“What’s causing this rash on my cat?”
I see questions like this all the time on message boards and in my email inbox, accompanied by a blurry close-up photo of a bald haunch or a crusty chin. Well-meaning people attempt to answer, diagnosing everything from fleas to reactions to the food bowl to cancer. No one ever likes my answer, but it’s true: Any of the above and more.
The number of disease processes that lead to skin lesions in the cat is long. It’s also unpredictable: A food-allergic cat can have crusty ears or bald haunches or a bright red rash. For these reasons, it’s nearly impossible to make an accurate diagnosis without a veterinarian. The vet needs to take a detailed history of your cat, as well as perform a complete examination, before determining whether your cat is likely to have allergies — and if so, what kind.
Cat allergies are divided into four major categories. In order of their prevalence in juvenile cats, those categories are:
4. Mosquito bite hypersensitivity
Flea Allergies In Young Cats
Although all cats can react with discomfort to flea bites, cats with a true allergy can become tremendously uncomfortable from just one bite. This can fool people who think that, just because they don’t see an obvious flea infestation, fleas couldn’t possibly be the problem.
Such was the case with Willie, a 3-year-old Maine Coon who was rapidly losing his beautiful long coat. His owner felt convinced he had a metabolic condition that was causing his hair to fall out, but the evidence showed otherwise: His shortened fur had the tell-tale blunt edges of a coat that was being incessantly licked.
Willie’s owner had spent tons of money on a special diet for him and fought with him on a daily basis to get him to take Benadryl, but she drew the line at flea treatments.
“He doesn’t have fleas,” she said. “He never goes outside.”
“But you have a dog,” I reminded her. “And he goes outside, right?”
“Yes,” she said. “But the fleas don’t come in. It’s not fleas.”
Using a flea comb, I was able to comb out enough flea dirt from Willie’s fur to prove to his owner that even though we couldn’t see fleas on him, they were making an appearance. Grudgingly, she agreed to dose Willie with some Advantage, and voilà! Problem solved.
All things considered, Willie is lucky. Flea allergies are readily controlled with diligent flea preventives, and are thus much easier to manage than some of the other forms of allergic disease.
Food Allergies In Young Cats
Food allergies, the second most commonly diagnosed allergies in young cats, can pop up at any point in a cat’s life. Although a feline may have a reaction to any ingredient in pet food, proteins are the most common culprit. Beef, poultry and seafood — some of the most commonly used protein sources in cat food — are also the most frequently diagnosed reactive foods.
While skin issues such as itchy or crusty skin are the most common signs of a food allergy, it is not uncommon for cats to also display gastrointestinal signs such as vomiting or diarrhea when suffering from a food allergy.
Once a cat is diagnosed through a stringently implemented hypoallergenic elimination diet over 10 to 12 weeks, owners can isolate the offending ingredients by offering one at a time each week, and then selecting an over-the-counter diet that avoids that ingredient. Alternatively, owners can cook their own food at home; board certified veterinary nutritionists can develop a personalized recipe based on your own cat’s specific needs.
Environmental Allergies In Young Cats
Cats can also have environmental allergies to pollens, molds, mites and any of the sorts of inhaled allergens that also trigger hay fever signs in people. While the skin is usually the first organ to be affected in cats, it is not uncommon for felines to develop respiratory signs and even asthma secondary to allergies. Cats who live with smokers and are exposed to lots of dust and aerosols are more profoundly impacted and benefit greatly from a clean-air environment.
Contact dermatitis is a subset of environmental allergies where the allergen is not inhaled, but requires direct contact to trigger a reaction. We see this commonly with grass allergies on the feet and belly and with plastic food dishes, which can trigger lesions on a cat’s chin. Using glass or metal dishes can help, as can frequent bathing if you can do it without getting your hands shredded.
Mosquito Bite Hypersensitivity In Young Cats
Mosquito bite hypersensitivity may be a problem in your area, but it’s highly dependent on your geographic region as well as your cat’s lifestyle. Unlike fleas, which happily move in and make themselves at home in your upholstery and carpeting, mosquitoes tend to remain outside, and in a population where most pet cats stay indoors, they are less frequently exposed to the bug. Those who are reactive most commonly have lesions on their noses and ear margins.
Cats may be treated with feline-friendly mosquito repellent, but be sure to check with your veterinarian, as DEET-based products made for people are not safe for cats.
Clearly, allergies aren’t the easiest disease process to manage, but what else did you expect from a cat? They might drive us crazy, but they’re worth every bit of the effort.