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What are Food Allergies?

Food allergies develop over extended periods of time, sometimes as long as months or years. Exposure to certain foods may cause the immune system to build a defense against a specific protein or carbohydrate molecule over time. The skin irritation caused by most food allergies may prompt a cat to harm itself from over-scratching. This can leave the cat vulnerable to secondary bacterial infections of the skin. Veterinary attention is needed to help identify the allergen and eliminate the corresponding symptoms.

Food allergies or intolerances happen when the immune system overreacts to a certain food item after it has been eaten. Antibodies respond to the food item, which often leads to “leaky gut syndrome,” and produces symptoms such as skin irritations or gastrointestinal issues. Food allergies make up the third most commonly occurring allergies in cats. 

Food Allergies Average Cost

From 575 quotes ranging from $200 - $800

Average Cost

$400

Symptoms of Food Allergies in Cats

One major indication that a food allergy is present is the continuation of symptoms year-round. Certain symptoms can prove threatening to the cat’s overall health and should be addressed promptly. Symptoms are as follows:

  • Itchy or irritated skin
  • Fluid-filled lumps on the skin
  • Head and neck skin issues
  • Weight loss
  • Anorexia (food avoidance)
  • Vomiting
  • Diarrhea
  • Hair loss
  • Dull coat
  • Inflammation
  • Ear infection
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Causes of Food Allergies in Cats

The exact reason a food that has been consumed for some time can develop into an allergen is unknown. There seems to be no link between breed, age, or sex of a cat and the occurrence of food allergies. More often than not, a low-quality protein source may be found as the allergen. Possible causes include:

  • Common food ingredients in cat food such as beef, lamb, corn, rice, soy, gluten, potato or dairy products
  • Preservatives
  • Biologically inappropriate ingredients (foods that cats don't naturally eat)
  • Dyes
  • Flavor enhancers
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Diagnosis of Food Allergies in Cats

To determine what allergen is causing symptoms in your cat, the veterinarian will need to perform a physical examination. You will be asked about the cat’s diet, including how long it has been given its typical food. The vet will have to differentiate between food allergies and other common allergies in cats, such as insect bites. Mange and infection will have to be ruled out or treated if also present.

The best way to diagnose a food allergy is to implement a “novel diet”, which uses the process of elimination to identify the allergen. The cat will be switched to a strict diet of two foods (one protein and one carbohydrate) that it has never eaten in its lifetime. For eight to ten weeks, the cat will remain on this simple diet until all previously seen symptoms have vanished. At that point, one new food item may be introduced. If no symptoms occur in the following two weeks, it is safe to assume that food is not the allergen. If symptoms do arise, the allergen has been identified. Additional food items may added in this fashion. This is a lengthy process that requires patience to be successful.

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Treatment of Food Allergies in Cats

Once the allergen has been identified, it must be permanently excluded from the cat’s diet. Abstaining from that food is the only long-term solution to stop symptoms from coming back. 

Specialized Diet 

Your veterinary nutritionist may develop a specific diet tailored to your cat’s needs. Generally, a diet that is low in carbohydrates and high in good quality protein is preferred. This diet may have two to three protein sources that do not irritate the cat. You will need to rotate the protein type every three to six months to help prevent more food allergies forming in the cat. The diet may be commercially prepared or it may have to be homemade.

Antihistamines 

To provide relief of symptoms immediately, antihistamines may be administered. This is only a short term solution, but may be necessary if the cat is suffering. 

Antibiotics 

If a secondary bacterial infection is present in the skin, an antibiotic may be prescribed to rid the body of the harmful bacteria. Prescriptions generally range from two to four weeks.

Probiotics 

Once the new diet is started, probiotics can be helpful in aiding food digestion. They can restore the good bacteria that the gastrointestinal tract needs to function properly.

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Recovery of Food Allergies in Cats

If food allergy symptoms do not disappear in the eight to ten weeks after diet introduction, see your vet to ensure diagnosis is correct. Once a cat is allergic to a food item, the allergy will almost always remain unless the gastrointestinal tract detoxifies and heals. If the novel diet seems to be working for your cat, stop introducing foods after you have found two or three protein sources that do not cause symptoms. If new food allergies start to develop, a diet change may be needed again.

To prevent food allergies from occurring in the first place, try to feed your cat a species-appropriate diet. Avoid low-quality protein sources such as hooves or beaks. Grain fillers can also be excluded as they do not nutritionally contribute to a cat. Work with a cat nutrition specialist when forming a standard diet for any cat.

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Food Allergies Average Cost

From 575 quotes ranging from $200 - $800

Average Cost

$400

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Food Allergies Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Bengal Cat

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Six Years

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Unknown severity

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0 found helpful

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Unknown severity

Has Symptoms

Ear Itching

Recently adopted (4/30/2020) female cat has gotten an ear yeast infection and 2 regular (bacterial) ear infections in about 3 months, and has been treated for all three. Previous owner neglected vet care for the 4 years of ownership prior, and cat had severe dental problems resulting in 6 teeth being removed in late June. The cat keeps getting specifically-ear problems, and doesn't show any other signs of a food intolerance or allergy/reasoning as to why this keeps happening. Her food and her litter have not changed/changed drastically. Any help would be appreciated.

Aug. 6, 2020

Owner

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Dr. Michele K. DVM

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0 Recommendations

Thank you for your question. She may have an anatomic change in her ear canal caused by chronic ear infections that is making it difficult to keep the infections from recurring. She may have a resistant bacteria that is not completely being destroyed by the antibiotics. The things that I would do next at this point would be to do a culture and sensitivity of the ear infection, to see if there are resistant bacteria, and possibly a sedated ear exam so that your veterinarian can see if there are abnormalities in the ear canal that are making this become such a problem. I hope that all goes well for her.

