Food Intolerance in Cats: What Every Owner Needs to Know
Disclaimer: The following article is for educational purposes only and should not replace veterinary advice. If your cat shows signs of illness, always consult a qualified veterinarian.
Introduction
When we think about food sensitivities, most people think of dogs. But cats can also suffer from food intolerance and food allergies — and these conditions are more common than many realise. Unfortunately, they are often overlooked or misdiagnosed as parasites, environmental allergies, or even behavioural problems.
Food intolerance can be tricky to identify because the signs mimic many other conditions. However, understanding how food-related sensitivities develop, what to look for, and how to test for them is key to helping your cat live a healthier, more comfortable life.
What Does Food Intolerance Look Like in Cats?
Food intolerance in cats can affect both the skin and the digestive system. In fact, gastrointestinal (GI) signs are often the most important clue that a skin condition may be food-related.
Common symptoms include:
Hair loss (alopecia): Often from overgrooming due to itchiness.
Ear infections: Recurrent otitis externa may be linked to food sensitivity.
Excessive grooming and furballs: Cats ingest more hair while licking, leading to fur in stools.
Skin lesions: Such as miliary dermatitis (small, crusted bumps).
Head and neck pruritus: Severe itching of the face, neck, or ears; present in ~42% of food intolerance cases.
Eosinophilic granuloma complex: A group of inflammatory lesions linked to allergic reactions.
Urticaria (hives) and nodules: Raised, itchy swellings.
Plasma cell pododermatitis: Swelling and inflammation of the paw pads.
Use this chart below to determine if your cat’s licking or scratching in normal or if it is excessive and may indicate a medical condition is at play:
Gastrointestinal signs as a key indicator
When skin concerns occur alongside GI issues, food intolerance should be strongly suspected. These can include:
Chronic or intermittent diarrhoea
Inconsistent stool quality
Vomiting (not related to hairballs)
Flatulence or signs of abdominal discomfort
Cats that show both skin and gut problems often improve dramatically on a properly conducted elimination diet, highlighting the close connection between gut and skin health.
Before Suspecting Food Intolerance
Because many of these symptoms overlap with other conditions, a veterinarian will first rule out:
Ectoparasites: Fleas, mites, and lice can cause nearly identical signs. Flea allergy dermatitis is especially common.
Secondary skin infections: Bacterial or yeast overgrowth can worsen itchiness and delay healing.
Behavioural issues: Overgrooming is sometimes attributed to stress, but in many cases the root cause is physical discomfort from food reactions.
Diagnosing Food Intolerance: The Role of Diet Trials
Currently, there is no reliable blood, saliva, or skin test for food intolerance in cats. The gold standard is a strict elimination diet trial.
How diet trials work
Your cat is fed only a novel protein (one they have never eaten before, such as rabbit, venison, or duck) or a hydrolysed protein diet.
All other foods, treats, table scraps, and flavoured medications must be eliminated. Even tiny amounts of the wrong ingredient can cause a flare-up.
The trial usually lasts 6–8 weeks, though some cats may take up to 12 weeks to show improvement.
If symptoms resolve and then return when the old diet is reintroduced, food intolerance is confirmed.
Important considerations
Raw or home-prepared feeding can make diet trials easier because you can strictly control ingredients and avoid hidden fillers or cross-contamination common in processed kibble.
Cross-reactivity: Some proteins are similar. For example, a chicken-sensitive cat may also react to turkey.
Concurrent care: Skin infections and lesions should be treated during the trial to avoid confusion about whether the diet is working.
The Limitations of Hydrolysed Dry Diets
Hydrolysed veterinary diets are widely used for diet trials and can be effective. However, most are produced as dry kibble, which is not ideal for cats in the long term.
Potential drawbacks include:
Low moisture: Cats are adapted to obtain water from their food. Dry diets can contribute to chronic dehydration and urinary tract issues.
High carbohydrate levels: Many hydrolysed kibbles contain starch to hold their shape. Excess carbohydrate can disrupt the gut microbiome, promote dysbiosis, and worsen GI sensitivity.
Lack of diversity: Simplified formulations reduce exposure to multiple nutrients and fibres, which over time can impair microbiome balance.
Ultra-processed: Heavy processing alters food structure, which may affect nutrient bioavailability.
For these reasons, while hydrolysed diets are excellent short-term diagnostic tools, they are not the best choice for long-term feeding. A complete and balanced fresh, cooked, or raw diet (with veterinary or nutritionist oversight) generally aligns more closely with feline biology and supports better hydration, gut health, and overall resilience.
When It’s Not Just Food
If a strict diet trial fails to resolve the problem, other factors should be considered:
Environmental allergies (atopy): Pollens, dust mites, or moulds can cause very similar signs.
Skin barrier weakness: Nutritional support (omega-3 fatty acids, zinc, antioxidants) may help strengthen skin defences.
Chronic stress: Stress can worsen both skin and gut symptoms, creating a feedback loop.
Emerging therapies
CBD oil: Being studied for its anti-inflammatory and calming effects.
Allergen immunotherapy: The only treatment shown to modify the immune system’s long-term response to environmental allergens.
Supporting Cats Through Nutrition
Even if food intolerance is not the sole cause, nutrition plays a vital role in feline health and comfort:
Species-appropriate diet: Cats thrive on high-protein, moisture-rich, low-carbohydrate diets. Raw or gently cooked diets (when properly balanced) can more closely match these needs.
Novel proteins and rotation: Regularly rotating proteins may reduce the risk of intolerance developing over time.
Gut health: Probiotics and prebiotics support a balanced gut microbiome, which is closely tied to skin and immune health.
Skin nutrients: Omega-3 fatty acids (EPA and DHA), zinc, and antioxidant vitamins (A, E) can reduce itchiness and promote healing.
Conclusion
Food intolerance in cats is more common than many owners realise and can show up in many ways — from skin lesions and ear infections to overgrooming and chronic digestive issues. When skin and GI symptoms appear together, food intolerance should be strongly suspected.
A strict elimination diet remains the most reliable diagnostic method, with raw or home-prepared feeding offering unique benefits in precision and control. While hydrolysed diets are helpful tools, they are best reserved for diagnosis rather than lifelong feeding.
By recognising the signs early and working with a veterinarian, cat owners can significantly improve their pet’s comfort, health, and quality of life.
📚 References (with links):
Olivry T, Mueller RS, Prélaud P. Adverse food reactions in dogs and cats: Diagnostic approaches. BMC Vet Res. 2015. https://doi.org/10.1186/s12917-015-0513-4
Bensignor E, et al. Adverse food reactions: Pathogenesis, clinical signs, diagnosis and management. Vet Dermatol. 2018. https://doi.org/10.1111/vde.12580
Hobi S, et al. Cutaneous food allergy in cats: A retrospective study. Jpn J Vet Dermatol. 2013. https://doi.org/10.2736/jjvd.19.7
American Animal Hospital Association (AAHA). Management of Allergic Skin Diseases in Dogs and Cats Toolkit. 2023. https://www.aaha.org/aaha-guidelines/allergic-skin-disease/toolkit/
University of Minnesota Open Veterinary Textbook: Adverse Food Reactions. 2022. https://pressbooks.umn.edu/veterinary-allergy/chapter/adverse-food-reactions/