How to do a food allergy elimination diet for your cat

Kate Kalcevich
Jun 30, 2017 · 13 min read

Does your cat have itchy skin, diarrhea or vomit regularly? These could be symptoms of a food allergy.

There are other illnesses that can cause these symptoms, so make sure your cat is checked out by a veterinarian. If your cat was diagnosed with food allergies, I can help!

I am not a veterinarian or nutritionist, just a cat owner for more than twenty years with an interest in keeping my cats healthy.

I use natural methods to treat my cat Leo’s digestive issues. He was vomiting up to 10 times a month when I adopted him as a kitten. He’s four years old now (2018) and is a healthy, strong, active cat who is thriving.

I’ve learned that by carefully controlling what he eats and adding a few supplements to his food, I can stop his chronic vomiting.

Food allergies are complicated to figure out. I couldn’t find a comprehensive resource on how to do an allergy elimination diet, so I decided to share what worked for Leo.

Quick start

Find a butcher where you can get pork shoulder or loin with no added sodium. Find out what day of the week pork gets delivered, ask to have 1pound of pork set aside and pick it up on the day it arrives or the day after (freshness is really important for an elimination diet).

Finely grind the pork in a food processor or chop it into very small pieces with a knife. Mix in enough water (1/4 to 2/3 cup) to create a texture like canned food. Divide the pork equally into two containers. Store one in the freezer and refrigerate the other.

Offer 1 teaspoon of the pork alongside your cat’s regular food. If your cat eats the pork, increase the amount by 1 teaspoon per day and decrease their regular food until they are eating only pork.

Feed only plain pork exclusively for 4 to 6 weeks. This is not a complete, balanced recipe — it is a bare bones recipe designed to eliminate all potential allergens.

Do not feed it to cats under 1 year of age. Do not feed longer than 6 weeks. If your cat improves while eating this recipe, you’re likely dealing with a food allergy or intolerance.

I’ve explained quickly how to do an easy allergy elimination diet so that you can get started right away. However, it’s important that you understand all potential complications so that you can do an effective elimination diet. Please keep reading to learn more.

Veterinary treatment

The standard veterinary treatment for food allergies is a novel protein diet which means feeding a type of meat your cat has not eaten before such as rabbit or duck.

Another option is to feed a special diet with hydrolyzed proteins where the food has been broken down into molecules that are too small to trigger an allergic response.

Why veterinary treatment may not work

I don’t personally recommend veterinary diets because cats with food allergies can have other complicating factors. Your cat may have an irritated digestive system from chronic vomiting or diarrhea. His or her immune system is overworked due to the constant consumption of allergenic foods that it considers toxins. When the immune system is on high alert, this is called inflammation.

If your cat has an irritated digestive system and his or her body is inflamed, anything that causes more irritation and inflammation can make things worse. My concerns with canned and dry food are:

  • you think you’re buying a novel protein, but in reality what’s on the label is not what’s in the food. Chicken is a common allergen for cats and it’s also the most common unlabeled ingredient found in commercial foods.
  • unnecessary ingredients are added for taste and texture including fillers, flavouring, thickeners and preservatives that irritate the digestive system
  • ingredients are added to save costs (meat is expensive!) that are not a natural part of a cat’s diet and are difficult to digest including grains, fruit and veggies
  • the manufacturing process destroys naturally present vitamins and enzymes in foods and artificial vitamins are added back to compensate (but not usually enzymes)
  • they often contain fish oils that could be rancid and inflammatory (high heat, exposure to air and improper processing or storage eliminate the healthy benefits of omega 3s) and fish is a potential allergen

If you still want to feed a veterinary canned or dry diet during the elimination trial knowing it might not work, scroll to the end of this article for my recommended product.

What to feed during an allergy elimination trial?

So what should you feed instead of canned or dry cat food? I suggest a home made recipe of a single novel protein. It could be raw or cooked. I prefer raw because it’s closer to the natural diet of a cat and has all the vitamins and enzymes naturally present in meat.

