What are allergies?
Allergies occur when an individual is exposed to a substance known as an “allergen,” which causes the body’s immune system to overreact. Many symptoms can arise, including GI upset and extreme itchiness, resulting in self mutilation and secondary infections.
Unfortunately, there is no cure for allergies. Typically, the goal is to control symptoms and thus improve the quality of life for your pet.
- Food Allergy
- Food allergies are typically caused by a sensitization to glycoproteins found in food. There is no known inheritance associated with the illness, and signs generally appear around one year of age. It is estimated that there is a higher prevalence of food allergies in animals compared to humans, possibly due to an increased rate of gastrointestinal parasitism and viral enteritis. These issues damage the intestinal tract, thereby allowing the allergens to bypass normal immune barriers more readily. Clinical symptoms may include itching, licking, GI upset such as vomiting, diarrhea, belching, and frequent bowel movements, and chewing of the paws, ears, flank, groin and neck. These signs are often evident year-round, unlike seasonal allergies.
Diagnosis generally depends on hypoallergenic food trials. A thorough history, including documentation of all food, scraps and treats is important. Next, a diet containing a novel protein (meaning the dog has never consumed it before) is selected as a new food for the animal. Commercial diets sold in pet stores are not recommended as claims such as “hypoallergenic” have no meaning and are often misleading. Instead, options such as prescription diets, low antigen diets and homemade diets are more effective. Prescription diets are formulated to always contain the same novel protein and carbohydrate ingredients, and are available through your veterinarian. Similarly, antigens are the portions of proteins that trigger an immune response. Therefore, low antigen diets contain formulated (hydrolyzed) proteins, which contain antigens so small that they are unable to stimulate an allergic reaction. Lastly, homemade diets can be used when concurrent medical conditions precludes the use of any diets listed above. This is typically a last resort, as it is more time consuming and more difficult to balance the nutrients. Whichever route is chosen, the trial should continue for a minimum of 6-8 weeks, with no unapproved food such as table scraps and treats being given during this time.
The prognosis for food allergies is good provided that you are able to identify and avoid the offending ingredient. If not, there are medications available that can assist with treatment. If the food trial resolves the symptoms, the pet can remain on the hypoallergenic diet indefinitely, revert back to the original diet to ensure the symptoms were indeed a result of that diet, or add individual ingredients from the original diet in small amounts to the hypoallergenic diet to identify the exact allergen. The latter test is known as “provocative exposure testing,” and while allergens typically cause reactions within 2-3 days, it can take up to 2 weeks. Therefore, each ingredient should be added at 2 week intervals. Many owners may opt to remain on the hypoallergenic diet, as the second two options may result in a recurrence of symptoms that they do not want to deal with.
- Flea Allergy Dermatitis
- Flea Allergy Dermatitis is caused by a reaction to flea saliva. If your pet is sensitive to these parasites, it is imperative to control any infestations by routinely checking your pet and utilizing prophylactic medications.
- Atopic Dermatitis (Atopy)
- Airborne allergens such as pollen, dander, grasses, trees, and fabrics commonly cause allergies in both people and pets. This can lead to atopic dermatitis, which is irritation and itchiness on various parts of the body. In dogs, this occurs especially around the eyes, mouth, armpits, abdomen, legs, around the anus and within the ears (often leading to ear infections). Conversely, cats tend to have rashes and hair loss around their face and other various parts of the body. This problem typically begins as a seasonal itchiness and may eventually span the entire year. As with food allergies, atopic dermatitis tends to present early in life.
Similar to humans, skin testing can be performed to potentially identify the offending agent. As well, a number of treatments are available, including steroids (such as prednisone), antihistamines, fatty acid supplements, cyclosporine (for dogs), topicals, hyposensitization (allergy shots), or a combination of these. It should be noted that each animal will respond uniquely to different treatment regimes, with prednisone typically acting as the first line of defense and providing the most reliable and consistent results. However, given that prednisone is a hormone, it therefore has the potential to affect many body systems. As a result, it may not be appropriate in a number of circumstances, thereby necessitating alternative treatments.
- Vaccination Allergy
- During your pet’s annual veterinary visit, they are generally given a number of vaccinations to prevent them from contracting certain diseases. While a degree of pain at the injection site, lethargy and even fever can be normal, some dogs may have allergic reactions to these shots. If your pet experiences symptoms more severe then those listed above, contact the veterinarian immediately so that anti-inflammatory medications can be administered to halt the potentially lethal cascade of events. If your pet has ever experienced an event like this, it is important to ensure that the veterinarian is aware so that preventative measures can be taken. This may include administering vaccines independent of one another, or post-vaccination monitoring at the clinic.
If you wish to avoid allergies, it helps to pick the correct parents. The more ancestors with allergies, the more likely you are to have allergies. For our pets, when picking a pet try to find out the allergy history of the previous 2 or 3 generations. If there is history of allergies in the those, you may wish to consider a different breeder or litter.
Allergic pets should be vaccinated while there is snow on the ground. This reduces the risk of an immune system mis-targeting an allergen while processing the information in a vaccine.
Fleas should be controlled vigorously in households with allergic pets as the bite of the flea is the most potent trigger of the allergy system.
Higher quality diets have higher levels of the essential fatty acids that raise the allergen exposure threshold so the body has to be exposed to more of what it is allergic to before allergy symptoms will appear. From that basic diet level there are diets formulated to specifically help with allergy symptoms and then even more specialized diets to help treat food allergies as well. Supplementing with essential fatty acids is only advisable if the diet is of low quality (but better to buy a better food). Once into the better diets, adding more can unbalance the fatty acid ratios and defeat the purpose of the diet.
There is no evidence that any particular ingredient in the diet causes allergies. If an allergy exists to a particular ingredient, it is wise to avoid it. For individuals showing tendencies to allergies, it is wise to limit the exposure to as small a number of ingredients as possible. If they develop a true allergy later in life there are then alternative ingredients to turn to.
There is a link between internal parasites(worms) and allergies. Good parasite control from birth is currently recommended to help reduce the risk of allergies.