Three Top Allergens: Food, Fleas and Airborne Substances

Diagnosis and treatments for allergic cats can often be difficult or at least more difficult than in dogs. To rule out food allergy, the patient has to eat a carefully selected diet for four or more weeks. Its usually no problem to get a dog to eat the new diet but the same cant be said for the cat.

Food Allergies Can Mimic Skin Conditions

“Incidence figures on food hypersensitivity in cats are hard to find, since cats often won’t eat the special diets needed to either diagnose or treat food hypersensitivity,” says dermatologist William H. Miller, VMD, at Cornell.

Cats with a suspected food allergy usually visit either the gastroenterologist or the dermatologist, but not both. “Animals with vomiting and diarrhea rarely have skin issues associated with their diets and those with itchy skin rarely show signs of vomiting and diarrhea. But from the veterinary dermatologist’s perspective, the itching caused by food allergies can mimic that seen in scabies, flea allergies, environmental allergies or any number of other itchy conditions,” Dr. Miller says.

Cats with food allergies may continually scratch their head and neck, develop tiny crusted lesions over their bodies (miliary dermatitis), lick off their fur or develop larger sores (eosinophilic granuloma complex). These symptoms can also be seen in cats with other allergies. Any cat with a chronic GI or skin condition should see a veterinarian.

Diagnosis: “There is no reliable blood or skin test for food allergies in cats,” Dr. Miller says. “The diagnosis is tentatively confirmed by changing the food to some very well-selected novel or hydrolyzed diet and seeing if the clinical signs disappear. If the signs disappear, then the old food is reintroduced to see if the signs recur. If they do, then the diet is implicated.” However, “Because of cats’ general reluctance to eat new foods, allergy testing isn’t commonly done on cats.”

Treatment: “Cats can be reluctant to change their diet. If an owner is unwilling or unable to do the dietary elimination correctly, then medications used to treat itchy cats can be tried,” says Dr. Miller.

Prognosis: “Excellent. It is very rare for the food-allergic animal to become allergic to new foods as years go by,” he says.

A Flea Comb and Lesions Can Be the Best Indicators

A cat with flea allergies will often chew, lick or scratch at his abdomen. back, legs, tail base and nape of the neck. “A skin examination will reveal red papular (rash-like) lesions resulting from the flea bites,” says Dr. Miller. “With careful inspection or the use of a flea comb, flea feces in the form of tiny black specks, also called flea dirt, or fleas themselves will also be found.”

Diagnosis: If the cat is very itchy and has significant skin damage, a trip to the veterinarian is indicated to get medications to stop the itching and control the fleas. Although blood and skin tests are available, Dr. Miller believes they usually aren’t necessary. “The clinical evaluation is good enough, provided that the owner doesn’t bathe the animal or treat him for fleas right before taking him to the veterinarian.”

Treatment: “If the skin isn’t too bad, owners can try to solve the problem by designing their own flea-control program by buying products online or in pet stores,” says Dr. Miller. “However, owners should be aware that some products really don’t work and that pet store employees may not know much about the products.”

Alternatively, a wide variety of topical (spot application or collar) and systemic (orally administered or absorbed through the skin) products can be recommended by your veterinarian. “The best ones to use are determined on a case-by-case basis,” says Dr. Miller.

Prognosis: With good flea control, the prognosis for a flea-allergic cat is favorable. “The temptation is to stop flea control after a couple years when fleas aren’t seen,” Dr. Miller says. “But owners need to remember that fleas can reappear at almost anytime.”

Airborne Allergies Show Up as Persistent Itching

Cats with allergies to mold, pollen and other airborne particles primarily manifest itchy skin, says Dr. Miller. “Any persistent itching or any itching severe enough to create sores warrants a trip to the veterinarian.”

Diagnosis: “It is tentatively made when elimination of all the other probable diagnoses — via flea control, infection control and dietary testing — do not change the pet’s itching. Allergy testing can be done, but this is used to identify the agents that the cat is allergic to, rather than to diagnose an environmental allergy itself,” Dr. Miller says.

Treatment: New medications for environmental allergies in cats are appearing, Dr. Miller says. “These usually have fewer side effects than conventional medications and are often very effective. However, they can also be very expensive.”

Prognosis: Cats allergic to airborne substances may be plagued by skin problems throughout their lives, as with all other allergies.