The low-down on pet allergies

miniature pinscher scratchingThese days it’s not uncommon to hear of pets with allergies so we asked Dr. Wendy James, BSc,  DVM, owner of Calgary Pet Wellness and Spay/Neuter Clinic and an associate at SouthPointe Pet Hospital, to give us the low-down on pet allergies. Dr. James is currently enrolled in Royal College of Veterinary Surgeons Certificate of Advanced Veterinary Practice in Dermatology.

Q: What are most pet allergy symptoms caused by — something in the environment or food?

A: Environmental allergies are more common than food allergies but certain breeds may be more predisposed to food allergies. It is estimated that 10 to 15 per cent of dogs with allergy symptoms have food allergies. In some cases both food and environmental allergies can be causing the pet’s symptoms.

Q: What are the typical symptoms of allergies?

A: The symptoms of allergies in dogs and cats are highly variable but can include one or all of the following: licking, chewing, scratching, scooting, recurrent ear infections, hair loss, recurrent skin infections, conjunctivitis, feline asthma and gastrointestinal problems.

Q: How are allergies diagnosed?

A: There is no test to diagnose environmental allergies. It is a diagnosis of exclusion which means all other causes must first be ruled out. Tests may need to be done for bacterial/fungal infections, parasites and food trials to rule out food allergies. Tests such as skin scrapings, cytology, fungal cultures, blood work and skin biopsies may need to be performed. If the pet is still showing symptoms after all of the other causes have been ruled out or treated then a diagnosis of environmental allergies can be made.

A blood or intradermal (skin prick) test is done not to diagnose the allergy but to determine what items need to be included in the allergy serum. There is no accurate test in animals to diagnose food allergies. Blood tests, skin tests or tests on hair samples have been shown, through research studies, not to be accurate when compared to what items the animals have a visible reaction to.  The only way to determine if your pet has food allergies is with a strict food trial. This involves giving a completely new protein source that the pet has never consumed for a minimum of eight weeks with no other food items, treats or supplements. The diet selected for the food trial is very important and should be discussed with your veterinarian. A food allergy can be diagnosed if the symptoms improve on the trial diet then relapse when the original food is reintroduced.

Q: What can you do to help if your pet is suffering from environmental allergies?

A: The best method of control of environmental allergies is immunotherapy or allergy vaccinations. This involves giving the pet a small amount of the allergens which increases over time to “retrain” the immune system and reduce the reaction. Immunotherapy is a very successful way to control environmental allergies and has no long term side effects. Most pets are maintained on one injection every two to three weeks. Prescription medications may be needed for short term relief from the symptoms to make the pet more comfortable while the diagnosis is being made. Shampoo therapy, topical products and essential fatty acid supplements can also be used to help improve the skin barrier.

Q: What kinds of things can you do inside and outside your home to try to prevent environmental allergies?

A: Environmental allergies (also called atopy) are caused by a genetic abnormality in a component of the skin barrier as well as an abnormality in the way the immune system reacts to environmental allergens. This abnormal hypersensitivity reaction results in the production of substances in the body that lead to itching. Dogs and cats with atopic dermatitis will have reactions to many environmental allergens that enter the body by contact with the skin or inhalation.

Frequently cleaning in the house and the removal of grass, weeds and trees from the yard will help reduce the amount of exposure but will not prevent the symptoms. Nothing can be done to prevent or cure allergies but there are many things that can be done to control the symptoms. Dogs that have allergies should not be used for breeding as there is a genetic component.

Q: What’s the difference between a food allergy and a food sensitivity? How can you tell the difference?

A: The difference between a food allergy and sensitivity (or intolerance) is a true allergy has an underlying immune component and an intolerance does not. In both cases your veterinarian would choose an appropriate diet for the food trial. If the symptoms improve, a diet challenge with the original diet would be done 12 or more weeks later. If the symptoms were being caused by a food allergy then they would return when the old diet was introduced.

Q: What are some common food allergens?

A: There is not one food that is more likely to cause an allergy or one protein that is considered “hypoallergenic.” Every pet is different and some pets can have reactions to more than one food item. Any protein molecule can cause a reaction. A grain-free diet does not mean it is allergy free!

Allergies require life-long maintenance and can be very frustrating to manage. A step wise process is important when trying to make the diagnosis and rule out other causes.