Cause of Flea Allergy Dermatitis

Cause of Flea Allergy Dermatitis
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Flea saliva is the true culprit of flea allergy dermatitis. While all dogs will have a reaction to flea bites, allergic dogs react to flea saliva, too. Learn more to protect your dog here.

Fleas are parasites that subside on the blood of mammals like dogs and cats, though they can live on other host animals as well. They have a life cycle of about six to twelve months, and fully formed adult fleas can survive for long periods without the blood of a host. When an adult flea finds a home on your dog, however, it wonโ€™t likely be fasting.

The fleaโ€™s mouthparts have evolved to penetrate the skin of a dog, especially the thin epidermal area around the abdomen and flanks. When a dog is bitten by a flea for its blood meal, some of the fleaโ€™s saliva is injected through the dogโ€™s skin layer, like backwash. Flea saliva is what causes skin allergy in dogs. The dog reacts to some of the antigenic materials in the saliva, such as amino acids, aromatic compounds, phosphorus, and polypeptides. The dogโ€™s immune system reacts to these materials by producing antibodies.

Once the flea bites an allergic pet, the dog will react in a more pronounced manner than a dog not allergic to fleas would. A small bump and redness may appear, and the bite will be extremely itchy. Even one or two bites will create a constant itching in the dog for days, while a non-allergic dog can be bitten several times until it feels the effect of the flea bite.

Flea allergies may have a genetic component, but these allergies are not predisposed in certain dog breeds or genders. Flea allergies can begin as early as one year in age and generally start when a dog is young. Dogs of any age, however, can develop hypersensitivity to flea saliva, and conditions will worsen with age.

If you discover a flea infestation in your home, recognizing a flea allergy may not be obvious at first since all dogs will react to flea bites to some degree. Your dogโ€™s behavior and a prominent skin condition could indicate a flea allergy is present.

Symptoms of Flea Allergy Dermatitis

When fleas bite a dog for its blood meal, most dogs will show discomfort, itch, and have small red bumps on their skin. Dogs who are hypersensitive to flea bites, however, will have stronger reactions and more pronounced symptoms. Just one or two flea bites spread over one or two weeks can cause severe itchiness in hypersensitive dogs.

Symptoms of flea allergies include:

Skin reactions

Flea allergies cause pruritis or severe itching of the skin. Reaction to the flea saliva may manifest as redness, pimple-like bumps, pus-filled bumps, or scabs. In severe cases, dogs may have hair loss and skin rash. Hotspots, or painful red, circular sores that often ooze, may appear on a dogโ€™s backside or tail base. Typically, a dogโ€™s hind body is most affected by flea allergy, though lesions can appear anywhere. Check thoroughly around your dogโ€™s lower back, tail, neck, and back of legs for skin reactions.

Constant itching

Dogs with pruritis will frequently itch and scratch their bodies. This behavior will exacerbate the symptoms and could lead to secondary bacterial infection. Dogs may also chew, lick, or bite their tails, legs, and behinds. While some itching is normal, be on the lookout for excessive itching accompanied by skin damage. Dogs with hypersensitivity to flea saliva also tend to groom and lick their hair obsessively.

Evidence of fleas

If you notice evidence of flea dirt or signs that your dog has fleas, then flea allergy is a strong possibility for your dogโ€™s skin condition. Even after an outbreak of fleas has been eradicated, evidence of flea bite allergy will pop up if just a few fleas remain. In fact, most dogs with flea allergies have very few fleas on their body because they groom more.

Recurrent tapeworm

Dogs that ingest fleas from biting and chewing their irritated skin will be more prone to getting tapeworm. Fleas are common hosts of tapeworm larvae, and when a dog ingests the parasites, the tapeworm eggs are released and spread to the dogโ€™s small intestine. This is an unfortunate side effect of some flea infestations, though ingesting fleas does not indicate that a dog is definitely allergic to flea bites. Since dogs with flea allergies groom more, however, they are more likely to ingest fleas and tapeworm larvae.

Because Flea Allergy Dermatitis causes a cycle of scratching and itching, your dog cannot heal alone. Once you recognize the symptoms, it's important to pursue treatment to keep your dog from the discomfort of Flea Allergy Dermatitis.

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis, or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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Flea Allergy Dermatitis

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