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Atopy in Cats

Atopy in Cats

General facts

  • Atopy is caused by an abnormal skin barrier, cat genetics and environmental factors.
  • It is defined by allergy symptoms resulting from repeated exposure to environmental substances such as pollen, mould, dust, etc.
  • Given the hereditary nature of this disease, certain breeds are more frequently affected, including Siamese.
  • Symptoms may be seasonal (April-May to October-November) or present throughout the year.


Clinical signs

In cats, the first allergy symptoms are itching. These occur mainly on the face, legs, abdomen, and ears. Cats who experience itching will scratch, lick and chew themselves in order to relieve these unpleasant sensations. Subsequently, lesions resulting from the itching may appear such as hair loss, redness, dandruff, papules, pustules, hyperpigmentation (blackening of the skin), etc. In many cases, bacterial or yeast superinfection contributes to the symptoms of inflamed and itchy skin. These cats are also prone to developing recurrent ear infections.

In the case of food allergies in particular, some digestive signs may also be present in addition to cutaneous signs, such as flatulence, diarrhea, rumbling, etc.



It is not easy! The veterinarian should first take your cat’s history and perform a complete physical examination. Subsequently, it is possible to take various samples from the skin which can be sent to the laboratory or taken to the clinic using a microscope.

Similar symptoms to atopy can be found in other skin diseases, such as flea bite allergy, food allergy, contact allergy, sarcoptic mange, folliculitis, etc. Therefore, the collection of information, the physical examination and the various analyses performed on your cat are crucial in order to establish the correct diagnosis and to proceed adequately to the treatment of the condition.


In the case of food allergies, the most reliable method of diagnosing or ruling out the condition is the elimination diet (hypoallergenic diet). It will be crucial to only serve the chosen hypoallergenic food for a period of 8 to 10 weeks, and not to give any treats (biscuits or strips) or table food during the entire trial period. The homemade elimination diet is the top recommendation if you are ready to cook for your cat, but commercial diets are also available. Several formulas are available in veterinary clinics. As an owner, it is sometimes difficult to find yourself faced with all the hypoallergenic food options available on the market. If you decide to choose this option, your veterinarian will be able to make the best recommendation for your cat's needs. The manufacturers of these diets guarantee that there is no contamination of potential allergens between each production. The best time of year to perform an elimination diet is during the winter, because there are no environmental allergens such as pollens and others that can skew the results.

In the case of atopy, when the homemade hypoallergenic diet or the commercial diet has been tried and your cat still shows symptoms of pruritus, the atopy diagnosis is more likely. Thus, the next step for confirming and identifying the different allergens causing pruritus is an intradermal allergy test. It’s also possible to use a serological test to diagnose the condition, but it is only very little used because it is less reliable than the intradermal allergy test.

Unfortunately, some cats can be affected by both food allergies and atopy, which can complicate the diagnosis.



Unfortunately, cats with allergies cannot heal from this condition. However, in most cases, the symptoms can be sufficiently controlled to allow optimal comfort.

In the case of food allergies, when a suitable diet can be found without allergens that your cat reacts to, the pruritus symptoms tend to resolve. On the other hand, your cat may be allergic to several food allergens and several diets may need to be tried before targeting the one that will suit him best. It is very important not to get discouraged in this whole process, which can become quite tedious!

Treatment of atopy:

An intradermal allergy test may be performed by a dermatologist in an effort to plan an immunotherapy vaccine that will desensitize your cat to targeted allergens. Normally, this test will be carried out from 3 years of age, to allow your animal to develop all its allergies. The hyposensitization vaccine is effective in about 75% of cases and takes between 3 and 12 months before the signs of pruritus subside. It should also be mentioned that the vaccine does not always provide complete resolution of pruritus symptoms. Thus, a third of the cats having had a favourable response to the desensitization vaccine will still need to continue medication to relieve their itching symptoms, but at lower doses.


The antipruritic most frequently prescribed by veterinarians is cortisone due to its low cost. However, this medication can cause serious side effects in the long term. Antihistamines can be added to try to reduce cortisone doses and therefore reduce short, medium, and long-term side effects. Fatty acids can also be added. Their main benefit is that they cause very few adverse effects, but they are not effective in all cases.In cases of acute attacks, a mild animal shampoo made with oats, aloe or coconut oil will have a calming effect and will eliminate allergens and microorganisms on the surface of the skin. Additionally, some topical products are formulated to help strengthen the skin barrier.

Other medications such as Apoquel (oclacinitib), Atopica (cyclosporine) and Cytopoint (interleukin-31 specific monoclonal antibody) are great options to consider in controlling your cat's pruritus symptoms. They are more expensive than cortisone, but they don't have the same long-term side effects. It is very important to remember that the medication will not cure your cat of his allergy but will make him much more comfortable.


Atopy and food allergies are conditions frequently encountered in our pets. If you think your cat is suffering from it, talk to your veterinarian, he will be able to accompany you and give you the best advice for their well-being!