Canine Flea Allergy

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.

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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. However, when an adult flea finds a home on your dog, it won’t likely be fasting.

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

Once the flea bites an allergic pet, the dog will react more pronouncedly 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 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 of 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 dog’s behavior and prominent skin condition could indicate a flea allergy is present.

Symptoms of Flea Allergy Dermatitis

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When fleas bite a dog for its blood meal, most dogs will show discomfort, itch, and have small red bumps on their skin. However, dogs who are hypersensitive to flea bites 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 dog’s backside or tail base. Typically, a dog’s hind body is most affected by flea allergy, though lesions can appear anywhere. Check thoroughly around your dog’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 dog’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 tapeworms. Fleas are common hosts of tapeworm larvae, and when a dog ingests the parasites, the tapeworm eggs are released and spread to the dog’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, 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.

Frequently Asked Questions

How do you stop flea allergy dermatitis in dogs?

Flea allergy dermatitis (FAD) is a common allergic skin disease in dogs caused by an allergic reaction to the saliva of fleas. Use flea preventatives year-round to kill and prevent fleas from biting your dog. These can include topical or oral medications prescribed by your veterinarian. Regular grooming can help you detect fleas early before they become a problem. Use a flea comb to remove fleas and their eggs from your dog's coat. Vacuuming your home frequently can help remove fleas and their eggs from your carpets and furniture. Treat your home with a flea control product to kill fleas and their eggs. Be sure to follow the instructions carefully and keep your dog away from treated areas until the product has dried. Some dogs may benefit from a hypoallergenic diet to help manage their FAD symptoms. If your dog is already suffering from FAD, your veterinarian may recommend additional treatments to help manage their symptoms, including medications to relieve itching and inflammation, topical creams or sprays to soothe the skin, and antibiotics to prevent or treat secondary infections.

How long does flea allergy dermatitis take to heal?

The time it takes for flea allergy dermatitis (FAD) to heal in dogs can vary depending on the severity of the allergy and how quickly it is treated. In some cases, FAD can start to improve within a few days of starting treatment, but it may take several weeks or even months for the skin to heal fully. The itching usually takes about 1-2 weeks to subside. It is necessary to note that even if the skin appears to have healed, it is still important to continue flea prevention and control to prevent a recurrence of FAD. Dogs with a history of FAD are more prone to developing the condition again, so it is important to maintain regular flea prevention and monitoring to prevent a recurrence.

What is a home remedy for flea dermatitis?

While there are many home remedies for flea dermatitis, it is important to note that they should be used with caution and only under the guidance of a veterinarian. A bath with colloidal oatmeal can help soothe irritated skin and reduce itching. Follow the package instructions for the correct ratio of oatmeal to the water. A diluted apple cider vinegar rinse can help soothe the skin and reduce inflammation. Mix one part apple cider vinegar with one part water and apply it to your dog's coat after shampooing. Rinse thoroughly. Coconut oil can help moisturize the skin and reduce itching. Apply a small amount of coconut oil to your dog's coat and gently massage it in. Soaking your dog's paws in a warm Epsom salt solution can help reduce itching and inflammation. Mix 1 cup of Epsom salt with 1 gallon of warm water and soak your dog's paws for 5-10 minutes.

What medication is used for flea allergy dermatitis?

The medication used to treat flea allergy dermatitis (FAD) in dogs can vary depending on the severity of the allergy and the presence of secondary infections. One of the most important steps in treating FAD is to prevent flea infestations. Your veterinarian may prescribe a flea-preventative medication such as a topical or oral medication. These include topical medications such as fipronil (Frontline), imidacloprid (Advantage), and selamectin (Revolution), as well as oral medications such as spinosad (Comfortis) and afoxolaner (NexGard). Anti-itch medication such as corticosteroids or antihistamines may be used to relieve itching and inflammation. These include corticosteroids such as prednisone or dexamethasone, as well as antihistamines such as diphenhydramine (Benadryl) or cetirizine (Zyrtec). If there is a secondary bacterial infection, your veterinarian may prescribe antibiotics to treat the infection. These may include medications such as cephalexin, amoxicillin-clavulanic acid, or enrofloxacin, depending on the type of infection. Your veterinarian may recommend a topical cream or spray to soothe the skin and reduce inflammation. These may include medications such as hydrocortisone cream or spray, triamcinolone acetonide cream or spray, or miconazole/chlorhexidine spray. In some cases, your veterinarian may recommend immunotherapy, which involves giving your dog small amounts of the allergen over time to help desensitize them to the allergen. Immunotherapy for FAD in dogs involves using a medication called allergen-specific immunotherapy (ASIT), which is also known as allergy shots. Some common ASIT options include sublingual immunotherapy (SLIT) or subcutaneous immunotherapy (SCIT).

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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