the human prostate. As such, it has been subject to numerous studies.

The prostate is the only major accessory sex gland in the male dog – an accessory gland being any organ other than the gonads that contribute to sexual function. The prostate is located entirely within the pelvic cavity of a young dog, however as the male ages, the prostate adopts a more abdominal position. As the male ages, the size of the prostate increase, further contributing to the relocation of the prostate.

The canine prostate secretes a fluid that makes up a major part of the male ejaculate; this fluid facilitates sperm transportation by reducing the viscosity of the ejaculate. Due to the acidic nature of this fluid, it is also suggested that it reduces the likelihood of urinary tract infections developing. The acidic environment will make the urinary tract less hospitable to bacteria.

Growth of the canine prostate is influenced by the release of testosterone. The continued release is believed to be responsible for the spontaneous enlargement of the prostate associated with BPH.

Diseases of the Prostate

Benign Prostatic Hyperplasia

The most common canine prostatic disease, BPH, arises spontaneously as a consequence of ageing and endocrine influence. Testosterone (produced by the testes) is converted by the enzyme 5-α reductase to dihydrotestosterone (DHT) in prostatic epithelial cells. DHT is believed to be the predominant factor in promoting BPH.

BPH can be permanently prevented by castration due to the reduction in testosterone production.

Squamous Metaplasia 

Squamous metaplasia is the abnormal change in tissue whereby the epithelial cells become squamous (flattened). Whilst squamous metaplasia doesn’t signify disease, it does show that the body may be experiencing stress or suffering from an irritation.

However, squamous metaplasia may lead to the development of cysts or abscesses that can obstruct the urethra. This can be detected by an increased number of squamous cells in prostatic fluids. The lesion is reversible but usually involves castration.

Neoplasia

Primary neoplasia contributes for around 5% of all canine prostatic diseases. Neoplasia is new, abnormal tissue growth – with prostatic adenocarcinoma (PAC or prostate cancer) being the most common form of neoplasia.

Neoplastic growths on the prostate gland are typically enlarged asymmetries that can put pressure on surrounding organs. Unfortunately PAC can be difficult to diagnose early, meaning treatment often lacks efficacy.

Prostatic Cysts

Cysts can arise either as small-yet-multiple nodules within or around the prostate or as larger, single ‘true cysts’ that are fluid filled and have a distinct cavity wall. Cystic prostate glands will feel enlarged and asymmetrical upon palpation, however many cases show no clinical signs. Larger cysts can prove quite stressful, putting pressure on abdominal organs and posing the risk of infection.

Treatment usually involves draining the cyst, removal of the cystic tissue or in more severe cases – removal of part or the entire prostate.

Prostatitis

Prostatitis is the inflammation of the tissue of the prostate gland. As the body attempts to fight off infection, irritation of the surrounding tissue is likely. Inflammation of the prostate is typically caused by bacteria and can prove painful for the patient. Treatment involves the administration of antibiotics.

Clinical Signs of Canine Benign Prostatic Hyperplasia

The main pathology of BPH is the enlargement of the prostate. This enlargement puts pressure on neighbouring organs and the urethral tract resulting in a number of possible clinical signs:

• Pain induced lameness
• Difficulty in defaecation or urination
• Abdominal pain
• Haemorrhagic discharge from the urethra
• Ribbon-like faeces

However it is more likely is that the dog will display no clinical signs of BPH – adding to the argument that dogs in the ‘at risk’ category should be screened with or without display of clinical signs.

A dog displaying BPH induced lameness may be incorrectly diagnosed with orthopaedic disorders particularly of the hips or spine.

Screening for Canine Benign Prostatic Hyperplasia

When presented with a patient believed to be suffering from BPH, the traditional method of diagnosis is rectal palpation. This allows the size of the prostate to be determined. Dogs suffering from BPH will be suffering from an enlarged yet symmetrical prostate that can be detected by palpation.

The problem with rectal palpation is that diagnosis is subjective i.e. dependent on the experience of the person performing the palpation. The experience can also prove uncomfortable for the patient.

A less invasive method of screening for BPH is the use of ELISA tests. Blood is taken from the patient, which is then subject to an ELISA test. ELISA tests are able to detect specific enzymes or proteins in a sample fluid.

The BPH specific ELISA detects levels of the canine prostate-specific arginine esterase, an enzyme whose concentration can be linked to the size of the prostate. A high level of arginine esterase is a strong indicator of BPH.

The ease at which an ELISA test can be run for BPH gives confidence that it could be easily incorporated in to routine blood tests (such as those performed on elderly patients for liver disease or chronic renal failure). This would allow diagnosis of BPH in patients where clinical signs were not apparent.

A positive diagnosis of BPH should be followed up with ultrasound. Ultrasound can quickly and easily confirm a diagnosis – an enlarged, symmetrical prostate can be located easily and will appear clearly on the monitor. The prostate will not appear homogenous and vary in density. Whilst examining the prostate via ultrasound, it is also easy to detect for secondary abscesses or cysts.

Treatment of Canine Benign Prostatic Hyperplasia

Because enlargement of the prostate is almost entirely dependent on the production of high testosterone levels, castration can provide permanent relief from BPH.

Another traditional treatment involves the use of progestagens, which are hormones, produced predominately by the female – large amounts of progestagens are released by the corpus luteum. Progestagens decrease the level of luteinizing hormone which has an antiandrogenic effect on the male i.e. it reduces the amount of androgens in the body which are the hormones responsible for the development of the male sex organs.

There may be cases where castration is not an option, in which case the use of pharmaceuticals is recommended. There are two main pharmaceutical treatments that can be used to rapidly reduce the size of the prostate – osaterone acetate and finasteride.

Finasteride blocks the action of the enzyme 5- α testosterone reductase thus reducing levels of DHT – the compound primary responsible for enlargement of the prostate. Finasteride does not reduce semen quality, libido or fertility – but if the administration of the drug is discontinued, the prostatic hypertrophy (BPH) will return.

Osaterone acetate provides a more rapid reduction in prostate size (40% reduction in 2 weeks). The drug works by blocking the effects of testosterone in the prostate, leaving blood testosterone levels unchanged. The advantage of this is there is no reduction in reproductive quality.

The use of osaterone acetate can be combined with castration to provide rapid and permanent relief from BPH.

Magnetic resonance imaging or MRI is a medical imaging technique which can be utilised to visualise internal structures with relatively great detail. Magnetic resonance scanners generate strong magnetic fields which pulse and cause individual nuclei of atoms within the body to spin. Gradients in the strength of the magnetic field causes different nuclei to spin at different speeds. Powerful 3D imaging software is able to translate these variances in spin in to a visual interpretation of the body. The result is a 3D image (viewed in cross-sections) that provides great contrast between the soft tissues of the body. This makes MRI an important tool in veterinary imaging.

