Have you ever had an itch you couldn’t reach? Maybe it was in the center of your back, just beyond your fingertips. It’s enough to drive you crazy, right? You’ll do anything to get relief, including looking silly as you act like a contortionist trying to reach that one spot. Suddenly, relief from the itch is your number one priority.
Now, imagine for a moment you were finally able to reach the itch, only to find that the more you scratched it the more it itched. You now have an idea what it’s like for many of our pets with skin allergies.
Skin allergies afflict thousands of pets every year. According to Dr. Richard Anderson, staff dermatologist at Angell Memorial Animal Hospital, skin allergies are a significant problem with pets. “Up to 10-15 percent of the dog population and maybe the cat population suffer from some form of allergy, be it fleas, food or inhalants.”
Dr. Robert M. Schwartzman, professor of dermatology as the School of Veterinary Medicine at the University of Pennsylvania, points out that the four most common forms of skin allergies in
dogs are: flea bite hypersensitivity, inhalant allergies, food allergies, and contact allergies. Cats suffer from these same problems with flea bite allergies being the most common followed by food allergies, inhalant allergies, and contact allergies.
Flea bite allergies (FBA), far and away the most common, result in a very itchy condition which is worsened by the self-mutilation caused by the pet’s constant scratching at the irritated areas. In dog’s these areas include the lower back, thighs, and groins. In cats, flea bite hypersensitization results in small crusty sores, usually along the entire body.
Since flea bite allergy is caused by the pet’s immune system reacting to the protein injected into the skin from a flea bite, the duration of the problem depends on the flea season. Pets which live in the north often will have a period of relief during the winter months while their southern counterparts must do battle year round. Once a pet becomes hypersensitive to flea bites, it may take only one bite to set the pet to itching over its entire body. This explains why some pets may be covered with fleas with little or no affect why another pet may break out in uncontrollable scratching at the first sign of a flea.
Presently, curing FBA through desensitization has met with limited success. The best approach to managing the condition is rigorous flea control and treating the allergic reaction with cortisone and antihistamines.
Flea control must go beyond simply treating the fleas which are found on the pet. “Just treating the animal,” says Dr. Schwartzman, “doesn’t solve the problem. You must treat both the animal and the environment”
Fleas lay hundreds of eggs while they are off the pet in the house and yard where the pet resides. If you aren’t treating these areas as well as the pet, you’re missing the bulk of the problem. Says Dr. Anderson, “It’s more important to treat the environment than the animal to avoid the use of a lot of insecticides on the animal.”
With any flea preparation, READ THE LABEL AND FOLLOW THE INSTRUCTIONS CAREFULLY! Far too many pet owners have poisoned their pets from the misuse of flea control products.
Some relief from fleas may be on the horizon with a new oral medication which is administered to the pet. When the flea bites the animal, it will also ingest a small amount of the medication, which then acts like a birth control pill, preventing egg and larval stages of the flea from developing.
In inhalant allergies (also known as atopy), pets become allergic to foreign material which they inhale in the normal course of the day, including grass and tree pollen, molds, animal dander, dust, etc. “Atopy is an inherited disease,” says Dr. Anderson. “Just as in people who have asthma, it often runs in families. Whereas FBA normally occurs in older pets, atopy is most commonly seen in dogs and cats one to four years of age.
Atopic dogs usually rub their face, lick their feet and under their front legs which causes the areas to become inflamed, opening the skin up to secondary bacterial infections. The breeds in which inhalant allergy is most common are terriers, Dalmatians, Golden retrievers and Poodles. The allergy may or may not be seasonal depending on what the pet is allergic to.
The age of onset of inhalant allergy in cats varies and may occur in any breed. Atopic cats are best known for licking or pulling out their hair. Some of them will have sores and scales where the irritation is worse.
Diagnosing inhalant allergies is a combination of obtaining a thorough history such as the problem being reported in the pet’s parents, coupled with the physical exam which reveals the typical distribution of lesions. Confirmation may be done with a blood test which measures the level of antibodies produced by the body in response to various allergens (allergy-producing agents) found in the surroundings as well as with the more traditional patch test. In the patch test, minute amounts of the suspected allergens are injected under the pet’s skin. The resulting skin reaction is measured to determine which allergens the pet is allergic to.