Aug. 6, 2020

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Tater Tot

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Persian Ragdoll

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12 Years

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Moderate severity

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0 found helpful

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Moderate severity

Has Symptoms

Raw Puffy Skin, Swollen Eyes

My cat has hair loss which started above his eyes and has now moved towards his ears. It is raw looking and swollen with little scabs.It started about a week ago. I did switch him to grain free dry food yesterday to see if that helps, in case it might be food allergy.

May 17, 2018

Tater Tot's Owner

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Dr. Michele K. DVM

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1611 Recommendations

Skin lesions in cats can be caused by bacterial infections, fungal infections, parasites, allergies and cancer. Without seeing Tater Tot, I can't say what might be going on with him, but if it doesn't improve over the next few days, it would be a good idea to have him examined by a veterinarian to make sure that he doesn't need any other treatment. I hope that all goes well for him!

May 17, 2018

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Schmittsen

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DOMESTIC

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7 Years

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Moderate severity

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1 found helpful

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Moderate severity

Has Symptoms

Scabs, Scratching,Licking,Hairloss

Hello, My cat is eating same type of food for several years now, dry and soft food and always products made from different type of fish as she didn't want to eat anything else (Purina One dry food and soft food Purina Gourmet). She never eats homemade food or raw meat od dairy products. I have changed her dry food to Purina sensitive (chicken)for a quite a long time now as I have noticed scabs on certain parts of her body. She was never ill before except once when she couldn't eat anything as her nose was blocked from cold but antibiotics have sorted that out. The problem with my cat is that she has developed scabs above the tail which go along the spine in different places( like 10cm diameter),small lump on her cheek and under neck,some loss of hair on the inside of her back legs and she is constantly licking and scratching those places(I suppose that is why she has scabs). She doesn't have flees as I have treated her regularly. I have never given her anything against parasites because she is mainly indoor cat but sometimes stays outside at summer time. Maybe that is mistake. Her stool is fine for what I have noticed and she always has fresh food and water. I have her for 5 years now and she was stray cat but sterilized too when she came to me but she never had any problems before. I believe that food might be the cause but it is just my opinion and I am not an expert. Can you please give me some advice which food to use because otherwise she is ok and eats like she doesn't have any problems except for these symptoms. I am very worried about her.Also I have noticed that most food contain fish parts or soy which might be the cause of problem. Please give me some advice as I can't afford to go to vet but I am willing to buy any kind of food that might help. Thanks a lot, Jelena

Feb. 20, 2018

Schmittsen's Owner

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Dr. Michele K. DVM

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1611 Recommendations

Thank you for your email. Flea and environmental allergies are actually much more common in cats than food allergies, and they can all be difficult to diagnose. It really would be best to have Schmittsen examined by a veterinarian, as it may end up costing you less in the long run then the foods that you are trying. One thing to start with is to have her on monthly prescription flea control, as many cats have flea allergies, and you may not even see the one flea that starts the reaction. She may have a bacterial or fungal infection that needs to be treated, or a parasite called Demodex. Once all of those things havve been ruled out, your veteirnarian can guide you to food choices, as there are many limited antigen diets that can control food allergies, but they do tend to be prescription. It will be much less frustrating for you, and uncomfortable for her, to seek the advice of a professional. I hope that all goes well for her.

Feb. 20, 2018

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Roca

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American Shorthair

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4 Years

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Moderate severity

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Moderate severity

Has Symptoms

Hair Loss

My cat is on a grain-free diet in dry food and wet food since she has had issues with hair loss before. Now it is more pronounced...mostly on the hind quarters and legs. She is not itching and has good appetite and energy level. I have a vet appt next saturday, just checking to make sure I need to make the hour and a half trip both ways with both my cats for sure.

July 26, 2017

Roca's Owner


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3320 Recommendations

There are numerous causes for hair loss in cat including parasites, food allergies, environmental allergies, hormonal disease, behavioural issues or infection. You would need to visit your Veterinarian for an examination as well as skin scrapings and possibly blood tests in order to determine a diagnosis. An examination of hair around the affected area will show (when examined under a microscope) if the hair is falling out or being groomed out, just because you don’t see the excessive grooming, doesn’t mean it isn’t occurring. Regards Dr Callum Turner DVM

July 26, 2017

Our cat Lola had a bacteria infection in her stomach which she was piscribed antibiotics by the vet . We did X-ray and there is no cancer or major issues. We started her on this new diet by the vet which she hates do we went back to her old food and she stated to throw up again . Don’t know what I should do ! Please help !i have already spent 1000 on the vet bill and can not afford it any more 😢

Sept. 25, 2018

Tala H.

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Mr peabody

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Shorthair

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4 Years

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Moderate severity

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Moderate severity

Has Symptoms

Itching
Itching Licking Scabs

Mr Peabody has definitely gone from everything from steroids to antibiotics to Lyme dips. The vet gave us the hills zd food which she has been on for 7 days....how long can it take for skin issues for clear up....she isn't getting worse but she is definitely licking some areas raw however she hasn't had any pustules etc. I have heard if it was a true food allergies it could take several weeks on the new food before we see skin improvements....is that true.

Food Allergies Average Cost

From 575 quotes ranging from $200 - $800

Average Cost

$400

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