Allergies in Cats

Laurie Anne Walden, DVM

Photo by noelle on Unsplash

In cats, unlike humans, allergies don’t typically cause sneezing and runny eyes. Cats with allergies are more likely to have itching and skin disease. Some allergies in cats cause asthma and digestive tract disorders.
 
The most common allergies in cats are flea allergy, allergies to substances in the environment, and food allergies. Some cats have more than one kind of allergy.
 
Flea Allergy
For cats with flea allergy, even a few flea bites cause significant itching and skin disease. Signs include hair loss, broken hairs, scratches on the skin, scabs, or raised pink or red bumps.
 
Fleas are hard to find on cats because cats remove them when they groom, so you might not actually see any fleas on a cat whose skin disease is caused by a flea allergy. The pattern of hair loss is one clue to the diagnosis; hair loss on the lower back is usually related to fleas.
 
Because flea-related dermatitis is so common, flea treatment is standard care for cats with skin disease. Unlike many allergy triggers, fleas can be eliminated from a cat’s environment.
 
The best type of flea prevention to use depends on the individual cat, the cat’s lifestyle and environment, and contact animals. Your veterinarian can recommend products for your own cat. It’s easier to prevent a flea infestation than to eliminate one. In general, the most reliable way to avoid flea problems is to give effective (this often means prescription) flea prevention all year round to all cats and dogs in the household.
 
Environmental Allergies
The same substances in the environment that cause allergies in people also cause allergies in cats. Some allergy triggers (like grasses and trees) are seasonal; others (like dust mites and mold spores) are present year round. In cats, environmental allergies most often cause skin problems but are also linked to asthma.
 
Environmental allergies cause the same signs of skin disease as flea allergy. Allergies can also cause eosinophilic dermatitis, a type of inflammatory skin disease with red, scabbed, or oozy patches on the haired skin or the edges of the lips.
 
Asthma is fairly common in cats. Asthma flares can be seasonal in cats with environmental allergies. Signs include coughing, wheezing, and open-mouth breathing or panting; emergency signs are difficulty breathing and purple or blue gums.
 
Environmental allergy triggers typically can’t be eliminated. Cats with these allergies receive symptom relief (anti-itch medication) and treatment for the skin infections that are very common in animals with allergic skin disease. Cats with asthma need steroids, often delivered by inhaler. Immunotherapy (“allergy shots”) from a veterinary dermatologist can be used to treat environmental allergies if the exact triggers can be identified with a skin test.
 
Food Allergies
Allergies to food ingredients most often cause digestive tract problems like vomiting and diarrhea. In cats, food allergies can also cause skin disease. Vomiting and diarrhea have many possible causes, some of which are very serious, so cats with chronic (long-term) digestive tract symptoms need a full medical work-up.
 
Food allergies can be triggered by a wide variety of proteins and carbohydrates. Simply switching the brand or flavor of cat food—or switching to a homemade diet—won’t tell you if a cat has a food allergy. The only way to diagnose a food allergy is with a diet trial, which means feeding only an elimination diet (a prescription diet formulated to eliminate possible allergy triggers) for several weeks. For cats with food allergy, symptoms greatly improve if the problem ingredient is identified and eliminated.
 
Image source: https://unsplash.com/photos/orange-tabby-cat-on-gray-concrete-floor-bTw1Ug-Wlio

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