Pathologies will alter the properties of tissue, resulting in the production of a different image to healthy tissue. This is why MRI is becoming increasing popular as a diagnostic tool; especially for heart, brain and muscle diseases, as these are tissues which would typically be difficult to image with traditional methods such as X-rays or computed tomography (CT). Another benefit of MRI is that, unlike X-rays and CT scans, MRI does not use ionizing radiation to create an image.

Clinical veterinary MRI started around 25 years ago, with veterinary institutions installing their own scanners during the 1990s. Initial MR scanners had low strength magnetic fields coupled with basic software, they were also extremely expensive.

Clinical uses for the early MR scanners mainly involved the scanning of the canine head and brain, however as MR scanners have become more common place, their applications in veterinary practices have become more widespread. Scanners are now increasingly used for spinal and orthopedic conditions as well as central nervous system disorders and the diagnosis of joint diseases such as osteoarthritis.

Types of MRI Scanners Used in Practice

MRI scanners are typically either high or low strength. Low strength scanners are open field and do not fully enclose the patient whilst high strength scanners are closed field and thus require full enclosure of the patient.

Open field scanners have become increasingly popular due to their flexibility in design, smaller size and the lower price tag. Closed field scanners however provide greater quality images with stronger contrast of soft tissues – making them more adept at distinguishing smaller details.

The increased strength of closed field scanners comes at a price as they require a stronger magnetic field to operate with greater detail. Closed field scanners operate at 1.5 Tesla, that’s 7.5x as powerful as open field scanners (0.2 Tesla) and a massive 2.5 million times as strong as the magnetic field of the Earth (0.000006 Tesla).

Open field scanners may not provide the detail which closed field scanners can, but they can be extremely useful in situations where it would be near impossible to get the patient into an enclosed MR scanner. For example, it can prove a great technical difficulty to get a horse in to an enclosed MR scanner, as such a ‘standing MRI’ system has been developed. This system eradicates the need for general anaesthesia and increases the ease at which MRI can be preformed.

Applications of MRI

MRI is a powerful diagnostic tool and as such one of the most common applications of MR scanning in practice is the diagnosis of disease or injury such as spinal injuries, investigation of central nervous system abnormalities and the diagnosis of neoplastic diseases (tumours). In the equine world MRI is becoming increasingly useful in diagnosing the possible causes of lameness.

Other applications include:

• Diagnosis of soft tissue injuries such as damaged ligaments
• Joint injuries such as osteoarthritis
• Injury or disease of internal organs such as the brain, heart or digestive organs

Note: MRI cannot provide detailed images of bones and as such X-ray remains the most popular tool for investigating damage to bones

Symptoms which may prompt recommendation for an MRI scan include:

• Seizures
• Depression
• Aggression
• Behavioural changes
• Paralysis of limbs
• Spinal pain
• Visible distress caused by the limbs or joints

MRI in Practice

MR scanning typically requires that the patient undergoes general anaesthesia, this ensures that the patient remains still during the often noisy and lengthy procedure. Considering some procedures can last upwards of an hour the importance of anaesthesia becomes clear. It is imperative that the patient remains still to produce clear and detailed final images. Failure to produce clear images will hinder the diagnostic process and may create the need for another scan.

Because MR scanners can produce unwanted heat, this is compensated for by increasing the circulation of cool air. As such, patient body temperature can decrease. It is therefore often necessary to provide wraps or blankets to keep body temperature up and reduce the risk of hypothermia. Conversely, the powerful radio transmission required to spin atoms may, in some conditions, heat the body to a point of hyperthermia.

During a scan, the rapid switching of the magnetic field between the on and off state can cause nerve stimulation. Stimulation can cause twitching of limbs, but poses no danger.

The condition of the patient prior to the scan is another factor to take in to account, for example, patients with spinal injuries will require extra attention during movement to and from the scanner. As MRI is often used for investigating the brain, the use of general anaesthesia must also be carefully considered. For example brain pathologies may alter how the respiratory system reacts to anaesthesia.

MR scanners can produce a large amount of noise reaching levels of up to 120dB, fortunately, animals are typically anaethetised and therefore not subject to these harsh noise levels. Staff on the other hand may wish to use ear protection.

As MR scanning is a non-invasive procedure, no special aftercare is required other than the typical care provided following the administration of general anaesthesia.

MRI Safety

MR scanners produce strong magnetic fields and as such can pose a number of dangers. The large magnets used in closed field scanners are superconductors that require cooling by liquid hydrogen. These superconductors cannot be turned off except for under exceptional circumstances, this is due to the fact that the shutting down process (quenching) involves the venting of helium which poses an asphyxiation risk.

Whilst running, the strong magnetic field produced by MR scanners can attract metal items with lethal force – even larger metal items such as tables and trollies. As such staff must take extreme care to ensure that patients and the staff themselves are free from magnetic metals.

Staff should be fully briefed on MRI safety and appropriate warnings should be in place in practices with MR scanning units, however more information on MRI safety can be found here.

Cognition is defined as; the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses. As we age our cognitive ability declines naturally, however some individuals may experience a rate of decline much greater than expected. This is known as cognitive dysfunction.

Cognitive dysfunction is apparent in a number of species, including; humans, dogs and cats. In dogs, canine cognitive dysfunction (CCD) can be responsible for alterations in normal behaviour, for example, the dog may be less active or show changes in their social interactions with human family members.

CCD is more likely to affect older dogs (just as human cognitive dysfunction, also known as dementia, is more likely to affect older individuals). The clinical signs of CCD can start to develop from 8 years of age, with the likelihood of developing CCD increasing with age. In a study by Neilson et al which looked at male and female dogs aged between 11 to 16, 28% of dogs aged 11 to 12 were diagnosed with mild CCD, whilst 10% were diagnosed with severe CCD. In the 15 to 16 year age bracket this increased to a 68% diagnosis rate for mild CCD and a 35% diagnosis rate for severe CCD.

Clinical Signs of Cognitive Dysfunction in Dogs

The initial signs of CCD can be very mild and thus easy to miss, however the symptoms will gradually develop over time. As the clinical signs can become apparent from as early as eight years of age, it is vital that you begin to regularly monitor your dog’s cognitive function by completing behavioural questionnaires. These questionnaires will be available from your vet. Using a questionnaire will allow for early diagnosis of CCD and thus prompt intervention.

