What is flea allergy dermatitis?
Flea allergy dermatitis (FAD) is a skin condition caused by an allergic reaction to the proteins in flea saliva. In an allergic reaction, the body’s immune system overreacts or is hypersensitive to a substance (antigen) that is usually harmless.
FAD is a common cause of itching in dogs. When a flea bites a dog to consume a blood meal, some of its saliva is injected into the skin. The antigens in the saliva cause an intensely itchy response in sensitive dogs.
Dogs with FAD do not have to be infested with fleas to be itchy: a single flea bite can cause itching for several days. Fleas typically only stay on the dog for the minutes to hours they feed, which is why you do not often see live fleas on your dog unless there is a severe flea infestation in their immediate environment.
Are only certain dogs allergic to fleas?
FAD can develop at any age. Dogs with other types of allergies, such as environmental allergies (e.g., pollen, molds, dust mites) tend to be highly sensitive to flea bites and are much more susceptible to FAD than other dogs.
What are the clinical signs of FAD?
Signs of FAD include:
- Itching and hair loss anywhere on the body but most frequently seen from the middle of the back to the tail base and down the rear legs (the flea triangle)
- Ear infections
- Scabs, sores, or skin infections due to scratching
How is FAD diagnosed?
Clinical signs often indicate that your pet suffers from FAD. Intradermal allergy tests (skin tests like those performed in humans) or specialized blood tests (IgE blood tests) can confirm flea allergy in your dog. The signs of FAD are often classic, and dogs respond to treatment so quickly that formal allergy testing is only necessary in some cases.
How is FAD treated?
Strict flea control is essential in treating FAD, because the injection of flea saliva causes an allergic response. Even if you do not see fleas on your dog, it is important to continue rigorous flea treatment and maintain environmental control. Most flea infestations occur in warmer weather but can happen year-round. The best treatment is flea prevention, using modern oral or topical medications. Speak to your veterinarian about the best option for preventative treatment for fleas, as there are many choices available.
Can FAD be treated with desensitization?
Desensitization involves giving your pet a series of increasing doses of diluted flea antigen over a prolonged period. Sometimes, these allergy injections may be required for life. Unfortunately, desensitization is not considered a successful treatment for FAD in dogs and is rarely used. However, do not confuse desensitization therapy with corticosteroid or cortisone injections, which relieve the symptoms of an acute FAD flare-up.
Can FAD be treated with steroids or other drugs?
Corticosteroids are often needed to treat acute (sudden) episodes of FAD and provide immediate relief from intense itching. However, steroid use has significant potential side effects. Steroids, most commonly prednisone, can be used in most dogs for short-term relief while flea control is implemented. The goal is to use the lowest dose of corticosteroids possible, as infrequently as possible, preferably on alternating days or every three days. Combining corticosteroids with omega fatty acid supplements may be an ideal regimen for many patients.
Oclacitinib (Apoquel®) and Lokivetmab (Cytopoint®) are alternatives to steroids that may also help address itching and inflammation of FAD. Antibiotics may be necessary if your dog develops a secondary bacterial skin infection due to the scratching.
Your veterinarian will discuss the advantages and disadvantages of the various treatments for FAD during the examination and will recommend the safest and most effective treatment for your pet's needs. Prevention is essential, simple, and inexpensive.