Although the ideal way to treat atopy is to remove the allergen from the pet’s environment, this often isn’t possible. Over the short term, medical treatment with cortisone or antihistamines will provide relief but long term resolution depends on desensitization. According to Dr. Schwartzman a desensitization program is effective in about 50 percent of the cases.
With food allergies, Dr. Anderson points out that it’s important to differentiate allergies from food intolerance. “If (your pet) has an allergy to a food it oftentimes isn’t a new food that’s been introduced to the diet. It’s something that’s been eaten for a period of time. If it’s an intolerance, it’s more likely you can do something about it.”
Since the body’s immune response is the same in food allergies as in inhalant allergies, the signs of food allergies may be impossible to differentiate from inhalant allergies. One general difference is that food allergies may occur at any stage of life. Often the head and tips of the ears are affected. The other major difference is that food allergies are not seasonal whereas inhalant allergies often are.
Although there are blood and skin tests for food allergies, most veterinarians agree they are not accurate enough to depend upon. Therefore, the most common way to diagnose a food allergy is with a restricted diet. This can be a difficult task since pets can be allergic to many different food substances and they may need to stay on the diet for a month or more before being able to confirm the diagnosis.
Since the most common class of food which causes an allergic response is protein, hypoallergenic diets often contain such ingredients as lamb and rice, chicken and rice, lamb, and potatoes or in dogs, vegetarian diets. (Vegetarian diets aren’t possible in cats since they need to be fed meat.) Once a food allergy is diagnosed in this manner, the “diagnostic diet” is then expanded to include everything needed for a balanced diet.
Contact allergies are much more common in people than in pets and can easily be confused with simple irritant reactions which do not have an allergic component. Common contact allergies in people include poison ivy, chemical reactions commonly found in the workplace, and reactions to certain soaps.
Poison ivy is rare in domestic animals. The most common causes of contact allergies in dogs are from reactions to topical drugs such as ointments which contain neomycin, also rug shampoos, floor cleaners, dyes used in carpeting, deck stains and possibly from certain plants.
Cats, on the other hand, rarely have problems with contact allergies, more often experiencing an irritant reaction without an allergic response.
Two things are necessary for an animal to develop a contact allergy: a high genetic predisposition (as is the case with man and guinea pigs), and prolonged intimate contact with the particular agent. Dogs and cats are well protected from such contact by their fur which acts as a guard. For this reason, most cases of contact allergies occur on the areas of the body with the least amount of fur.
Since good diagnostic tests are unavailable for contact allergies, diagnosis is through the history and physical exam. Contact allergies can occur at any age and at any time of the year. An important finding which differentiates it from other allergies is that the lesions are usually confined only to the hairless areas of the body, especially on the scrotal skin, armpits, webs of the feet, and belly.
The challenge of the veterinarian is not only to differentiate the various skin allergies from each other but also from a wide array of other skin disorders which may look very similar. Whereas the skin responds to a problem in a limited number of ways, i.e. redness, pustules, scabs, the number of things which can cause the skin to react is much larger.
Skin allergies must be differentiated from primary bacterial infections, which can be difficult since secondary bacterial infections are not uncommon complications of many allergies. Also, certain cases of scabies (sarcoptic mange) may look like a generalized allergic reaction.
Occasionally, hormonal problems which affect the skin can be confused with an allergy. Hormonal skin disorders aren’t normally pruritic (itchy), but they can become very irritating if a secondary bacterial infection occurs on top of the hormone imbalance. As Dr. Anderson points out, “Everything that is itchy or inflamed is not necessarily an allergy.”
The other side of the coin is, allergies don’t always affect the skin. Says Dr. Anderson, “If you see dogs with inhalant allergies, they may have signs somewhat like people: conjunctivitis, sneezing, or respiratory signs – bronchitis, chronic cough.” Food allergies may also affect the gastrointestinal system, leading to diarrhea and/or vomiting.
Skin allergies can be some of the most difficult and challenging conditions for the pet, vet and pet owner. Due to their chronic nature and the fact that many forms of skin allergies cannot be cured but only controlled, close attention is important. Working closely together, you and your veterinarian can provide relief from these uncomfortable and potentially dangerous conditions. Remember, no one likes to have an itch they can’t relieve. The same is true for our pets.
THE END