The clinical signs of CCD typically fall in to the following categories, mainly associated with memory and learning:

• Activity e.g.Increased or decreased movement, restlessness or wandering
• Disorientation e.g. Decreased recognition of familiar people, pets or places
• Interaction Changes e.g. Decreased interest in interaction or play
• Sleep Pattern Alterations e.g. Restless sleep, crepuscular (dawn/dusk) sleeping activity
• Loss of House Training e.g. Increased house soiling, or no signal of wanting to go outdoors

If a dog is displaying any abnormalities in the above categories, it is worth visiting your vet to rule out any differential diagnoses. For example, if your dog is displaying decreased activity it might not be CCD but instead something such as osteoarthritis. However, whilst it is important to rule out differential diagnoses, it is possible for CCD to coexist with other diseases.

Pathology of Canine Cognitive Dysfunction

Cognitive dysfunction is a reduction in the mental ability of an individual beyond what is expected for that age. There are a number of factors which can cause this decrease in cognitive function:

• Increased oxidative damage of brain tissue by free radicals, correlated with a decrease in antioxidant levels
• Development of ß-amyloid plaques in the cortical regions of the brain
• Impaired glucose metabolism in the brain
• Decreased frontal lobe volume

Dogs with CCD also show reduced cerebral blood flow and reduced dopamine levels in the brain.

Free radicals are harmful chemicals produced on a daily basis by the body. As dogs age, the amount of free radicals produced increases but the amount of antioxidants (free radical neutralising molecules) decreases. An Increased level of free radicals leads to increased amounts of cellular injury and decreased glucose metabolism by neurones.

Unregulated free radicals can react with mitochondria, DNA, lipids and proteins resulting in alterations to enzymes, receptors and ion channels, organelle loss and eventually apoptosis (Montuschi, P 2007). The mitochondria are essential for neuronal defence and repair (Liu, J 2008), damage to them leads to impaired electron transport, decreased energy production and increased production of free radicals resulting in an escalating cycle of destruction (Wei, YH 1998).

Neuropathology of Canine Cognitive Dysfunction

Different structures in the brain undergo different aging processes:

• Meninges become thick and calcified (Osella, MC 2008)
• Blood vessels become harder (arteriosclerosis) and show decreased perfusion (Milgram, NW 2004). There is also increased likelihood of haemorrhage surrounding the blood vessels (perivascular haemorrhage) (Landsberg, GM 2010).
• Ventricles become dilated (Osella, MC 2008).
• Neurones and glial cells demyelinate (Hu, YS 2010; Hill, AS 2004), their membrane function alters and they are more likely to undergo apoptosis. The axon structure undergoes degeneration and fatty deposits (lipofuscin) build up on the neurons (Salvin HE 2010).
• Neurotransmitters and receptors decrease in abundance.

Treating Canine Cognitive Dysfunction

Treating CCD often involves a three-pronged approached; utilising pharmaceuticals and nutraceuticals and combining them with mental and behavioural support.

Pharmaceuticals

Selegiline Hydrochloride is the only licensed drug available for treatment of CCD. It is a selective, irreversible inhibitor of monoamine oxidase B (MAO-B). Because MAO-B is responsible for the metabolism of dopamine, its inhibition by Selegiline increases dopamine concentrations. Selegiline Hydrochloride has also been shown to reduce glial cell damage, promote synthesis of nerve growth factors and to a minor extent, reduce free radical damage.

There are side effects associated with selegiline hydrochloride use however. Due to the fact selegiline is metabolised to L-amphetamine and L-methamphetamine it shares similar side effects with these sympathomimetic stimulants.

Side effects range from minor dizziness and nausea to more serve heart arrhythmia and respiratory difficulties.

Nutraceuticals  

Treating CCD is a long term process and many people can be concerned with continually administering pharmaceuticals to their pets. As an alternative to pharmaceuticals, many owners are turning to nutraceuticals such as AKTIVAIT^® from VetPlus. AKTIVAIT^® is a synergistic combination of nutrients, antioxidants and mitochondrial co-factors which has been demonstrated to be of benefit for cognitive dysfunction (Heath, Sarah 2007). AKTIVAIT^® is available to treat both canine and feline cognitive dysfunctions.

How AKTIVAIT^® Works

AKTIVAIT^® contains a number of ingredients which act together synergistically to alleviate CCD. Ingredients include:

• Docosahexaenoic Acid (DHA) – Reduces neuronal inflammation and apoptosis. DHA is also responsible for increasing neuronal levels of phosphatidylserine
• N-Acetyl Cysteine (NAC) - A primary precursor to glutathione a crucial endogenous antioxidant which protects neurones from oxidative damage. NAC levels decrease significantly with age
• L-Carnitine & Acetyl L-Carnitine - Essential in the transport of long chain fatty acids. L-Carnitine enhances mitochondrial function whilst Acetyl L-Carnitine acts synergistically with α-lipoic acid to improve brain function, memory and activity levels by helping to reduce mitochondrial damage and increase mitochondrial numbers
• Phosphatidylserine – Regulates the fluidity of neuronal membranes. It enhances transmembrane transport, ion channel function and enhances neurotransmitter release. Phosphatidylserine also protects cholinergic neurons and pyramid cells of the hippocampus from apoptosis and loss of dendritic spine. It also increases nerve growth factor synthesis and release, thus stimulating neuron sprouting and growth. Phosphatidylserine stands out as an essential brain nutrient (Osella, MC 2008).
• Coenzyme Q₁₀ – A lipid soluble antioxidant which helps to maintain antioxidant defences by regenerating vitamin E. Coenzyme Q₁₀ is essential for electron transport in the mitochondria, while deficiency impairs ATP production and leads to oxidative stress. Supplementation with Coenzyme Q₁₀ has been shown to delay brain atrophy and to protect against cognitive decline.
• Selenium – An antioxidant which can help prevent cognitive decline and oxidative damage
• Vitamin E & Vitamin C – Antioxidants which have a synergistic benefit in protecting mitochondria from age-associated oxidative damage and it has been shown that in cases of CCD, vitamin E levels in the brain are significantly reduced.
• α-Lipoic Acid – A powerful mitochondrial antioxidant capable of regenerating most other antioxidants. α-lipoic acid protects cortical neurons from β-amyloid and hydrogen peroxide induced cytotoxicity and reduces lipofuscin levels. Synergistic antioxidant effects have been demonstrated with vitamin E, Coenzyme Q₁₀ and Acetyl L-Carnitine. α-lipoic acid has been reported as toxic in cats and as such, is not included in AKTIVAIT® Cat.

