How do I know if my cat has a food allergy?

Food allergies in cats are less common than many owners believe, but they are real and can cause significant discomfort. The tricky part is that the symptoms often overlap with environmental allergies and other skin or digestive conditions — making accurate diagnosis a challenge.

True food allergy vs. food intolerance

A food allergy is an immune-mediated reaction to a specific protein, producing consistent symptoms each time that protein is eaten. It does not improve with antihistamines and is non-seasonal.

A food intolerance is a non-immune digestive reaction (similar to lactose intolerance in humans) causing GI symptoms like vomiting or diarrhoea.

Most common allergens in cats

1. Fish (particularly tuna and seafood blends) — the most commonly implicated
2. Beef
3. Dairy (milk, cheese, yoghurt given as treats)
4. Chicken
5. Wheat and other grains (less common than in dogs)

Note: cats typically develop allergies to proteins they have been exposed to repeatedly over time, not to new proteins.

Symptoms to watch for

- Skin symptoms — non-seasonal, intense itching especially around the face, neck, ears, and abdomen; miliary dermatitis (tiny crusty bumps); symmetrical hair loss; over-grooming
- GI symptoms — intermittent vomiting (especially undigested food, not hairballs), loose stools, increased frequency of defecation
- Ear symptoms — recurrent ear infections (otitis), often with dark waxy discharge

The elimination diet trial

As with dogs, the only reliable method to diagnose a food allergy in cats is an 8–12 week elimination diet trial with a novel protein (one the cat has never eaten) and a novel carbohydrate, or a hydrolysed protein diet. During this period:

- No treats, flavoured medications, or table scraps
- Flavoured dental chews must also be stopped
- All family members must comply

Flovvi tip

Create a symptom log in Flovvi before starting the elimination trial — noting itching frequency, vomiting episodes, and stool consistency. This baseline makes it much easier to objectively assess whether the trial diet is helping.