Homemade raw diets

An unbalanced diet fed long term can be dangerous to your cat’s health. It’s fine to feed during a 4 to 6 week trial, but please follow one of the well-known recipes I’ve included below or use a quality commercial raw food after the trial ends.

You can feed a whole prey diet of mice or other small birds and rodents that have been humanely killed using carbon monoxide from a reptile supply shop. This diet is balanced for long-term feeding because it’s a whole food — a natural source of perfectly balanced bones, meat, organs and the proper ratio of fat and protein for your cat. However, it can be very expensive (I pay $2.50 per mouse and would have to feed 5 per day)!

You can mimic a whole prey diet by feeding bones, meat and organs in the same ratio as a whole mouse at a much lower cost.

You can also grind meat, bones and liver together and add supplements to balance the diet. This is a good option if your cat won’t or can’t eat whole bones (i.e. has no teeth) or if you can’t source the necessary organs to balance the diet. Small bones can be ground in a blender while larger ones require a meat grinder.

Recipes for ground raw food (most of these are recipes for chicken, but you can substitute other proteins):

If you don’t want to grind bones or feed raw, consider a raw recipe that uses bone meal or eggshell powder or a cooked recipe with eggshell powder instead.

If you don’t want to buy the various supplements and measure them out, you can buy a premade supplement blend:

  • EZ Complete for raw or cooked meat (fish free, but contains egg, chicken liver and pork pancreas)
  • Alnutrin for boneless raw meat or meat with ground bones (fish free, but contains egg)
  • TCFeline Premix for raw meat (fish and egg free, but contains pork gelatin)
  • Hilary’s Blend for cooked meat (sold in veterinary clinics in Canada only and is meat, fish and egg free). Make sure to use recipes that don’t include veggies.

Commercial raw diets

There are some commercial raw foods that have limited ingredients and could be a suitable alternative to a homemade allergy elimination diet:

  • Rad Cat
  • Hare Today
  • Raw Feeding Miami
  • Big Country Raw in Canada. Farm Fest or Game Bird Blend are the cat specific formulas. They are not single proteins, but both are fish, egg and dairy free and I have one cat that does really well on Farm Fest and the other on Game Bird Blend. They also have a variety of pure proteins, but most are too high in bone content for cats and need to be balanced by adding extra boneless meat and organs (which is easy to do). Some cats can’t digest more than 10% bone and will vomit the excess bones or become constipated.

How to do an allergy elimination trial

The idea is to feed only one protein for 4 to 6 weeks to see if your cat’s health issues improve. I suggest using a novel protein that your cat hasn’t eaten before, if possible. I also recommend starting with either a red or white meat protein and if there is no improvement after the trial switching to the other type for another 4 to 6 week trial.

You must eliminate all potential allergens. This includes treats (unless you can get freeze dried treats made from the same protein you are testing), toppings like nutritional yeast, cheese, milk, eggs, bonito flakes, etc., and flavoured toothpastes. Your cat must eat only the single protein otherwise you can’t tell if he or she is reacting to the food or something else.

Create a symptom diary

During the trial, you’ll need to write down what you are feeding and what reactions your cat has. Here are some examples of various Google applications I’ve used to keep notes during allergy elimination trials.

Step 1: establish a safe protein (4 to 6 weeks +)

For example, you can feed only ground rabbit meat, bones and organs with taurine added for 4 to 6 weeks as a white meat trial. Rabbit is low in Taurine, so I would definitely add 250 mg Taurine daily if feeding only rabbit.

Pork, duck or lamb are good options for a red meat trial and no Taurine is needed since it is naturally present in the meat.

See the “What to feed…” section above for recipes.

Chicken, turkey and beef are proteins most cats have eaten before, so they aren’t good choices for novel proteins.

Step 2: add omega 3s (2 to 3 weeks)

After you establish a safe protein, I suggest introducing an omega 3 source for 2 to 3 weeks to see if that causes a reaction. Fish is a common allergen, so I suggest using krill oil or green lipped mussel to establish a non-allergenic omega 3 source. I’d try fish much later on, as a third or fourth protein trial.