In clinical trials, it was indicated that AKTIVAIT^® has a clear, beneficial effect on aspects of behaviour associated with CCD (Heath, Sarah 2007).

Given that cognitive dysfunction is a progressive and irreversible condition it it recommended to start supplementation when any tell-tale behaviour signs are identified and all differential diagnoses have been ruled out (Neilson JC 2001; Heath, Sarah 2007).

Mental and Behavioural Support

Providing mental stimulation and environmental enrichment for dogs with CCD can help to improve cognitive function (Milgram, NW 2004) and has been shown to enhance neurogenesis and decrease brain pathology (Hu YS 2010).

Dogs with CCD will be suffering from memory and learning impairments; it is important not to get angry with the dog as this can cause further anxiety. Instead help your dog to relearn commands, use large visual or audio cues to aid navigation and discrimination. Any training stimulation should be given in short bursts as dogs with CCD have a limited concentration span.

Mixing stimulation such as above with consistent, moderate exercise and play can help enhance the quality of life for the dog.

Combining behavioural and environmental with the administration of nutraceuticals such as AKTIVAIT^® can have a potentially valuable role in maximizing the benefits of therapy in terms of increased quality of life (Heath, Sarah 2007).

References

Bain MJ, Hart BL, Cliff KD, Ruehl WW (2001). Predicting behavioural changes associated with cognitive impairment in dogs. JAVMA; 218 (11) 1792- 1795

Chapman BL and Voith VL (1990). Behavioural problems in old dogs 26 cases (1984-1987) JAVMA; 196: 944- 946

Cummings BJ, Head E, Afagh AJ, Milgram NW, Cotman CW (1996). Beta amyloid accumulation correlates with cognitive dysfunction in the ages canine. Neurobiology of Learning and Memory; 66: 11- 23

Hart BL, Neilson JC, Ruehl WW. Behavioural Changes in Ageing Dogs: A demographic analysis. In: Mills DS, Heath SE, Harrington LJ (1997). Proceedings of the First International Conference on Veterinary Behavioural Medicine; 31- 33

Heath, S.E., Barabas, S. & Craze, P.G. (2007), Nutritional supplementation in cases of canine cognitive dysfunction—A clinical trial, Applied Animal Behaviour Science, vol. 105, no. 4, pp. 284-296.

Hill, A.S., Werner, J.A., Rogers, Q.R., O’Neill, S.L. & Christopher, M.M. (2004), Lipoic acid is 10 times more toxic in cats than reported in humans, dogs or rats, Journal of Animal Physiology and Animal Nutrition, vol. 88, no. 3-4, pp. 150-156.

Hu, Y.S., Xu, P., Pigino, G., Brady, S.T., Larson, J. & Lazarov, O. (2010), Complex environment experience rescues impaired neurogenesis, enhances synaptic plasticity, and attenuates neuropathology in familial Alzheimer’s disease-linked APPswe/PS1DeltaE9 mice, The FASEB journal : official publication of the Federation of American Societies for Experimental Biology, vol. 24, no. 6, pp. 1667-1681.

Landsberg, GM (2010) An overview of clinical aspects and signs of age related cognitive dysfunction. J Vet Behav 5(3): 153-4

Liu, J. (2008), The Effects and Mechanisms of Mitochondrial Nutrient α-Lipoic Acid on Improving Age-Associated Mitochondrial and Cognitive Dysfunction: An Overview, Neurochemical research, vol. 33, no. 1, pp. 194-203.

Kitani K, Kanai S, Ivy GO, Carillo MC (1998) Assessing the effects of deprenyl on longevity and antioxidant defences in different animal models. Ann NY Acad Sci; 854: 291- 306

Milgram, N.W., Head, E., Zicker, S.C., Ikeda-Douglas, C., Murphey, H., Muggenberg, B.A., Siwak, C.T., Tapp, P.D., Lowry, S.R. & Cotman, C.W. (2004), Long-term treatment with antioxidants and a program of behavioral enrichment reduces age-dependent impairment in discrimination and reversal learning in beagle dogs, Experimental gerontology, vol. 39, no. 5, pp. 753-765.

Montuschi P, Barnes P & Roberts LJ (2007) Insights into oxidative stress: the isoprostanes. Curr Med Chem 14: 703-717

Neilson JC, Hart BL, Cliff KD, Ruehl WW (2002). Prevalence of behavioural changes associated with age-related cognitive impairment in dogs. JAVMA; 218 (11): 1787- 1791

Osella, M.C., Re, G., Badino, P., Bergamasco, L. & Miolo, A. (2008), Phosphatidylserine (PS) as a potential nutraceutical for canine brain aging: A review, Journal of Veterinary Behavior: Clinical Applications and Research, vol. 3, no. 2, pp. 41-51.

Salvin, H.E., McGreevy, P.D., Sachdev, P.S. & Valenzuela, M.J. (2011), The canine cognitive dysfunction rating scale (CCDR): a data-driven and ecologically relevant assessment tool, Veterinary journal (London, England : 1997), vol. 188, no. 3, pp. 331-336.

Tapp PD, Siwak CT, Gao, FQ (2004). Frontal lobe volume , function and β-amyloid pathology in a canine model of aging. J Neuroscience; 24: 8205-8213

Wei, Y.H. (1998), Oxidative stress and mitochondrial DNA mutations in human aging, Proceedings of the Society for Experimental Biology and Medicine.Society for Experimental Biology and Medicine (New York, N.Y.), vol. 217, no. 1, pp. 53-63

There are a number of situations when animals can experience anxiety. For example, dogs can develop phobias towards loud noises such as fireworks. Other examples of causes of canine anxiety include:

• Separation (Separation anxiety)
• Travelling
• Kennelling and extended owner absence
• Veterinary or Groomer visits

When pets are subject to anxiety and stressful situations, it can be distressing for both the owner and the pet. As such, a number of treatments for relief of anxiety and/or phobias have been developed, particularly for dogs and cats.

Development of Anxiety and Phobias

Anxiety is a natural, emotional response to a potentially harmful stimulus (also known as a stressor). Fear inducing stimuli initiate two pathways within the brain, these pathways (discovered by Joseph LeDoux) are sometimes referred to as the ‘High Road’ and the ‘Low Road’.

Both pathways originate in the thalamus following exposure to a stressor, from there, the signal splits to follow two separate paths simultaneously – one taking the ‘low road’, the other taking the ‘high road’. Following the initial stimulus, a signal is generated in the thalamus and propagated directly to the amygdala – the primary processing unit for dealing with memories of emotional reactions. This results in the production of an immediate reaction to the stressor. A human comparison would be ‘jumping’ in response to a loud noise.

