What is the difference between food allergies and food intolerance (adverse food reactions) in cats?
Traditionally, the terms "food allergy" and "food intolerance" have been used to describe all adverse food reactions in cats.
Food intolerance is the most accurate term for adverse food reactions in cats. Food intolerance covers a large number of adverse food reactions that do not involve the immune system, and generally cause digestive issues.
The term food allergy or food sensitivity is most accurately applied when the immune system reacts to an allergen (a component of the food that creates signs and symptoms). The allergen is a protein or multiple proteins, and immune system reactions to these proteins generally require several exposures before signs are evident.
Food intolerance in cats often looks like food allergies, because there are only so many ways that the body can demonstrate a problem with food. One characteristic of food intolerance is that it occurs on the initial exposure to a food or food additive. The incidence of food intolerance versus food allergy is not known.
What kinds of adverse food reactions happen in cats?
There are several categories of food reactions that may occur in cats:
Food Poisoning. Food poisoning is an adverse reaction caused by the direct action of a food on the cat. Food poisoning is not as common in cats as it is in dogs, as cats don’t tend to eat things they shouldn’t. However, cats are not immune to this problem. Food poisoning may occur due to any of the following causes:
- Ingesting excessive amounts of a specific nutrient like vitamin A, iron, or calcium
- Scavenging spoiled food
- Ingesting specific problematic foods, such as caffeine, alcohol, onion, raw eggs, or raw meat
- Ingesting plants that cause gastrointestinal irritation, such as lilies, tulips, and aloe vera
Reactions to food additives. Adverse reactions to food additives are frequently reported in people, including reactions to compounds like sulfites, monosodium glutamate, and spices. Despite the impression that food additives can cause problems in cats, evidence to support this suggestion is lacking. However, disulfide is one food additive that can cause problems. Disulfides are found in onions and can cause damage to red blood cells.
Reactions to certain carbohydrates. There are several important carbohydrate intolerance disorders in humans. Recognized carbohydrate intolerance in cats is less frequent, but a common carbohydrate reaction in cats is lactose intolerance. Signs of lactose intolerance include diarrhea, vomiting, bloating, and abdominal discomfort after ingesting cow's or goat's milk.
Dietary indiscretion. Dietary indiscretion is far more common in dogs than in cats, but cats also sometimes eat things they should not eat. Gastrointestinal signs may result from bacterial contamination, fat or grease, or from bones.
How do I know if my cat has a food allergy or food intolerance?
The best way to determine whether your cat is experiencing a food allergy/sensitivity or dietary intolerance is to start by providing your veterinarian with a detailed diet history, including everything your cat currently eats, has eaten in the past, or may have access to on a typical day. This information can help identify potential triggers for your cat’s symptoms.
It’s important to distinguish between an adverse food reaction and an immune-mediated food allergy or sensitivity, as the latter often results in recurring skin or gastrointestinal signs that require a more comprehensive management approach. Keeping track of your cat's feeding schedule, nutrient profile, and the timing and severity of any symptoms will help your veterinarian make a clearer diagnosis and guide the most effective treatment plan.
