What is Flea Allergy Dermatitis (FAD)?

FAD (Flea allergy dermatitis) is a condition which refers to developed hypersensitivity caused by flea bites, in domestic animals. Along the years, fleas were divided into more than two thousand species. The one responsible for causing miliary dermatitis in cats is Ctenocephalides felis. There are certain biochemical combinations, such as enzymes, amino acids and polypeptides in the CF’s saliva which trigger hypersensitive Type I and Type IV reactions on the animal’s skin.

Flea infestations are most common in the southern parts of the globe (all year long), while in the northern parts of the globe we have seasonal infestations (mostly in summer). These infestations occur as a result of extreme heat boost the development of the fleas. You can witness variable clinical depending on the cats’ systemic sensitivity. Some cats which are more sensitive to flea bite reactions can develop seriously acute clinical signs. While other get by with minimal to non-detectable changes on the surface of the skin.

Flea Allergy Dermatitis

Flea Allergy Dermatitis FAD

After the cat has experienced flea bites, the first manifestation comes in form of populous dermatitis. This is the result of the systemic allergic reaction. Following the systemic allergic reaction, the papules become crusted, they can be spotted on predilection areas on the body as the face, the back, and the neck. Further on as the process develops, the generalized pruritus (itch), as a severe manifestation of FAD, is the main reason cats start to scratch, chew and lick the affected, inflamed areas of their bodies. Most commonly this inflammation is followed with alopecia- hair loss.

How to treat Flea Allergy Dermatitis (FAD)

In order to prevent flea infestation and completely eliminate flea population in the home its surroundings, you must keep your pet free from FAD at all times. In case the disease occurs, it may take a longer time period for cleaning up adults, larvae, and eggs as a result of the infestation.

Flea Allergy Dermatitis

Flea Allergy Dermatitis FAD Dog

First, you should make sure your cat is not susceptible to infestation by using IGRs (Insect growth regulators) and insecticides, which you should apply topically on the animal. IGRs have proven positive effect in fighting the flea problem, they have extended residual effect and quite convenient dosage formulations. The effect lasts no longer than a couple of months. In order to spread throughout all surface of the body, the compound needs several hours (approximately 24 hours).

After flea infestation, another demanding task is exterminating your home (rugs, carpets), bed sheets, back and front yard, dog beds, and dog houses. You need patience and strong efforts in order to achieve positive results. Following the first treatment with insecticides, the second treatment should be executed after one week. In a seven-day period, the adult forms emerge from cocoons. This is why you should repeat the exterminating process once more.

For controlling the secondary skin diseases and chronic pruritus you must apply systemic glucocorticoids, systemic antibiotics (pyoderma) and allergens. The glucocorticoid of choice for FAD is prednisolone at a rate of 0.5-1 mg/kg/d. The application of prednisolone should be discontinued once you gain control over the flea population. Based on the bacterial cultures isolated from the skin lesions, the vet should prescribe proper antibiotic therapy. We still are facing controversial claims related to the effectiveness of allergens extracted from actual fleas. As well as, the hyposensitization process of applying them and the subsequent no reactivity to bites show good results.

If you are concern about this issue, read the article about Increase in Flea Allergy Dermatitis in Dogs and Cats on our blog.