Fish should never be fed exclusively. Only feed small oily fish occasionally for omega 3s if your cat can tolerate them (1 ounce per day per 35 pounds of body weight, which works out to 2 ounces per week for a 10 pound cat).

Fish oil or krill oil can also be fed instead of whole fish. Be aware that oils may be extracted using solvents which could be irritating to the digestive system. Whole frozen small fish is the source of omega 3 that is least likely to contain toxins. Some cats that are allergic to fish can tolerate fish oils, but mine can’t.

Step 3: add egg yolk (2 to 3 weeks)

Next, I would add in raw or cooked egg yolks to see if there is an egg allergy. Egg whites are more likely to be allergenic, so separate the whites and yolks and add ¼ egg yolk per day to one of your cat’s meals. You can safely leave the leftover egg yolk in a container in the fridge for the next 3 days. If you prefer to cook the yolks, boil the eggs and remove the whites. Do the egg trial for 2 to 3 weeks.

Egg yolks are an excellent digestive aid for cats. Choline and lecithin help to emulsify fats and increase digestive motility, preventing or reducing hairballs.

Step 4: establish a second and third safe protein (4 to 6 weeks)

Finally, introduce other proteins one at a time (for 2 to 3 weeks each) until you find all the proteins your cat tolerates. Once you’ve identified foods your cat reacts to, you’ll want to do allergen challenges to be sure what you can and can’t safely feed.

Step 5: Allergen challenges (1 day per challenge, 2 to 3 weeks in between)

In order to verify an allergy, you should feed the same item at least 3 separate times, with no other dietary changes. Sometimes a reaction could be just a coincidence or related to another factor (for example your cat nibbled on a house plant and vomited because of that).

It’s important to find at least 3 safe proteins to feed. Variety is key to ensuring your cat is getting the best nutrition and doesn’t develop any health issues due to dietary deficiencies. It also helps to have at least 3 options in case your safe protein is not available for some reason.

What if the allergy elimination trial doesn’t work?

If you tried a homemade or commercial raw diet and there were some potential allergens (fish, dairy, pork, eggs), you should try a more simple elimination diet of pure raw meat, bone and organs or a single cooked protein only to ensure that your cat is not reacting to any other potential allergens.

Your cat may also have another complicating issue in addition to food allergies.

If you’ve done a full allergy elimination trial and your cat still has itchy skin, consider that there might be an environmental allergy and talk to your vet about allergy testing and treatment.

If you’ve been to the vet and completed a full allergy elimination trial and your cat still has diarrhea, consider using s. Boulardii probiotic and slippery elm bark to treat diarrhea.

Impaired digestive motility

If you’ve done a full allergy elimination trial and your cat still is vomiting, he or she may have a motility issue. The digestive system may not be moving food along as quickly it should and food sits in the stomach or intestines for too long and then comes back up as vomit.

With impaired motility, fur often clogs the digestive system — even if your cat doesn’t vomit hairballs. Fur sticks to the fat in the food and makes little fur and fat clumps that partially block the digestive system. Food is often vomited hours after eating in this case. You can use hairball treatments to eliminate hairballs immediately and egg yolk plus egg yolk lecithin to increase motility and prevent future hairballs.

If egg yolks and lecithin is not enough, try adding a source of fibre like Vet’s Best Hairball Relief which has psyllium and apple pectin. Fibre has been clinically shown to increase excretion of hair in poop (which is where you want it coming out, not through the mouth!)

During shedding season, Leo gets 1/4 egg yolk, 2 capsules of egg yolk lecithin and 2.5 Vet’s Best pills per day to manage hair related vomiting.

If your vet has told you not to worry about hairballs or occasional vomiting, you should know that other veterinarians might have a different opinion.

Veterinarian Gary Norsworthy is “convinced that the vomiting of hairballs is a sign of chronic small bowel disease if it occurs twice a month or more in any cat; or if it occurs once every two months or more in shorthaired cats.”

Veterinarian Fern Slack agrees that “a hairball, far from normal, is probably a common early symptom of Inflammatory Bowel Disease.”

