Cat's Sore Could Be Food Allergy

Cats can get "hot spots" like dogs. Our veterinary expert explains what causes cat skin outbreaks.

By Arnold Plotnick, DVM | Posted: August 23, 2012, 4 p.m. EST

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Cat With Food Allergy at Dish
A food allergy can cause a skin outbreak in cats.
Q: My 3-year-old cat has a persistent sore on her upper back. We have taken her to the vet three times now. She was treated with antibiotics and cortisone shots as well as flea treatment. The sore persists although it is now dry and scabbed over. Can we do anything else for her? The vet did not know what could cause this; maybe a food allergy although she has not been given any new foods.

A: Many cats with skin allergies will develop a large circular red sore on their back, often right in the middle of their back in the shoulder blade area. Often, the sore will ooze a little serum, and it can sometimes become infected. These are similar to “hot spots” that commonly develop in dogs. A few things can cause them.

Inflammatory or Auto-Immune Condition Anti-inflammatory medication — steroids such as prednisolone, a synthetic version of cortisone — often cause the sore to resolve. I personally prefer to prescribe tablets rather a steroid injection, as I feel it is safer. Steroids didn't work, so an inflammatory or an auto-immune condition seems unlikely.

Bacterial Infection If a secondary bacterial infection develops, it might need antibiotics. Antibiotics didn't work, so an infection is unlikely.

Flea Allergy Cat flea allergy can certainly cause scabs throughout your cat's skin, but usually doesn't cause a persistent open sore. Flea treatment didn't help, so fleas are unlikely to be the cause.  

Food Allergy Cat food allergy can present in a variety of ways, although a persistent sore is not your typical presentation. I'm surprised that the steroid injections had no effect. The next step is to determine whether your cat has a food allergy.

How to Determine Whether Your Cat Has Food Allergies
•    Start a hypoallergenic diet. A hypoallergenic diet contains a protein source that your cat has not been exposed to before, such as rabbit, venison or duck. (Most veterinarians carry prescription diets designed for this purpose.)
•    Feed this food, and ONLY this diet, for up to 10 weeks, before concluding whether or not food allergy is the culprit.
•    Alternatively, you may opt for a skin biopsy. This simple procedure will very likely reveal the diagnosis. 

Considering the number of treatments that you've tried with no success, I think you need a biopsy at this point. Another option would be to consult with a board-certified veterinary dermatologist. Your veterinarian can direct you to an appropriate referral center.
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JOY    pittsburgh, PA

6/28/2016 2:44:14 PM

George is our 4yr old Ragdoll..100% indoor..last yr developed a wound(looked like a chunk of fur was drainage,,just naked pink skin) between shoulder blades, we thought he may have got stuck under a couch in the we blocked it off,,a few weeks later, another open area on the one shoulder area, and started acting "irritated".so to the ER VET.was told food allergies (was already on a special diet for stones), so we had to find a food that was hypoallergenic and that had a LOW "SO" urinary content so we used Royal Canin hypoallergenic worked! we did the 8 wks of only that food and then every once in a while he gets a "NOVEL" protein like rabbit, venison or duck as a treat, they are wet foods...NOW Royal Canin makes duel diagnosis foods for pets w multiple issues like stones and allergies ) thank u)

Edith    International

6/28/2016 8:31:45 AM

My cat has had a small sore in her nose that never heals since the day I adopted her, however, I am scared of a biopsy because her nose is so small and I am afraid they could hurt her. Is there a way to make a biopsy that is less invasive?

INGIBJORG    International

10/7/2015 3:46:09 AM

My cat did lick her self big time and get no hair on many spots ..then she started getting like excem (may be wrong spelling) around her mouth and no other cats was having this..had many at that time..anyway she got lost for many months and when she came back she had BIG time excem on her back between the shoulder blades -behind ears- on the top of her forehead -under the chin - around her mouth and it reached almost to her eyes..even on the back of her back feet ..but it was worst in the other areas..She looked like she had been fed.. she was not thin but she was lost for 6 month..I thought she was dead...anyway..I I did wash her scabs just with water then adding organic coconut oil on it all rub into her sores she did bleed some places and she would lick the coconut of but that is ok..and then I did take the gel from my Aloe Vera plants and smear it on her sores well..She was looking like I describe in 31 May and now she have totally healed but I also changed food 2 months ago got food with no MSG- no additives- no chicken only lamb meat and no flour-no soy..I do not have the name here but it is German organic food. My sons also started their cat on same food and wow what a change happened in them also..son of this lady cat was always skinny no matter what and also showed a bit like excem around his mouth ..he look so healthy now his fur is shining and he is more calm no excem and the lady cat they own also made big changes she - is was always very small -born in 2011 but in these 2 months she have grown bigger! But for my lady cat - I think the coconut oi and Aloe Vera made the start healing - but it not wet totally away but got big time down was got until I got this food.. I have to ask my sons what the name of it is..the bag is with visit to the vet ..nothing like that.. So..and other..I m against vaccines both for humans and animals so my cats never get that so they are not getting allergic from the vaccines...

Angie    Windsor Mill, MD

6/10/2015 6:56:56 PM

Good article. Good advice. In February, my 3 year old Aby suddenly developed a round, raw wound on his right neck. The vet believed it was related to a problem with his teeth. So I paid the $600 for dental work. But a couple weeks later, the wound returned. This time I immediately knew the culprit - his food. I've always fed my cats Wellness Cubed Chicken Entree. But this year, the store has sometimes been out of the food. My last trip to purchase cat food, I'd bought Wellness Minced Chicken Entree. The same thing had happened in February. I returned unused cans of Wellness Minced Chicken Entree and will never purchase it again. I have no idea why the Minced version is a problem. Recently, I've switched to feeding my cats more of a raw diet. I feed either Primal Freeze Dried Turkey or the Freeze Dried Chicken with Salmon foods mixed with a little of the Wellness Cubed Chicken Entree. The Aby hasn't had any further problem and both of my cats have very healthy looking coats. Surprisingly better than when they ate only the Wellness Cubed.

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