While your first instinct may be to assume that your dog is suffering from a food allergy, true food allergies aren’t as common as you might think. Confusing food allergies with food sensitivities is a common mistake, not only among dog owners but also among veterinarians.
Food Allergies vs. Sensitivities
True food allergies are much less frequent than food sensitivities and reflect a more immediate immunological response. A classic example of a food allergy is anaphylactic shock, which could occur after ingesting peanuts or being stung by bees. As soon as the person or animal comes in contact with the allergen, their airway closes and they can’t breathe. This response is rapid, as the antigen triggers an immediate and sometimes life-threatening reaction due to hypotension and shock.
A less severe but still serious form of allergic reaction is accompanied by the development of dermatologic signs, such as hives, facial swelling, or itchiness. These can be accompanied by gastrointestinal signs, such as acute vomiting or diarrhea. These signs occur fairly rapidly but less than in the anaphylactic reaction.
Food sensitivity, on the other hand, is usually a chronic condition and often doesn’t involve an immunological response. It’s usually a cumulative response to an offending agent. Although they’re generally not life-threatening, food sensitivities can affect many different aspects of the dog’s physical wellbeing. Common signs of food sensitivity include diarrhea with or without vomiting, poor skin or itchy coat, and chronic ear or foot infections.
Symptoms of Food Allergies in Dogs
We most often associate allergies with sneezing and respiratory problems in people, but in dogs, allergies are most often associated with the skin and gastrointestinal (GI) tract. About 10% to 15% of dogs with food allergies will have both skin and GI signs, and about 20% to 30% of dogs with food allergies will also have itchy skin from other non-food allergies.
GI signs are most often seen as loose stools, with an average of three a day, or vomiting and belching. A skin sign is usually itchiness, and it appears the same as itchiness due to other allergies.
According to one recent study, nearly 8% of dogs presented to a referral dermatology practice had food allergies. This represented about a third of all the dogs presented there with allergic skin disease.
Some people use the phrase “ears and rears” to refer to the characteristic location of itchiness. But it’s typically a bit more widespread than just those regions. In one study, dogs with food allergies suffered from itchy ears in 80% of the cases (and in fact, only the ear was affected in a quarter of all cases); itchy feet in 61%; itchy groin region in 53%; and itchy armpits, anterior foreleg, or eye regions in about 35% of cases.
Secondary ear and skin infections often arise from self-inflicted trauma from scratching and chewing. Along with removing the offending food, you must seek treatment for these infections in your dog.
Does My Dog Have Food Allergies?
Allergies can appear at any age, but most dogs eat an offending food for two years before symptoms appear. Some dogs can develop symptoms as early as two months of eating the offending food. Allergic reactions aren’t something that normally appear immediately after introducing a new food. But once symptoms appear, their onset is often sudden and serious.
Most dogs react to one or two allergens and about 20% react to more. There’s a greater chance that dogs react to animal products from the same species or from related species (cattle, sheep, and deer, for example).
Some breeds, such as Cocker Spaniels, Labrador Retrievers, Golden Retrievers, German Shepherd Dogs, Poodles, and Chinese Shar-Pei, may be at greater risk for food allergies, though they can appear in any breed.
Diet trials are inconvenient and tedious. But compared to your dog’s discomfort, they’re a small price to pay to identify the culprit. Unfortunately, there is no cure for food allergies—except to avoid the offending foods.