Did you know that our beloved pets can have allergies like us? Dogs and cats, as well as our other domesticated species, can have allergies to environmental substances, pests such as fleas, and even ingredients in their food! Allergies to allergens can cause clinical signs such as licking and biting at paws, limbs, abdomen, and at the tail base, scratching at the ears, neck, or lips, brown salivary staining of the paws and around the mouth, hair loss or skin lesions, and gastrointestinal symptoms such as vomiting, diarrhea, inappetence, drooling, lip licking, or even weight loss. We tend to think of extreme itchiness and a positive pinnal pedal response (hindlimb kicking when the ears are rubbed) as being very suspicious for scabies (a type of communicable microscopic skin parasite), while skin lesions and itchiness around the low back and tail base are thought of as being very suspicious for flea allergies. Licking of the paws and skin lesions and/or hair loss around the anus can be seen with environmental and food allergies. Patterns of itchiness and skin lesions can be a helpful starting place in dogs, but are less helpful in cats. Patterns can provide helpful clues, but are not the end all be all of allergy diagnostics.
We see a lot of skin lesions on our patients as we are preparing them for ultrasound that make us wonder about the possibility of allergies.
It can be a challenge to decipher whether allergies are to blame for a patient's symptoms and if they are food or environmentally related. Fortunately you have us and your veterinarian!
Environmental allergies can involve indoor and outdoor allergens such as pollens, yeast/fungi/molds, bacteria, fleas, dust mites, food storage mites, cotton linters, animal dander, etc. Environmental allergies can be seasonal in the case of pollenating outdoor plants, they can be year-round with seasonal variation, or they can be year-round in the case of storage mites. Environmental allergens can result in itchiness, traumatic skin lesions, and secondary skin infections. Environmental allergens do not tend to cause gastrointestinal symptoms.
Food allergies on the other hand, tend to be year-round. They certainly can wax and wane due to exposure to the allergen, and they can cause itchiness, traumatic skin lesions, secondary skin infections, and gastrointestinal symptoms. Most food allergies are due to dietary hypersensitivity to proteins. The most common allergens are turkey, chicken, lamb, and beef which tend to be the most common proteins in dog food and chicken, turkey, and tuna which tend to be the most common proteins in cat food. Soy is a less common allergen in pet food, but it is becoming more common. It is much more rare for an allergen to develop to a carbohydrate or an additive, but it can happen. Gluten intolerances are exceedingly rare in pets, but can happen in some breeds such as Irish Setters, some of which have an inherited gluten sensitivity.
Environmental allergies can be pin-pointed via skin and serum allergy tests. When it comes to food allergies, commercial food allergy tests are inaccurate. Dietary trials, although more time consuming and cumbersome, are the gold standard for accurate diagnosis and treatment.
The management of allergic disease can involve a number of tools. For food allergies, identifying and avoiding the allergen is the best management tool. In the case of an unknown food allergen, avoiding all previously provided proteins, is a good start, as sensitization to an allergen requires previous exposure. Novel protein or hydrolyzed protein diet trials are the mainstay of treatment. A novel protein is a protein that the patient has not had previous exposure to, and a hydrolyzed protein, is a protein that has been broken up into small or individual amino acids (protein building blocks) that are thought to be too small to trigger an allergic reaction. Prescription novel or hydrolyzed diets are generally recommended by veterinarians because they are produced in such a way to prevent cross-contamination, they are balanced and complete, and they have research behind them. Seeing an improvement in or resolution of the clinical signs during the 8-12 week feeding trial is a positive result. Confirmation of a food allergy requires re-feeding the allergen and seeing if the symptoms return, however, most clients are not inclined to do that, understandably so.
For environmental allergies, avoidance would be ideal, but that is often impossible. Immunotherapy or allergy vaccines are often employed to slowly desensitize the patient to the allergen by exposing them to small amounts of what they are allergic to to almost retrain the immune system. This can result in tolerance to the allergen. Fortunately, there is usually a very low incidence of side effects including severe allergic reactions such as anaphylaxis. Other options include suppressing the immune system with immunomodulatory
drugs such as steroids or cyclosporine, providing anti-itch therapies such as cytopoint or apoquel (which also has anti-inflammatory properties), removing the allergens from the skin and from the environment with frequent bathing or the use of pet-safe wipes, and keeping bedding and food as allergen-free as possible, and treating secondary infections.
If you think that your pet may have allergies, please discuss it with your primary veterinarian. Board certified veterinary dermatologists are also available to assist with the diagnosis and management of allergic conditions as well as other skin conditions.
A special thanks to Dr. Stacey Holz, a board certified dermatologist that practices in the Bay Area, for reviewing this blog for correctness and completeness.
Also, thank you Dr. Holz for caring for my allergic pets! Learn more about Dr. Holz at: https://www.ggvets.com/about-golden-gate-veterinary-bay-area/
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