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By April 21, 2016 Blog


We have a 7 year old female Lab that is tormented with allergies. She has been treated with several different medications. The only thing that has a lasting effect is a steroid shot (lasts 3-4 weeks). We are afraid of the long term side effects. She has hair loss from scratching. We have enough hair to build another dog. Expensive allergy tests are not an option. We need a second opinion!

Allergy is a general term used to describe when the body’s immune system over-reacts to a certain substance. The role of the immune system is to protect the body against diseases and infection. With allergies the response is exaggerated and can be harmful, causing signs such as those experienced by your Lab.

There are a variety of ways to classify allergies, but I generally group them into three main categories – food, flea and environmental. You do not mention when your dog’s allergies started, if they are year- round or seasonal, or what particular areas are affected. It is important to make at least a mental note of the answers to such questions. Each type of allergy has some “classic” characteristics which can sometimes give us a clue to help narrow down the allergens.

In an allergic reaction to food, antibodies develop to a particular component of the food, usually a protein or complex carbohydrate. Although a food allergy can cause GI disturbances in pets, most often the allergy manifests as skin or ear problems. Food allergies are one of the itchiest conditions that pets can get. In dogs, signs classically include chewing on the feet or limbs, facial or belly itching and ear infections.

Since a dog eats year-round, food allergies are often a year-round problem. The “steroid shot” can temporarily mask the symptoms, but does nothing to address the underlying problem, so the itchiness returns as the injection wears off. Labrador retrievers are probably the number one breed diagnosed with food allergies. In fact, at a recent veterinary conference I attended, the lecturing dermatologist stated that all Labs with allergies have food allergies unless proven otherwise.

A food allergy can only be diagnosed by doing a test known as a food trial. During a food trial, your pet is exclusively fed a special hypoallergenic prescription diet for 8-12 weeks. This diet contains limited ingredients your pet has never been exposed to before. A food trial has a very strict, but simple, protocol. Your pet can have water and the special prescribed diet and nothing else. If the itchiness and other skin problems improve during the food trial, then recur when your pet’s old food is reintroduced, the test is positive for a food allergy.

The second general class of allergies is the flea allergy, known as flea allergy dermatitis, or FAD for short. In a non-allergic dog, a flea bite causes mild localized irritation. A dog with FAD reacts excessively to the saliva in a flea bite with extreme itchiness at the site of the bite. Since fleas often congregate over the tail-base region, the areas that are most often affected include the mid back to the tail base and may extend down the rear limbs. The biting and scratching can be so severe that large amounts of hair are removed.

Just because you do not see fleas on your dog does not mean that FAD is not possible. A single flea bite can trigger a reaction for days. Also, pets may scratch so violently that adult fleas are removed, making them difficult to find.

The best way to address FAD is strict flea control. Due to the mild weather in Southeast Texas, fleas are a year-long problem. Pets can acquire fleas any time they visit an area that has an infestation. Such places may include areas frequented by other dogs or even areas with wildlife, such as raccoons and opossums. In just 30 days, 10 fleas can become an infestation of up to 250,000 adult fleas. Therefore, every pet (dogs, cats, indoors, outdoors) must be on flea preventative all year-round to provide the most complete protection. There are many safe and effective preventatives available from your veterinarian.

The final main category of allergies in dogs is environmental airborne allergies, also known as atopy. Any airborne particle has the potential to cause an allergic response in a dog, but some of the most common outdoor allergens include pollens, grasses, trees, weeds and molds. In next month’s blog we will further explore environmental allergies, including some classic history and exam findings to use as clues, as well as possible therapies that do not involve “steroid shots”.

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