Histamine intolerance

I suspect vomiting could also be caused by a histamine intolerance. Histamines are neurotransmitters that are produced in the body during any allergic response. Histamine causes an immediate inflammatory response warning the immune system of potential toxins. Histamines can be absorbed from foods that are high in histamine, thereby mimicking an allergic response.

I would suggest a low histamine trial if you think your cat is reacting to any of these foods that are high in histamine:

  • fish that isn’t frozen right after catching and eaten the same day after thawing (histamine increases as the fish becomes less fresh)
  • certain fish are higher in histamine than others, including canned fish, tuna, anchovies, mackerel, salmon, and herring (frozen at sea sardines fed soon after defrosting are your best bet for low histamine and high omega 3)
  • meat that isn’t frozen soon after butchering and eaten within 2 days of thawing (histamine increases as the meat becomes less fresh, but less quickly than fish)
  • nutritional yeast (sometimes used as a source of B vitamins or as flavouring)
  • apple cider vinegar (often used as a health remedy)
  • beef sold in grocery stores and at butcher shops is almost always aged for two weeks
  • raw egg whites (a histamine liberator, it helps to release histamine from other foods)

According to this podcast, higher fat diets contribute to diamine oxidase (DAO) enzyme overuse in the small intestine. Since DAO breaks down histamine, there may be higher histamine levels. A moderate fat diet (12–15%) may be appropriate for a cat with histamine intolerance.

Fats

Some cats don’t do well on a high fat raw food diet. If you’re feeding fatty meats like pork and duck or white meats with skin and fat attached and your cat still has issues, try reducing the fat by feeding leaner meats like turkey and rabbit or by removing all visible fat and skin.

The optimum amount of fat to feed can vary for individual cats. A low fat diet may worsen constipation in some cats or cause dry, flaky skin. Too much fat may increase hairballs. You can try adjusting the amount of fat (doing 2 to 3 week trials) until you find a suitable balance for your cat.

Veterinary formula allergy diagnosis food

It can be hard to switch a cat to a new diet, especially if the cat is older and a finicky eater. If you don’t want to put in the effort to slowly transition your cat to a raw or home cooked diet, there is one novel protein diet that I consider the least worst of all the processed commercial foods: Rayne Rabbit-Diag(nosis) canned food. It can only be purchased from your veterinarian and is suitable only for short term feeding during an allergy elimination trial.

What do I feed Leo?

Currently, I’m feed Leo three times a day. His meals rotate through:

  • a commercial raw blend called Farm Fest by Big Country Raw which has beef, turkey and lamb
  • ground raw pure buffalo, rabbit, kangaroo or duck with bones from Big Country Raw combined with pure meat and organs from Tollden Farms to make balanced meals of 83% meat, 7% bone, 5% liver and 5% other secreting organs
  • a whole mouse as an occasional treat
  • crickets and pure freeze dried meat as treats

I supplement with:

  • 1 egg yolk per 1 pound of food
  • 1 teaspoon of green lipped mussel per 1 pound of food
  • a small pinch of a Taurine-Vitamin E blend that I make to ensure he’s getting enough Taurine because it degrades in frozen, ground meat and Vitamin E as an antioxidant to counteract the oxidation caused by feeding grinds. I mix 4 Taurine capsules with 1 Vitamin E capsule and keep it in a small baby food jar and add 1/4 teaspoon per 1 pound of food.
  • 1.5 capsules of egg yolk lecithin divided into three doses daily to increase digestive motility and prevent hairballs (I go up to 2 capsules daily during shedding season)
  • 2.5 Vet’s Best Hairball Relief pills daily during shedding season
  • ½ capsule of bovine colostrum in two doses of ¼ capsule daily during a herpes flare

This work is licensed under a Creative Commons Attribution 4.0 International License. That means you can quote it, copy it or rewrite it for either commercial or personal use and all I ask is that you provide a link back to this article.

Kate Kalcevich

Written by

Hearing impaired inclusive designer, public servant, biohacker, experimenter, trailblazer, ketogenic crossfitter, raw feeder, cat whisperer. Views are my own.

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