How to do a food allergy elimination diet for your cat
Updated: December 2023
Does your cat have itchy skin, diarrhea or vomit regularly? These could be symptoms of a food allergy.
Other illnesses 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 thirty 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 nine years old now (2023) and is a healthy, strong, active cat who is thriving.
I’ve learned that by carefully controlling what he eats and when I can minimize 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. Finely grind 1 pound of 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, you must 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 homemade 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.
Option 1: 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)!
Option 2: 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. This is what I do. I make sure there’s a high volume of red meat and heart for taurine and then feed 7% bone, 5% liver, 5% other organs and the rest is meat.
I fed this diet for many years with no issues, but I now add kelp as a source of iodine as my cats are aging and green tripe as a source of manganese. Also, I’ve swapped bone for eggshell to lower the phosphorous levels in the diet and protect their kidneys in their senior years.
Option 3: You can also follow a recipe for ground raw food with supplements (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. Skip the supplements in these recipes for the first six weeks to ensure a proper elimination trial — otherwise, there are too many potentially complicating factors.
Option 4: 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)
Option 5: Some commercial raw foods have limited ingredients and could be a suitable alternative to a homemade allergy elimination diet:
- Hare Today in the US
- Raw Feeding Miami
- Bold by Nature in Canada
- Totally Raw in Canada
- Tollden Farms in Canada
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. Pork seems to work either way — it’s almost a mix of red and white meat, pink meat if there was such a thing.
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 toothpaste. Your cat must eat only the single protein otherwise you can’t tell if they are 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 pork, bones and organs with taurine added for 4 to 6 weeks as a 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 (sardines canned in water) 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.
I’ve been feeding Leo for many years with no omega-3 supplements. I make sure he’s fed good quality meats that are low in omega-6, offsetting the need to include omega-3 for balance.
Step 3: add egg yolk (2 to 3 weeks)
Next, I would add 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. Egg yolks are also highly nutritious.
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)
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).
Try to find two safe proteins to feed. You don’t want your cat to get used to only one protein and refuse to eat anything else. You might be unable to source that protein or if it’s a commercial food the manufacturer could go out of business. You don’t want to get stuck with no food options.
Note that my cats only eat beef. Now that I’m making food myself instead of feeding commercial raw food, I don’t have the challenges I used to have with sourcing proteins. There are also humans thriving on carnivore diets based solely on red meat so I feel comfortable feeding that to my cats. It’s also what they would eat if they were wild. You can’t find white meat in a forest.
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 as 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 are 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!)
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.”
Acid buildup
On a raw diet, a cat’s stomach is more acidic than on a dry or canned diet. This is their natural state. If they are used to being fed at certain times during the day, acid production will ramp up in anticipation of eating. If they don’t get fed at that time, they can vomit due to too much acid.
Sticking to a regular feeding schedule can help. If timing is off on a meal, you can give a few freeze-dried treats 20 minutes before the meal. If they have too much acid, they’ll throw up the treats and then you can feed the meal.
I always give freeze-dried treats before breakfast. It’s the meal that has the longest gap from the prior meal and it helps settle their stomachs 45 minutes before eating.
Fats
Some cats don’t do well on a high-fat raw food diet. If you’re feeding fatty meats like certain cuts of pork, 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. I feed my cats extra lean ground beef. They do better on that than lean ground beef.
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 bad 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 feed Leo three times a day and he only eats my homemade raw beef recipe:
- 1/2 tsp seaweed
- 1.5 tsp eggshell powder*
- 1kg extra lean ground beef
- 0.5 lb organ blend
- 0.25 lbs green tripe
* Save rinsed clean eggshells. Let them dry completely then blend in a blender and let sit for 5 minutes so dust settles before opening.
For treats, he gets:
- a whole mouse occasionally
- pure freeze-dried meat as treats (beef or duck)
I don’t add any supplements to his meals.
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.
