The other day a copy of the FDA Consumer Magazine ended up on my desk. In it I found an article written by Linda Bren, content of which I wanted to share on this blog because in my opinion it is an easy to understand basic introduction to one of the most common problems seen affecting our pets these days: Allergies. Linda wrote:
“When your dog pumps its leg frantically to scratch its ear, or your cat bites its tail furiously until the fur falls out, it's clear that your pet is itching for relief. Occasional scratching is normal, but if a pet scratches or bites itself relentlessly, a health problem may be the cause. Itching can be triggered by a variety of conditions, ranging from liver disease to lice, from fungus to fleas, from mange to anxiety.”
According to Linda Messinger, D.V.M. and board-certified veterinary dermatologist at the Veterinary Referral Center of Colorado in Englewood the leading cause of itching and scratching in pets is allergies. Allergies are also the most common underlying cause of ear problems in dogs," she adds.
Unlike people with allergies, animals don't usually get stuffy or runny noses or watery eyes. Their main symptom is itchy skin, which can turn raw and red from scratching, licking, and chewing. This condition is called allergic skin disease, or allergic dermatitis. With enough scratching and biting, open sores can form, creating a haven for bacteria or yeast that can lead to infection.
"Just about every mammal can get allergies," says Lisa Troutman, D.V.M., a veterinarian with the Food and Drug Administration. "So can hamsters, rabbits, birds, and some other pets." But dogs and cats are the pets most frequently seen with allergies.
To relieve the itch, dogs may scratch and bite at themselves and rub their face with their paws or against the floor and furniture. "Cats tend to pull out their hair and get patchy hair loss on their ears, legs, and around their eyes," says Troutman. "They'll make themselves bald."
There is no cure for allergies. "They are a lifelong problem," says Messinger, "and often times they get worse as a pet gets older."
But there are treatments to relieve itchiness, clear up infections that arise from constant scratching, and even "desensitize" a pet to substances that cause allergies. In addition to regulating drugs for people, the FDA regulates drugs for animals, and the agency's Center for Veterinary Medicine has approved medications to treat itchy pets and their infections.
The key to making your pet comfortable is to find out the cause of the itchiness. If the pet is allergic, determining the source of the allergies will help with treatment, says Messinger.
There are different types of allergies and the ones that can plague pets are grouped into four types: flea, food, atopic, and contact.
The most common type of allergy in both dogs and cats is flea allergy. The offending allergen is actually the protein in flea saliva left in the skin after a fleabite.
Atopic, or inhalant, allergy is the second most common allergy in dogs and the third most common in cats. Breathing in or directly contacting air borne particles in the environment, such as mold spores, dust, tobacco smoke and pollens, will activate atopic allergies.
If a pet is allergic to pollens, it will show symptoms even if you keep it indoors, says James Jeffers, V.M.D., a board certified veterinary dermatologist at the Animal Allergy and Dermatology Clinic in Gaithersburg, MD. Outside airborne substances waft their way into the house, and air filters don't tend to bring relief to pets with these types of allergies, he says.
Although pets with atopic allergies sometimes have respiratory problems, such as coughing and sneezing, they more typically develop itchy skin. Certain dog breeds are more likely to develop atopic allergies, including Terriers, Dalmatians, and Golden and Labrador Retrievers.
Food allergies are the second most common type of allergy in cats and the third most common in dogs. Food ingredients most likely to trigger allergies in cats are fish, milk, beef, and eggs. Ingredients most likely to cause a reaction in dogs are beef, soy, chicken, milk, corn, wheat, and eggs. Some pets with food allergies may have vomiting and diarrhea.
A reaction to physically touching a substance is called contact allergy, the least common type of allergy in dogs and cats. Contact allergens include grass, wool, and plastic. Jeffers occasionally sees dogs in his clinic with "plastic dish dermatitis," an irritation to the skin on the nose caused by a reaction to an antioxidant found in a plastic food or water dish. The condition clears up when the pet is switched to a metal or ceramic dish. And although uncommon, some cats become allergic to kitty litter, says Jeffers. But allergies caused by contact with chemicals, such as those contained in cleaning fluids, waxes, carpet cleaners, and lawn fertilizers, are "about 1 in a million," he says. Nevertheless, these products are potentially toxic, and pets should be restricted temporarily from areas treated with them.
Some pets' allergies are set off by seasonal changes. Springtime, with its tree pollens, brings on the animal form of hay fever, which is primarily itchy skin. Mosquitoes and flies, which may trigger allergies, are rampant in summer. Grasses and flowers often release pollen in summer and late blooming plants produce pollen in early fall, creating airborne irritants. Fleas and the allergies they activate persist in spring through fall in most parts of the country, but are found year round in some areas.
Geography also plays a role in allergic reactions. Regional changes mean different varieties of grasses, trees, insects, and other environmental elements, which can affect allergies. Jeffers says when he took his dog camping in Maine, the pup was healthy, but when he brought him back home to Maryland, he started itching.
Pets, like people, have allergic responses when their immune system overreacts to certain substances. When they enter the body, the offending substances, called antigens or allergens, set off an alarm. This alarm stimulates the body to produce antibodies to defend itself against what it perceives as a threat, the allergen invaders. The antibodies attach themselves to immune cells, called "mast cells," within the skin and other body tissues. When the allergens penetrate these tissues' surfaces, they are captured by the antibodies, which then stimulate the mast cells to release powerful chemicals into the surrounding tissues. It is these chemicals, called histamines, that cause inflammation and itching.
The body's immune system is meant to protect against harmful substances, so why do some animals have a severe reaction to non-threatening substances? "We think it's very similar to the situation in human beings," says Daniel O. Morris, D.V.M., a board certified veterinary dermatologist and chief of staff of the veterinary hospital at the University of Pennsylvania in Philadelphia. Some animals, like some individuals, "may carry genes that put them at risk for developing allergic reactions," he says.
Another explanation is the hygiene theory, says Morris, which suggests that if you allow children to be exposed to infectious organisms early in life, their immune response may better control infections and make them less likely to develop allergies. In societies that stress cleanliness and try to protect children from dirt and disease, a child's body may overreact when confronted with a foreign substance, even a harmless one. The hygiene theory may explain why allergies in children are on the rise in the developed world, and the same explanation could apply to allergies in pets, says Morris.
There are many conditions that can make a pet itch or have hair loss, including endocrine, autoimmune, infectious, and parasitic skin diseases. It takes some detective work to identify the cause. A veterinarian may be able to diagnose the problem or may refer your pet to a veterinary dermatologist, a specialist in treating skin conditions in animals.
If allergies are suspected, the first thing a veterinarian will usually ask is if the pet is on a flea control product, says Troutman. Flea allergies are the most common type of allergies and the easiest to control, she says. And just because a pet is kept indoors doesn't mean it can't have fleas. An owner might bring fleas into the house on a piece of clothing, and the fleas can jump onto the pet. Just a single flea bite can cause an allergic animal to itch severely for more than five days, according to the American Animal Hospital Association.
Pet owners have many options for flea control on pets and in their environment. Veterinarians can recommend an appropriate product.
Once flea allergies are ruled out and if the itch is non seasonal, food allergies are checked next. Stay tuned for part 2 on this topic when we address those and also look at allergy testing and treatments
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