A signal is also simultaneously propagated along the ‘High Road’. The signal again, travels from the thalamus to the amygdala; however, it travels via the sensory cortex and the hippocampus. The result of this is the ability to associate the stressor with previous learned experiences, thus a more rational response to the stressor is produced (Neilson JC, 2002).

For example, a typical dog owner may regularly receive visitors to their home. As the dog is learning to interact with these visitors, they may feel threatened by the presence of someone new and show anxiety in the form of vocalisation i.e. barking. Over time however, the dog may learn to associate that the visitor is not a threat from previous experience and memories. Such behaviour would result from information being relayed to the amygdala via the ‘High Road’.

Output from the amygdala controls musculoskeletal responses and also activates the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is involved in the neurobiology of mood disorders, such as anxiety. This is because it controls (in response to a stressor) the release of the major stress hormone – cortisol (Le Doux 2000).

The amygdala also regulates the release of adrenaline, which promotes the sympathetic nervous system and noradrenaline another stress related hormone. Both adrenaline and noradrenaline are neurotransmitters.

Because the amygdala is able to generate a response to stressors based on memories, previous experiences and learnt responses, it ensures that in the majority of cases, an appropriate response is generated. Dysfunctional responses make up the basis of phobia development.

Anxieties and Phobias

Anxiety is a feeling of fear and apprehension. In dogs (as well as other animals and humans) anxieties can develop in to phobias. A phobia causes abnormal amounts of fear and stress in response to certain stimuli which typically are of a low threat level. Repeated exposure to a stressor which initiates a phobic response will not reduce stress levels upon further exposure, it may even exacerbate the phobia.

Because phobic responses put a large amount of stress of the individual, it is beneficial to attempt to ‘cure’ them. This is often achieved by pharmacological and/or behavioural management.

Below are a number of often-observed phobias and anxieties specifically seen in dogs.

Noise Phobias

One of the most common phobias exhibited by dogs is a phobia of noise. Typically, loud noises, such as fireworks, thunder or gunshot, can cause a dog to become excessively anxious. This anxiety is often expressed by trembling or vocalisation.

Almost half of dogs show an atypical anxiety response to loud noises – especially to fireworks. This anxiety is also more prevalent in older dogs and it is unlikely that they will spontaneously recover from such a phobia over time.

Due to the nature of this phobia, the best treatment would be one which is able to act quickly i.e. able to alleviate acute anxiety.

Separation Anxiety

By nature, dogs are social animals, this means many can become stressed or experience anxiety when they are left alone – for instance, when their owner leaves for work.

Prolonged and repeated separation anxiety can be caused by a number of factors including:

• A lack of prior habituation to an owner’s absence
• A change in the owner’s routine, resulting in different periods of absence
• Reinforcement of anxiety behaviour by giving lavish affection prior to departure and upon return

There are a number of tell-tale signs which show whether a dog is suffering from separation anxiety, these include:

• Causing damage and destruction to their environment (i.e. household furnishings) in your absence
• Become vocal before and shortly after you leave
• Soiling the household areas
• Causing self trauma such as ‘lick granulomas’ – inflammation due to excessive licking of an area

These actions can again be distressing for both the dog and the owner.

Situational Phobias

Situational phobias can arise for a number of reasons from varying environments and stimuli. Typically, such phobias develop due to a previous negative association with stimuli. They can also arise when a dog is exposed to a new situation or for seemingly no reason at all.

The clinical signs of a dog suffering from a situational phobia are the same, no matter what the trigger stimulus is. These signs can include any of the following; vocalisation, trembling, urination/defecation, attempted escape, reluctance to leave the owner’s side or in rare cases, aggression.

Some common examples of situational phobias include:

Travelling – Some dogs are quite happy to travel in a vehicle, some even enjoy it! However, there are a proportion of dogs that will experience varying levels of distress and anxiety from travelling.

Anxious dogs will be vocal and may be reluctant to remain still. They may also defecate or urinate whilst travelling and/or vomit.

It is possible that a vomiting dog is suffering from motion sickness and not anxiety; however, it is common for these conditions to co-exist. In fact, they often exacerbate one another. In such cases, the dog should initially be treated for anxiety and if the problem persists an anti-emetic such as CERENIA® should also be given.

Kennelling – Leaving a dog in kennels whilst away can be traumatic for a number of reasons. The dog is being introduced to a new, possibly hectic environment where contact with other dogs will be increased.

Daily routine will also be likely to alter; these factors combined with an absence of the owner can be distressing for the dog. Treating the dog pre-emptively for anxiety would obviously be beneficial.

Visits to a Groomer/Veterinarian – Dogs (and other animals) can quickly associate a visit to a vet (and in some cases, a Groomer) with a negative experience. As such, it is quite possible for phobias to develop. The associated clinical signs of anxiety will also develop, including aggression, vocalisation, defecation and urination.

Dogs are particularly prone to the development of aggression when visiting a vet or groomer due to the close contact nature of the respective professions with the animal. When aggression is shown, this can result in injuries towards the vet/groomer, the owner and even the dog itself.

Managing Anxiety and Phobias

A wide variety of treatments is currently used to control and limit anxiety and the development/progression of phobias. Such techniques include; training and behavioural programmes, the use of pheromones, dietary management, pharmaceutical use and nutraceutical use.

Training and Behavioural Programmes

A large proportion of anxiety disorders and phobias can be prevented by implementing correct training during the ’socialisation period’ of a puppy. The socialisation period, is the short length of time at the beginning of a puppy’s life when they are particularly receptive to stimuli, there are many thoughts on the actual length of this period but it generally agreed that it does not exceed the first 16 weeks. Correct introduction and exposure to stimuli and stressors during this period can help prevent the development of anxiety disorders or phobias during later life (Shepherd K, 2002). Of course, this isn’t always possible, for example, following the adoption of a previously ill-treated adult dog.

Reducing anxiety in older dogs through behavioural programmes is possible though. One technique is to follow a desensitisation programme. The best example of using a desensitisation programme to reduce anxiety is the use of recorded audio to treat noise phobias.

This type of programme would involve playing previously recorded audio of a known stressor (such as fireworks) repeatedly, building the volume slowly over time to enable the dog to become habituated to the sound. Desensitisation programmes are just used for dealing with noise phobias, the principle behind them can be applied to a number of situations to deal with anxiety and phobias. Another example of use would be using a desensitisation programme for the treatment of separation anxiety. This would involve mimicking signals typically associated with separation, such as picking up keys or putting on a coat. Over time, you would build this process up, possibly leaving the house for a couple of minutes then returning. If successful, this would eventually reduce the clinical signs of anxiety as the dog learns that separation need not be associated with a negative experience.

