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what are food allergies in cats?
A food allergy is an adverse reaction that occurs when a cat’s immune system overreacts to a food substance to which it has been previously exposed. For a cat to have a food allergy to a specific ingredient, it must have eaten that ingredient in the past.
Food allergies most often affect the skin, causing itching, scratching, excessive grooming, secondary infections, and sores. food allergies can also disrupt the gastrointestinal tract, causing diarrhea and/or vomiting.
Food allergies are rare cats. it is estimated that only 1% of all cats have food allergies and up to 15% of cats have itchiness. of cats with itching and GI symptoms, up to 42% could be allergic to food. no relationship to age, sex, or race has been identified.
symptoms of food allergies in cats
the most common symptom of food allergies in cats is constant itching that doesn’t change with the seasons.
symptoms may also include:
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licking
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scratching
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excessive grooming
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bite
itching can occur anywhere on the body, but the head and neck are most affected.
Skin lesions may also occur, which may include:
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small scabs (miliary dermatitis)
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redness
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papules
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self-induced trauma (sores from biting, scratching, or licking)
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self-induced hair loss (due to biting, scratching, or licking)
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ulcerations
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plaques (raised circular nodules)
less frequently, there may be gastrointestinal symptoms, such as diarrhea and/or vomiting.
causes of food allergies in cats
Food allergies can develop at any age, even if a cat has been eating the same food for a long period of time without problems. Most known food allergies are due to an abnormal reaction to proteins in food. Below are some common foods that cause allergies, but food allergies in cats can be caused by any food substance and are not limited to these items.
The food sources that most commonly cause food allergies in cats are:
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beef
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fish
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chicken
Food sources that less commonly cause food allergies in cats include:
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wheat
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corn
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dairy
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lamb
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egg
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barley
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rabbit
how vets diagnose food allergies in cats
The gold standard for diagnosing a food allergy is to feed the cat a strict hypoallergenic diet for 8 to 12 weeks to assess for improvement in symptoms. this means that additional treats, flavored medications, or even certain formulations of medications (gelatin capsules) cannot be administered.
The food that will be considered hypoallergenic for an individual cat will vary depending on what foods the cat has previously eaten. Ideally, this is a home-cooked diet with a protein source the cat has never eaten before. there are many factors that make this difficult, and a diet of this type is not balanced for long-term eating.
If symptoms improve, the old diet can be reintroduced to see if symptoms return. if they do, the cat should be fed the hypoallergenic food again. after this, an individual ingredient can be introduced once every 2 weeks to see if symptoms worsen. if there are no symptoms, the cat is not allergic to this ingredient.
if symptoms appear within the next 14 days, the cat is allergic to this ingredient and should be avoided in the future. this is a trial and error process to determine the specific ingredients a cat may or may not be allergic to.
Alternatively, a new protein or hydrolyzed diet may be prescribed for the food elimination test. if improvement is noted, this diet is continued indefinitely. commercial diets such as these are formulated to be balanced for long-term feeding.
There are many types of tests on the market to diagnose food allergies. these may include collection of blood, hair, or saliva. however, none of these tests have been shown to be accurate in clinical studies.
It is important that you maintain a complete dietary history for the vet to monitor your cat’s response to a hypoallergenic food test. the choice of foods used during the trial will depend on this list. If you are on a novel protein diet, your vet will choose a protein source that your cat has never eaten before. even with hydrolyzed protein diets, it is preferable to choose one that is based on an ingredient that your cat has not previously been exposed to.
Some food-allergic cats that don’t respond to one diet may improve on another diet.
treatment of food allergies in cats
Treatment of food allergies in cats consists of feeding them a diet that does not contain any ingredients that cause allergies. the specific food sources you can feed your cat can vary greatly. Prescription diets are recommended when testing for hypoallergenic foods because they have more stringent quality control, while over-the-counter cat foods may contain contaminating proteins.
Most cats are very itchy when they start a trial of hypoallergenic foods, so symptomatic treatment may be necessary. low-dose corticosteroids, such as prednisolone, are often used for this purpose. any secondary bacterial or fungal infections should also be treated with antibiotics and/or antifungals, and repeat treatments may be necessary.
recovery and management of food allergies in cats
If your cat has a food allergy and is fed a suitable hypoallergenic food, it may take up to 10 weeks for symptoms to resolve. it is important to ensure that no other food sources are available during this time. food allergies require strict, lifelong dietary management. the supplements are not recommended for cats with food allergies due to the possibility of a reaction to them. they are also unnecessary, because these diets are formulated to be balanced and complete. if the symptoms are not controlled by a change in diet alone, other causes of the symptoms should be investigated.
Veterinary prescription diets used for food allergies include the following:
new protein foods for cats
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royal canin rabbit, duck or deer
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hill’s d/d (duck or venison)
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blue buffalo np (based on alligator)
hydrolyzed cat food
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purina ha (soy based)
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royal canin ultamino (bird feather based) or hp (soy based)
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z/d de hill (based on chicken liver)
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blue buffalo hf (based on salmon)
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