Protein Allergy in Cats

A protein allergy will develop when your cat’s body becomes very sensitized to the protein sources in the food that he consumes. This can occur whether he eats commercial cat food or food that you cook at home. Proteins make up a large part of cat food and any cat can develop an allergy to proteins in the foods that he has consumed over time.

An allergy will occur to a protein in the cat’s food if his immune system has an excessive response to it. Should this occur, your cat’s skin will become itchy and inflamed and chronic ailments like wheezing and ear infections can develop. Cats may also experience gastrointestinal symptoms.

An allergy to a protein in a cat’s food can occur when the cat’s immune system overreacts to it at the time of consumption, releasing histamine to attack the proteins that are seen as “intruders”.

Should your cat develop an allergy to a protein that is present in his food, he may experience reactions in his skin. These include:

• Scratching, biting and/or licking his skin
• Hair loss
• Skin rashes
• Blisters/lesions or skin ulcerations
• Facial and limb swelling
• Hives
• Inflammation in his paws

Your cat may also experience respiratory symptoms like coughing and breathing difficulties and gastrointestinal symptoms like diarrhea and vomiting. Chronic ear infections and lethargy may also occur.

Types

There are a variety of proteins that can cause allergies in your cat. These include meat proteins, like beef, chicken and lamb, as well as non-meat items like eggs and dairy products.

An allergy to a protein in your cat’s food will occur when the mast cells that are present in your cat’s immune system overreact to the protein and mount an aggressive response to it, seeing it as an “intruder”. The mast cells’ role is to protect your cat from pathogens; when these cells are triggered by a substance, they will release a histamine. A histamine is a naturally occurring compound that will cause inflammation in tissues that it comes in contact with. It is this histamine that will lead to the allergy symptoms your cat displays.

Upon noticing symptoms in your cat, it is a good idea to take him to the veterinarian for a physical examination. Your veterinarian will ask you about the symptoms you have observed, when you first noticed them and any changes that have taken place. You will also be asked about your cat’s diet, how long he has eaten the food he consumes currently and any supplements and medications that he takes. Your veterinarian will conduct a full physical and upon viewing the skin symptoms in your cat, he will likely take a sample of his skin cells through skin scraping. This will allow him to view the cells under a microscope to see if there are any parasites, yeast or bacteria that may be causing his symptoms. Blood tests may also be conducted to confirm the symptoms your cat is experiencing are not a result of different diseases. Once those are ruled out, your veterinarian will consider possible causes of an allergic reaction. 

To determine the ingredients or foods that are causing an allergic reaction in your cat, your veterinarian will recommend an elimination diet. This will involve feeding your cat a relatively bland diet that is different from what he has typically been eating for 8-12 weeks. While your cat is on this diet, you will want to avoid giving him any table scraps, supplements or treats. Should the allergy symptoms clear up while your cat is on this diet, it will confirm that he was reacting to something in his prior diet. You can then reintroduce different aspects of his previous diet; should his symptoms return, what it is he is allergic to will be confirmed.

Once the allergy to a particular protein is confirmed, you will want to avoid feeding your cat that protein. Your veterinarian will help you to choose a diet that will meet your cat’s nutritional needs without leading to an allergic reaction. While your cat is still experiencing symptoms from the allergy, your veterinarian may recommend an antihistamine to see if it helps to minimize his symptoms. As antihistamines do not work in all cats, should it not be effective, your veterinarian may recommend corticosteroids to control the itching and inflammation that your cat is experiencing. 

Often, the excessive itching, biting and licking that results from the allergy will lead to your cat developing a secondary bacterial infection. Should this occur, your veterinarian will prescribe an antibiotic.

Should your cat develop an allergy to a protein in his food, his symptoms will resolve themselves once the protein is removed from his diet. It is important that you work closely with your veterinarian to ensure that his nutritional needs are met through his new diet.