Another type of behavioural programme is ‘counter conditioning’; this is similar to classical conditioning (i.e. the process used to teach a dog tricks such as ‘sit’ or ‘stay’), but it attempts to replace the association of a stimulus with a negative experience, with a new, positive experience.

Extending the typical example of Pavlov’s dog allows for a simple explanation of counter conditioning. Imagine we make a dog learn to associate the ringing of a bell with a negative experience, such as a light electric shock (classic conditioning). Now, if we instead started giving food to the dog following the ringing of the bell, the dog would eventually learn to associate the bell with a new, positive experience. This is counter conditioning.

When care and time is invested in to training or behavioural programmes such as desensitisation or counter conditioning, they have been shown to decrease the fear response exhibited following exposure to a stressor, however each dog is different and will respond to the courses in their own time. This means the length of time to overcome anxiety by these means is often undeterminable.

Pheromones

Pheromones are volatile hormones, secreted outside of the body by a number of species.  Pheromones initiate specific social responses in other individuals of the same species, the number of responses which can be initiated vary widely.

A pheromone of particular interest in dogs, for the treatment of anxieties, is a synthetically manufactured ‘appeasing pheromone’ known as Dog Appeasing Pheromone or DAP.  DAP is a naturally occurring pheromone which was initially extracted from lactating bitches. DAP has been shown to support both puppies and adult dogs during stressful situations.

For therapeutic use in dogs, DAP is made airborne. This is achieved by using short range plug-in diffusers, sprays or heat activated collars. Once airborne, DAP reaches the vomeronasal organ of the dog which is located in close proximity to the oral cavity and the nasal passage. The role of the vomeronasal is to respond to chemical messengers i.e. pheromones and initiate the appropriate response. Each pheromone produces a single, specific response and can only achieve this response in conspecifics. DAP invokes a calm and reassured mood.

Due to the nature of how DAP works, the collars, diffusers and sprays must be sent up in advance of an expected stressful event (such as introduction in to a new home). CEVA, the animal health company behind DAP, market the product as Adaptil. They recommend attaching DAP-infused collars 24 hours before contact with an expected stressor (for example, a car journey). Also, because the collars are activated by heat, they must be attached with a tight fit which may prove uncomfortable for the dog. It is recommended, again by CEVA, that plug-in diffusers are installed around 2 weeks before exposure to the expected stimulus. Although it is claimed the diffuser is fully functional after 24 hours, they suggest waiting up to month before evaluating the diffuser’s effectiveness. DAP in spray form is faster acting, but has only a short, local area of effect.

Because of these limitations, pheromones, such as DAP, are not recommended for use in acute situations. The sole use of pheromones is not recommended for severe phobias, severe cases should incorporate pheromone use with other anxiolytics.

The use of pheromones is not without its doubts. Their efficacy has long been questioned, both in humans and animals. CEVA suggests that the efficacy of the Dog Appeasing Pheromone has been proven by a number of studies however, the Journal of American Veterinary Medical Association have published systematic reviews of pheromone associated clinical trials. In these reviews they suggest that the majority of the clinical trials provide insufficient evidence.

Dietary Management

A more traditional method of reducing anxiety is by carefully controlling the diet, prior to an expected stressful event. By closely following the below feeding regime, it is possible to elevate levels of serotonin (of which low levels predispose individuals to mood and impulse control disorders).

Start by feeding the dog a large, protein rich meal, supplemented with 1mg of vitamin B6 per 1kg of body weight. Vitamin B6 plays an important role in the synthesis of serotonin and the metabolism of tryptophan to serotonin.

After 2-3 hours, the dog should be fed a small, carbohydrate meal – only 2g per 1kg of body weight, this has been shown to stimulate the production of insulin.

Insulin release induces uptake of large branched chain amino acids (excluding tryptophan) in to the muscles. Typically there is competition between tryptophan and other branched chain amino acids (BCAAs) for access to transporters at the blood-brain barrier and as such, there is also competition for uptake in to the brain tissue.

Because tryptophan is a precursor of serotonin, the lack of competition between tryptophan and other BCAAs increases the levels of serotonin in the brain, provided there are fewer BCAAs at the transporter.

The problem with dietary management to control anxiety, is that it requires adhering to the above, strict regime. Also, for this regime to work optimally, the dog would be required to have high, initial levels of tryptophan which is dependent on the quality of the protein meal. A tryptophan containing supplement would be more ideal. One other factor to consider is that controlling the diet would not be suitable for acute situations as preparation is required at least 2 hours in advance.

Pharmaceuticals

The neurobiology of anxiety involves a number of neurotransmitters; primarily serotonin, dopamine, GABA and noradrenaline. To medicate for anxiety, any dysfunction or imbalances in these neurotransmitters must be addressed.

When exposed to a stressor, the activity of the involved neurotransmitter pathway is altered. The activity of the serotonergic and GABAnergic pathways are decreased whilst the activity of noradrenaline pathways are increased.

GABA is a major inhibitory neurotransmitter, with around 50% of inhibitory synapses being GABA mediated; these inhibitory synapses are prevalent at all levels of the CNS. In response to a stressor, the overall activity of GABA is decreased which results in a decrease in brain inhibition and thus reduces the likelihood of the brain achieving a calm state.

Treating anxiety and phobias with pharmaceuticals can be achieved with a variety of drugs, each with different pharmacodynamics.

Anxiolytic and Amnesic Drugs

Anxiolytics such as benzodiazepines are used to provide short term relief from anxiety. Benzodiazepines such as diazepam provide short term CNS sedation. For treatment of serve anxiety and phobias, long term use of benzodiazepines may be prescribed by a veterinarian; however, this can lead to dependence and the development of withdrawal symptoms.

A popular benzodiazepine used in the treatment of canine anxiety is alprazolam (Xanax). Alprazolam is an anxiolytic which yields short term CNS sedation as well as anterograde amnesic effects. Anterograde amnesia is also known as short term memory loss i.e. an inability to recall the recent past. The benefit of being able to induce anterograde amnesia alongside general anxiolytic effects is that you are able to administer the drug either before or after a stressful event. The anterograde effect of drugs such as alprazolam make it difficult for the dog recall the event, reducing anxiety and helping to prevent the development of phobias.

Alprazolam and similar drugs cause anxiolysis by acting as an agonist of the GABA receptor i.e. the drug mimics the structure of the GABA neurotransmitter and binds with efficacy to increase the action of inhibitory synapses. The short term memory loss induced by amnesic drugs is due to antagonism of NDMA receptors i.e. the drug binds without efficacy but with great affinity, essentially blocking the receptor.

