Does Your Senior Cat Have Allergies?

It’s unusual, but even senior cats can suddenly develop allergies to foods and products they’ve been exposed to their whole lives.

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Extensive over-grooming may be a sign of allergies in cats. Vladimir Arndt/iStock/Thinkstock

When my cat Apollo was 11 years old, he went bald one night. All right, it might have taken a little bit longer than that, but it seemed to happen pretty quickly. One day he was a beautiful, glossy black cat, and the next he was a moth-eaten mangy mess.

The abruptness of this change took me by surprise. Apollo had no changes in his routine for years. He was an indoor cat, he wasn’t exposed to fleas and he had been on the same food all his life with no problems. But now, the fur on the entire bottom half of his body was licked off.

Allergies were not high on my list of suspicions, to be honest. I checked Apollo’s bloodwork to make sure he didn’t have a metabolic disease developing (he was getting on in years, after all). I treated him for parasites just in case I somehow sneaked something home from the clinic. He had a mild bacterial infection in his irritated skin, so I treated him with antibiotics. I gave him a dose of steroids, which should improve the symptoms of itching in most cats with irritated skin, but even that didn’t work.

At a loss and wondering if he had cutaneous lymphoma, I took a skin biopsy. The results, fortunately, did not find cancer, but rather, inflammation suggestive of allergic disease. Apollo hadn’t responded to steroids, which should improve symptoms in cats with two of the most common categories of allergic disease: flea and environmental allergies. That left only one thing: food.

It seems strange that a cat who has lived more than a decade, happily existing on the same routine, can all of a sudden become intolerant to his food, but that’s exactly what happened. Like me, many people who have senior cats who develop food allergies have a hard time thinking food could be the culprit, because nothing in their life has changed — but that’s exactly how it goes most of the time. Sometimes food allergies come up immediately, as soon as a cat is weaned. Other times, they take years to develop.

We started an elimination diet with a venison-based cat food. I made sure the diet contained a single novel protein and carbohydrate source. In other words, both the protein (venison) and the carbohydrate (peas) were ingredients Apollo had never had before, and they were not mixed in with other commonly used ingredients like beef or corn. His hair started to grow back within the month.

Once he was back to normal, I challenged him with ingredients to try and figure out what the exact culprit of his symptoms was. Like most food-allergic cats, he was reacting to proteins. As it turns out, both chicken and fish would trigger a recurrence of his licking. It was nearly impossible to find a commercial food without either of those ingredients somewhere on the list, so Apollo remained on venison for the rest of his life. He didn’t seem to mind.

Other causes of allergic disease exist in cats besides food. Environmental allergies, flea allergies and mosquito hypersensitivity can also play a role. Generally, cats with those types of allergies start to show signs before they reach their senior years, so I’ve learned over time that if a senior cat suddenly develops symptoms suggestive of allergic disease, I think about food first.

Allergic disease in cats tends to present as a skin problem: hair loss, extensive over-grooming and red or irritated skin. Secondary infection with bacteria and yeast is common. Other times, allergic disease can manifest with respiratory signs like wheezing, or gastrointestinal signs such as vomiting or diarrhea.

These are fairly non-specific signs that are also caused by many other medical issues in cats, particularly as our cats age, so it’s vital that you take your senior cat to the vet if he starts to show any of these symptoms. Food allergies can take up to 10 to 12 weeks to respond to a hypoallergenic diet, and you don’t want to lose all that time waiting for a change if the problem is something else entirely.

Treatment for allergic disease depends on the trigger. Flea allergy, the most common allergy in cats, is treated with stringent flea control. Food allergy is controlled with a diet. Environmental allergy, the least common of the three in the senior cat, is managed with a variety of medications from antihistamines to steroids or allergy shots. In all three cases, cats need to be monitored for secondary infections and treated with antibiotics or anti-fungal medications if needed.

Being a senior is hard enough. No one should have to deal with incessant itching on top of all the other indignities of aging. If you suspect allergies in your cat, give the vet a call — we’re here to help your beloved senior feline age gracefully.

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Article Categories:
Behavior and Training · Cats


  • My cat is probably 10-11 years old and she all of a sudden started getting scabs at the base of her tail, mainly. I took her to the vet and they gave her an antibiotic but due to the fact that she has all of her claws and that I can’t catch her, I can’t give her the medicine. But I’m wondering now if it is the food she is eating. I’m wondering, did you buy a certain kind of food or have you been cooking your cats food yourself?

    Kelsey Hoey March 16, 2017 9:46 pm Reply

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