Food allergies

Our guide has been authored by qualified veterinarians, but should not be taken as substitute for medical advice or professional veterinary consultation. If your pet displays any unusual symptoms, we strongly advise seeking guidance from a veterinarian

Understanding Food allergies in dogs and cats

Food allergies are an overreaction of the immune system to specific food components, often leading to skin and/or gastrointestinal symptoms. Cats and dogs with food allergies often suffer from additional allergies, such as flea bites and environmental allergens. Food allergies can appear at any age, even to a food component your pet has been exposed to repeatedly previously. Symptoms range from very mild, such as occasional itches or soft stool, to severe reactions that require emergency treatment.

Danny's story

When Danny, a mixed Siamese cat, was 18 months old, her owner noticed she was excessively grooming herself, causing several bald patches. She was also vomiting up hair and food and losing weight. The vet examined Danny and conducted several skin tests, which came back negative. Before trying more complex tests under anesthesia, her owner tried a food trial using a special veterinary diet to help rule out food allergies. Danny started her new diet, and the family was instructed to refrain from offering any other foods. Fur started growing back within less than a month, and Danny stopped scratching, licking, and vomiting. After the old food was reintroduced, Danny began licking her fur again, confirming the diagnosis of a food allergy.

Food allergies's Causes: Uncovering Triggers

Like other allergies, the immune system’s overreaction causing food allergies is likely the result of genetics combined with environmental exposure. The immune system flags these food components as foreign substances that need to be eliminated. Food allergies often appear alongside other allergies for this reason, which is why many pets who show sensitivity to food components also show sensitivity to fleas or other environmental allergens.

Recognizing Food allergies: Signs and Symptoms

Excessive itching: affecting mainly the head and the sides of the body
Chewing near the rear and on the limbs (“cobbing”)
Recurrent ear infections
Excessive licking of the anus
Excessive paw licking
Over-grooming: this causes bald patches
Small sores and bald spots: these are caused by the self-grooming
Facial swelling
Irritation and redness around the eyes and nose
Frequent and/or soft stools
Watery-to-bloody diarrhea
Vomiting after eating
Excessive gas

As you can see, there are skin-related symptoms and digestive ones. Anaphylactic shock is also possible, but extremely rare when it comes to food allergies.

Food allergies Diagnosis: How it's Identified

The above skin and digestive symptoms may initially suggest a food allergy, but most patients will have only a few of these and may have only skin or only digestive symptoms. This speaks to the importance of keeping food allergies on the radar with any of the above symptoms. Environmental allergies cause similar itch patterns, although food allergies usually cause a nonseasonal itch compared to the seasonal flaring typical of most environmental allergies.

The only way to be sure when diagnosing a food allergy in cats and dogs is a strict elimination diet trial. The pet eats only food containing a protein they’ve never been exposed to (novel protein) or a special veterinary food that doesn’t trigger an allergic reaction (hydrolyzed protein). Then, if symptoms improve, the previous food is reintroduced. If symptoms quickly return, the diagnosis is confirmed. It’s important to note that blood tests and skin tests do not diagnose food allergies.

Treating Food allergies: Options and Approaches

The ideal treatment is avoiding the food causing the reaction.

Anti-itch medications are often given in cases involving additional allergies in which dietary change alone is insufficient.
At initial diagnosis, if there are any secondary infections present, these will need to be treated with antibiotics or antifungals.
Gastroprotectants and probiotic supplements can help treat digestive symptoms.
In cases involving acute reactions that result in swelling, antihistamines can be administered by injection or orally.
In extremely rare cases of anaphylactic shock, your dog will need to go to the emergency clinic for life-saving adrenaline injections and urgent fluids.

Food allergies: Surprising Facts

Contrary to popular belief, chicken is not more allergenic compared to other proteins. We often think that because it’s a more common protein in pet food. Studies show that beef in dogs and fish in cats (yes, really!) are equally, if not more, allergenic.

Food allergies are actually not very common. Environmental and flea allergies are much more common in both cats and dogs.

90% of the time, the allergic reaction is caused by a protein. Only in a few cases does it stem from carbohydrates or dairy.

Vet's Tip: Dealing with Food allergies

If we suspect a pet suffers from a food allergy, conducting a food trial is crucial. An elimination diet trial serves as a diagnostic tool used to confirm or rule out an allergy rather than treat it. During the trial, owners must only offer the test diet for 8 straight weeks. Even a small treat or a piece of food dropped at dinner can compromise the results.

Price Tag

Veterinary consultation

$60-$120

Prescription hydrolyzed protein diet

$40-$130 per bag

Latest in Research and Treatments

Until recently, a food trial would last up to 12 weeks, during which no anti-itch medications were provided, which was challenging and frustrating, causing significant discomfort to the pet and its loving owners. Fortunately, recent protocol changes allow the use of anti-itch medications for a limited time during the trial, offering significant relief to animals with intense itching and sometimes shortening the trial period and improving overall outcomes. Currently, food trials are recommended for a period of 8 weeks.