Adverse effects of amnesic and anxiolytic drugs include; ataxia, paradoxical hyperexcitability, and disinhibition. Disinhibition is of concern as it increases the likelihood of aggression.

Sedative Drugs

Sedative drugs such as acepromazine (ACP) cause sedation, but do not produce any anxiolytic effects. This means that a dog treated with a sedative drug would be immobilised and appear calm, yet in reality they are still aware of their environment and current situation. As such they can still form emotional responses to a stressor.

Because of the nature of such drugs, the intensity of the emotional impact from a stressor may actually increase, as the dog is aware of the situation but unable to react in a manner to reduce its anxiety.  This will negatively impact on any previous existing anxieties or phobias, possibly undoing previous corrective action and creating negative associations for future interactions with the stimulus.

The reliability of sedative drugs when administered orally is unreliable and, as such, high doses of the drug may be required. Using high doses however, can cause systemic effects such as hypervolemia (increased blood-fluid volume), hyperexcitability and extrapyrimidal side effects such as akinesia (an inability to move) or akathisia (an inability to remain still).

Because of all the associated problems with sedative drug use, they are no longer recommended for use in treatment of phobias or anxiety (Neilson JC, 2002; Casey R, 2002).

Antidepressants

Tricyclic Antidepressants (TCAs) & Selective Serotonin Re-uptake Inhibitors (SSRIs) – These two variants of antidepressants both work in a similar manner, the increase the amount of available serotonin in the synaptic cleft. This is achieved by blocking re-uptake of serotonin after its release; this makes stimulation of post synaptic responses possible which includes some secondary messenger systems.

Enhancing secondary messenger systems in this way is beneficial as the systems involved contribute towards cell memory which plays an important role during training programmes such as counter conditioning.

There are a number of side effects associated with these drugs including; unwanted sedation, constipation, diarrhoea, urinary retention, appetite changes, ataxia, cardiac arrhythmia and alterations in blood pressure.

Monoamine Oxidase Inhibitors (MAOIs) – MAOIs, specifically monoamine oxidase B inhibitors, inhibit the MAO enzyme responsible for the breakdown of MAO neurotransmitters. Presently, few studies support the use of MAOIs for phobias; however there is one licensed veterinary preparation available for purchase (Selgian) which has been used to treat sound and noise related phobias.

CEVA, the producers of Selgian, state that it can take anywhere from 4 to 8 weeks before the clinical signs of anxiety associated with noise related phobias are reduced.

Also worth noting is that MAOIs are contraindicated with many other drugs, including TCAs and SSRIs and therefore they should not be administered together as drug-induced CNS toxicity can develop. Other side effects of MAOIs include; possible aggression, excess salivation, vomiting and serotonin sickness (caused by a large excess of serotonin).

Beta Blockers

Beta blockers, such as propranolol, are best used to treat cases of mild anxiety which is indicated by trembling, tachycardia (increased heart rate) and tachyponea (increased ventilation rate).Beta blockers are typically used pre-emptively to modulate the body’s response to neurochemical signals initiated by exposure to a stressor.

It is also possible to use beta blockers to amend the long-term potentiation of a phobic response, but this requires early action. Cases are typically not presented early enough to follow this course of action however.

The use of beta blockers with SSRIs and TCAs is considered safe.

Nutraceuticals

Nutraceuticals are available for the treatment of a variety conditions and due to their natural sources, efficacy and lack of side effects they are widely praised. In terms of treating anxiety and phobias in dogs, there are currently two main products, these are Zylkéne and CALMEX®.

Zylkéne

Zylkéne is a natural product derived from cow’s milk, it has been clinically proven to “help cats and dogs manage stress and facilitate adaption to change.”

The active ingredient of Zylkéne is alpha-casozepine, a decapeptide which is isolated from bovine tryptic-casein. It is worth noting that Zylkéne relies solely on this single active ingredient.

In clinical trials, Zylkéne has only been tested for its long term effects (tested over a period of 56 days). A reduction in anxiety related clinical signs following the use of Zylkéne were only observed after a couple of weeks. The use of casein tryptic hydrolysate i.e. Zylkéne has not been recommended as an alternative to benzodiazepine for acute treatment of anxiety (recommendation made by Jamie Rushton, a clinical Behaviourist and Veterinarian), despite often being referred to as ‘the natural benzodiazepine’.

The actual method in which Zylkéne is able to manage anxiety is currently unknown. It is believed it may be due to the affinity of alpha-casozepine for GABA receptors due to its structural similarities to the GABA neurotransmitter.

CALMEX^®

Another nutraceutical product is CALMEX^®, a unique combination of two amino acids, a psychoactive plant extract and numerous B Vitamins. These ingredients produce a synergistic effect by modulating neurotransmitter production and multiple other pathways within the brain. The result is acute anxiolysis and mild sedation. CALMEX^® can be used alone or in conjunction with behavioural programmes.

CALMEX^® includes the essential amino acids L-theanine and L-tryptophan. L-theanine (found in green tea), is both fast acting and safe, with a GRAS approval by the FDA.

L-theanine

L-theanine is able to cross the blood brain barrier within 30 minutes of ingestion (Bryan J, 2008); upon crossing the blood brain barrier L-theanine almost instantly begins inducing the production of alpha waves by the brain. Alpha waves are associated with the relaxed state of mind.

Other functions of L-theanine include:

• Increasing GABA neurotransmitter production, the main neurotransmitter associated with inhibition and a relaxed state
• Decreasing noradrenaline production, an excitatory neurotransmitter which is normally present in elevated levels during periods of anxiety
• Increasing the concentration of serotonin in the stratum, hippocampus, and hypothalamus. Serotonin is proven to alleviate anxiety

Clinical trials have shown that L-theanine is effective in reducing fearful behaviour and its use for treating anxiety related behaviour is supported (Araujo et al, 2010). It has been shown to have a regulatory role within the CNS which can modulate and tone down CNS response.

L-tryptophan

L-tryptophan is a precursor of serotonin, an important hormone and neurotransmitter involved in regulating mood, behaviour and cognition. L-tryptophan has also been shown to decrease aggression in dogs (De Napoli et al, 2000), as well as decrease stereotypies and stress responses (Pereira et al, 2010).

Because L-tryptophan, like L-theanine, is an essential amino acid, dietary depletion results in reduced plasma concentration. This consequently leads to a reduction in the synthesis and release of serotonin in the brain (Bell C et al, 2001).

