Elimination diet for cats: how to do a diet trial
What is an elimination diet
What can cats eat on an elimination diet
How to do a diet trial in cats
What happens after the diet trial?
Diet Trials for Cats: Frequently Asked Questions
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Elimination diet for cats: how to do a diet trial
An elimination diet, also called a diet or food trial, can help your vet determine whether your cat's food is contributing to their skin or digestive signs.
It may be recommended for cats with symptoms such as overgrooming, head and neck scratching, recurrent ear infections, or chronic loose stools. A diet trial usually lasts up to 8 to 12 weeks, so patience is needed, but it is an important step when investigating ongoing skin or digestive problems in cats.
Blood and saliva “allergy tests” for food can produce both false-positive and false-negative results, so they are not considered reliable for diagnosing food allergies in cats. A properly performed diet trial is the most reliable way to investigate whether your cat’s symptoms are caused by an adverse food reaction.
What is a diet trial for cats?
Why? A diet trial may be recommended if your cat has a suspected food allergy or intolerance. Possible signs include excessive licking, overgrooming, hair loss, scratching around the head and neck, recurrent ear infections, vomiting, or chronic loose stools.
A diet trial means feeding a specific food for a set period, usually around 8 to 12 weeks, to see if symptoms improve. The trial needs to be continued for several weeks because it can take time for your cat’s symptoms to settle after a suspected food trigger is removed. Digestive symptoms often improve sooner, while skin symptoms can take much longer to improve.
Diet trials need to be done with strict supervision. No treats, milk, table scraps, other foods, or extras should be given, as this can affect the results.
During a diet trial, your cat should be fed food containing ingredients that they haven’t eaten before, using a novel protein diet or a hydrolysed diet.
What food to use for a diet trial
There are two main options for diet trials:
Novel protein diet: Using a food source that your cat has never been exposed to before. This usually means feeding a less commonly used protein such as venison, duck, or rabbit, depending on your cat's previous diet.
Hydrolysed protein diet: Hydrolysed diets contain proteins that have been broken down into smaller pieces, making them unlikely to trigger an immune response.
Home-cooked diets may be an option for some cats, but these must be formulated by a veterinary nutritionist to make sure they provide all of the essential nutrients your cat requires.
Veterinary diets commonly used for food trials
Your vet can discuss the best option for your cat, based on their lifestyle, age, food texture preferences (wet vs. dry), previous diet, and any other health conditions.
This may include:
How to do a diet trial in cats
Diet trials should be performed under veterinary supervision. This is important for selecting the correct food for your cat and carefully monitoring their symptoms. Your vet will usually rule out other conditions that can cause similar symptoms first, such as a flea allergy.
Select the appropriate food for your cat after discussing the options with your vet.
Transition your cat onto their diet trial food slowly, over 5 to 7 days (or longer if your cat is particularly fussy), to prevent tummy upsets or food refusal.
Feed the diet trial food exclusively for the period recommended by your vet (usually around 8 to 12 weeks).
Do not feed any treats, dental chews, or table scraps during the diet trial. Keep outdoor cats indoors if possible, or monitor them closely to prevent hunting or eating food from neighbors. Talk to your vet if your cat is taking flavoured medication, as this may affect the trial. Make sure all family members and visitors are aware of the rules, as a small slip can cause a big setback.
Keep a diary of your cat’s symptoms, including the severity of their scratching, grooming habits, skin lesions, stool quality, vomiting episodes, and energy levels. This helps you and your vet track any changes.
Reintroduce previous foods if symptoms improve: If your cat’s symptoms settle during the trial, your vet may recommend reintroducing their previous food to see if symptoms return. Your vet may also recommend adding individual ingredients one at a time, such as chicken then fish, for around 2 weeks each to help identify specific triggers. If your cat’s symptoms return with previous foods or individual ingredients, this strongly suggests that your cat has a food allergy or sensitivity to those items.
What happens after the diet trial?
If your cat’s symptoms improve during the trial and return when their previous food is reintroduced, this suggests that their food was contributing to their symptoms.
Once you know what ingredients your cat reacts to, you can choose a complete diet that permanently avoids those triggers. Cats with food reactions usually need to avoid their trigger ingredients long term.
If your cat’s symptoms do not improve with an appropriately performed diet trial, your vet will start looking for other underlying causes, such as environmental allergies (atopy).
Diet Trials for Cats: Frequently Asked Questions
Q: Can my cat have dental treats or catnip chews during a diet trial?
A: No. Your cat should not have treats, chews, milk, table scraps, or any other foods during a trial unless your vet has specifically approved them.
Q: What if my cat catches a mouse or eats something they shouldn't during the diet trial?
A: Contact your vet and tell them what your cat ate. Depending on what was consumed and where you are in the trial timeline, your vet can advise if the trial period needs to be extended or restarted.
Q: How long does a diet trial take?
A: Most diet trials last 8 to 12 weeks. Digestive symptoms, such as loose stools or vomiting, often improve quickly within 1 to 2 weeks. Skin symptoms, like itching, overgrooming, and ear infections, take much longer to resolve. Your vet will help guide you on this timeline.
Q: How can I tell if a diet trial is working?
A: If your cat has a food allergy or intolerance, you will notice their symptoms gradually improve during a properly performed elimination diet. Keep a detailed diary of their grooming behaviour, skin condition, and digestion throughout the trial so you can compare how they are doing before and during the diet.
Always work with your vet when changing your cat's diet. They'll make sure the food is safe and nutritionally complete.
Our Joii Vets are available 24/7 for advice.
