When I applied to veterinary school, no one told me I would spend a good portion of my day smelling ears. Nonetheless, it’s true — veterinarians can sniff out the whiff of yeast or infectious ooze the way a wine steward can sniff out a vintage cabernet. Between stinky ears, itchy skin and bald rear ends, you’ve just about filled out three-quarters of my day’s appointments.
Over time, as I learned more about the big picture and pursued my interest in dermatology, I finally learned that these very common problems in juvenile dogs share a common underlying theme: dog allergies.
Canine allergies generally fall into one of three categories: flea, food or environment. Which one your pet is most likely to have depends on your dog’s genetics, age and environment. If he’s really unlucky, he may even have more than one type of dog allergy.
No matter the cause, the most common sign owners notice is itchy or reddened skin, with or without hair loss. The itching may be confined to one part of the body, such as the face or feet, or may be generalized. Unlike in people, respiratory signs such as bronchitis or rhinitis (runny nose) are far less common. When I see a young dog with unstoppable itching, I assume we have an allergy workup on our hands until proven otherwise.
Dog Allergies From The Environment
Up to 10 percent of dogs may suffer from environmental allergies, known as atopy, over their life. While the age of onset varies from about 6 months to 6 years of age, dogs age 1 to 3 years old are most likely to develop signs of atopy for the first time. Depending on the specific nature of the dog’s allergies, the symptoms may be seasonal (for something like a grass allergy) or year-round (as is often seen in dust mite allergies.)
Skin testing or blood tests may be used to help determine what allergens a young dog is allergic to, but most clinicians diagnose atopy based on the dog’s history and the physical exam. It can take weeks or months to determine the ideal course of therapy for an atopic dog, which may include allergy shots, immunosuppressants, antihistamines, essential fatty acid supplements and bathing. A newer drug, Apoquel, is expected to be widely available in the next year and shows great promise in treating dogs over 12 months of age.
The treatment process can be frustrating for owners, as it often takes a bit of trial and error to determine what type of therapy a pet will need. While antihistamines are the least expensive treatment and have the least serious side effects, they are also the least effective: only 20 percent of atopic dogs are controlled on antihistamines alone. With the more aggressive forms of treatment, such as allergy shots or the medicine cyclosporine, we see closer to a 75 percent response. Treatment is lifelong, as dogs do not grow out of these allergies.
Dog Allergies From Food
Food allergies also occur in dogs, though less commonly than atopy or flea allergies in this age group. From outward appearances, a food allergic and an environmentally allergic dog are indistinguishable — both can have localized or general itching and hair loss, reddened skin and splotchy rashes. Recurrent ear infections are also common and may be the only sign of the allergy. In vet school, we learned “face and feet” are the most common regions for a food allergic dog to itch, but it can happen anywhere on the body.
The only reliable way to diagnose a food allergy is through an elimination diet: that means 10 to 12 weeks where the dog eats nothing but a hypoallergenic diet containing a single protein and a single carbohydrate, neither of which the dog has had before. Most of these diets have very unusual makeups, such as kangaroo and oats or rabbit and peas, as they need to contain ingredients that the dog has never been exposed to.
If the pet responds to the diet, he can be challenged with one new food a week to determine exactly what he is allergic to. Most of the time, a protein is the offending source: chicken, beef and dairy, though carbohydrates or preservatives may also be a culprit. Blood tests, although available in some clinics, are not considered reliable ways to diagnose food allergies.
Dog Allergies From Fleas
Last but not least, we have the lowly flea to blame for some dogs’ misery. While most dogs are irritated by fleabites, a dog with a true hypersensitivity can have a tremendous reaction to a single fleabite. Many of these dogs are particularly itchy in the hindquarters: at the tail base and the back of the thighs. Modern medicine has revolutionized the quality of life for these pooches; no fleas, no problem. Dogs with flea allergies should be kept on flea control religiously.
It’s hard to overestimate just how miserable these dogs can get when their allergies are uncontrolled. It may not be easy, but man’s best friend deserves help when dog allergies rear their ugly head.