Food Allergy
Food allergy is an uncommon problem in cats and it can start at any age. A change in diet is not necessary for
development of food allergy. About 70 percent of affected pets develop allergies to food ingredients that they
have been fed for a long time, usually more than two years. In fact, if your cat has an immediate adverse
reaction to a new food, it is probably not an allergic reaction, because it takes more than one exposure to
produce an allergic reaction. Food ingredients most commonly responsible for allergies are beef, chicken, fish,
eggs and milk. The tendency to develop allergies is genetically determined. Cats with other allergies like
inhalant allergies or atopy may be at increased risk for developing a food allergy.
The clinical symptoms of food allergy resemble those of other types of allergies. These two disorders may have
the same clinical symptoms and the same distribution of itchiness or pruritus over the cat's body.
Food allergy should be ruled out first because it is the easier of the two disorders to control by eliminating the
offending food ingredient from the cat's diet. Food allergy is ruled out by feeding a diet consisting solely of
food ingredients to which the animal has not been previously exposed – an elimination food trial. This trial
should be performed before considering expensive tests for other types of allergies.
What to Watch For
Itchy (pruritic) skin, especially around the face, paws and ears
Bad skin odor
Excessive scaling
Red bumps or papules
Ear infections
Self-inflicted skin trauma resulting from severe itching
Diarrhea and vomiting, although most cats with food allergy only develop skin problems
Flea Allergy Dermatitis
Flea allergy dermatitis is the most common allergy in cats and is caused by flea bites, specifically the saliva of
the flea. It is a very itchy disease and predisposes to the development of secondary skin infections.
Oddly enough, most animals with flea allergy have very few fleas – because they are so itchy, they groom
themselves excessively, eliminating any evidence of fleas. However, a couple of flea bites every two weeks are
sufficient to make a flea allergic cat itchy all the time. Any animal can become allergic to fleas, although some
cats are more attractive to fleas than others.
Fleas are bloodsucking insects with a life span of 6 to 12 months. This life span is influenced by environmental
conditions and can vary from two to three weeks up to a year. Optimal conditions include humidity of 75 to 85
percent and temperature of 65 to 80 degrees Fahrenheit. Humidity is more important than the temperature.
The adult flea spends most of its life on the host, while the immature stages (eggs) are found in the
environment.
What to Watch For
Severe itching
Chewing and biting of the tail, rump, back legs and occasionally front legs
Oozing lesions (lick granuloma) from chewing
Hot spots on the hips or face, which is severe skin damage from scratching
Atopy
Atopy is a pruritic (itchy) skin disease of animals that is caused by an allergy to substances in the environment
that are contacted through the air, either by absorption through the respiratory tract or contact through the skin.
Atopy is thought to be an inherited disease. It can be difficult to diagnose in cats and, therefore, is probably
under-diagnosed.
Symptoms of atopy usually begin relatively early in life, often by one year of age. Symptoms usually are
seasonal at first, with most cats showing clinical signs in the summer months when airborne allergens (such as
plant pollens) are present in higher concentrations. As atopic cats age, their symptoms tend to become less
seasonal as they become allergic to more substances. Eventually, their itchiness can occur year-round.
Cats with atopy are usually itchy, particularly the hands and feet. The skin may be red and irritated due to
scratching, and the ears may also be inflamed.
What to Watch For
Chewing at the paws
Scratching the muzzle or rubbing it on the ground or with the paws
Scratching the ears
Shaking the head