Piper Methysticum  

CALMEX^® also includes a psychoactive plant extract, Piper methysticum, which, when taken orally, has been used for thousands of years for the treatment of anxiety, stress and insomnia. P.methysticum, or Kava as it is commonly known, can also be applied topically to produce analgesic and wound healing effects.

The clinical effects produced by P. methysticum are similar to benzodiazepines. It has anxiolytic, sedative and anticonvulsant properties and is also used as a muscle relaxant (Jussofie at al. 1994).

In terms of safety P. methysticum has been clinically proven to be both a safe and effective treatment for anxiety, with strong evidence to support its anxiolytic effects (Sarris, 2011; Lakhan S.E., 2010).

The anxiolytic effects of P. methysticum are achieved by:

• Modulation of GABA activity by altering the lipid membrane structure – interfering with voltage-gated ion channels (Sarris, 2011)
• Producing reversible MAO-B inhibition and is increasing dopamine levels in the brain
• Inhibiting dopamine and noradrenaline re-uptake

The sale of P. methysticum for oral use in humans was prohibited in the UK in 2003 based on theories that there may be an associated risk between hepatotoxicity and Piper methysticum.

Some experts, however, argue that causality between the adverse effect and use of P. methysticum has not been established with sufficient certainty. In several cases, liver damage could have been due to other drugs or alcohol taken concomitantly. In other instances, excessive and prolonged doses of P. methysticum had been used (Ernst E, 2007).

In terms of veterinary use, P. methysticum has been listed on the European Feed Additive list since 2005 and remains on the list to date after being reviewed again in 2010.

B Vitamins 

A number of B vitamins responsible for essential maintenance of the nervous system are included within CALMEX^®. These include vitamins; B1, B3, B6, B8 and B12.

It has been proven that these vitamins support the availability and production of key neurotransmitters such as; serotonin, noradrenaline, GABA and dopamine (Combs GF, 2008). Vitamin B6 is also important in the synthesis of coenzyme pyridoxal phosphate which is essential in metabolism of serotonin.

Synergistic Properties of CALMEX^®

CALMEX^® ingredients utilise multiple pathways of the brain involved with mood regulation to achieve a synergistic result. Only pure, natural ethically sourced products are used which have been proven to be effective. The synergistic action of these ingredients produces anxiolysis and mild sedation making CALMEX^® a perfect choice for dealing with anxiety and phobias.

Because the active ingredients of CALMEX^® work rapidly, it can be used for acute situations without requiring prior preparation, perfect for unexpected situations.

Conclusion

A phobia can quickly develop in dogs and there are many occasions where anxiety arises. These situations can be stressful for both the dog and owner. Dogs can be put under immense emotional stress which can affect their state of mind, just as it would with a human, which is why owners should seek advice or help if they notice the clinical signs of anxiety.

From the techniques and treatments listed earlier, you can see that each have their own pros and cons, those treatments again in summary:

• Training and behavioural programs – No use of products required however varied results and the programmes can last a long time which requires a lot of commitment from the owner
• Pheromones – Controversy still surrounds their actual efficacy, DAP does show some promise however its use requires prior preparation meaning it is not suitable for acute development of anxiety such as that experienced with sudden fireworks.
• Dietary Management – Not suitable for acute development of anxiety and the anxiolytic effects are limited. Much more beneficial to use a tryptophan supplement.
• Pharmaceuticals – Can have good anxiolytic effects (and in some cases amnesic). The optimal pharmaceutical for anxiety treatment would be benzodiazepines however; it can produce a number of side effects including paradoxical hyperactivity.
• Nutraceuticals – Natural ingredients and good efficacy.

References

Araujo et al. 2010. Anxitane tablets reduce fear of human beings in a model of anxiety-related behaviour. Journal of Veterinary Behavior 5, 268-275

Bell C, Abrams J, Nutt D, 2001. Tryptophan depletion and its implications for psychiatry. Br J Psyschiatry. 2001 May; 178:399- 405

Bryan J. 2008. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutr Rev. 2008 Feb;66(2):82-90.

Casey R, 2002. BSAVA Manual of Canine and Feline Behavioural Medicine. Chpt 15. Edited by D. Horwitz, D. Mills and S. Heath

Combs, G.F. 2008. The Vitamins: Fundamental Aspects in Nutrition and Health. San Diego: Elsevier

De Napoli et al. 2000. Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs. Journal of the American Veterinary Medical Association Vol. 217, No. 4, Pages 504-508

Ernst, E. 2007, “A re-evaluation of kava (Piper methysticum)”, British journal of clinical pharmacology, vol. 64, no. 4, pp. 415-417.

Lakhan SE, Vieira KF 2010. Nutritional and herbal supplements for anxiety and anxiety-related disorders: systematic review. Nutr J. 2010 Oct 7;9:42

Jussofie at al. 1994. Kavapyrone enriched extract from Piper methysticum as modulator of the GABA binding site in different regions of rat brain. Psychopharmacology (Berl). 1994 Dec;116(4):469-74.

Le Doux 2000. Annual Review Neuroscience 23:155–184. Emotion Circuits in the Brain.

Le Doux et al 1988. The Journal of Neuroscience. 8(7): 2517- 2529; Different projections of the central amygdaloid nucleus mediate autonomic and behavioral correlates of conditioned fear

Neilson JC, 2002. BSAVA Manual of Canine and Feline Behavioural Medicine. Chpt 18. Edited by D. Horwitz, D. Mills and S. Heath

Pereira et al. 2010. Effect of dietary intake of L-Tryptophan supplementation on working dogs demonstrating stress related behaviours. BSAVA congress 2010 Scientific Proceedings.

Sarris 2011 Kava: a comprehensive review of efficacy, safety, and psychopharmacology. Australian and New Zealand Journal of Psychiatry 2011; 45:27–35

Schmidt, M., Nahrstedt, A. & Lüpke, N.P. 2002, “Piper methysticum (Kava) in der Diskussion: Betrachtungen zu Qualität, Wirksamkeit und Unbedenklichkeit***”, Wiener Medizinische Wochenschrift, vol. 152, no. 15-16, pp. 382-388.

Stevinson, C., Huntley, A. & Ernst, E. 2002, “A systematic review of the safety of kava extract in the treatment of anxiety”, Drug safety : an international journal of medical toxicology and drug experience, vol. 25, no. 4, pp. 251-261.

Young, S.N. & Leyton, M. 2002, “The role of serotonin in human mood and social interaction. Insight from altered tryptophan levels”, Pharmacology, biochemistry, and behavior, vol. 71, no. 4, pp. 857