Signs your pet has FAD (Flea Allergy Dermatitis):

We all know that fleas are irritating and unpleasant, and we’ve talked about the number of diseases they can carry. But did you know that your pets can also be allergic to flea saliva? This condition is called flea allergy dermatitis, or FAD for short. Is your pet extra sensitive to fleas? Let’s talk about the key points with pets affected by FAD. 

What is FAD?

Flea allergy dermatitis (FAD) is a hypersensitivity in pets caused by an overreaction of the immune system to flea saliva. In essence, pets can be “allergic” to flea saliva. Fleas’ favourite places to bite are around the head and base of the tail so cats and dogs may have allergic reactions in these areas causing redness, scabbing, inflammation and hair loss. There is often this characteristic pattern, but pets can be itchy anywhere on the body. Often, the changes are mild and can be resolved with treatment alone. But in some cases, the reaction is more severe. Strict monthly flea prevention is essential to avoid uncomfortable reactions. 

There is another secondary issue caused by FAD. When pets itch, bite and chew the skin, the normal skin barrier which acts as a protectant from the environment is broken. Bacteria and yeast (fungi) that normally live on the skin then have the chance to overgrow, leading to secondary infection. Owners may notice crusting, pustules, discharge, bumps, etc. These infections can also cause further itching and irritation and require additional treatment. 

How to treat FAD:

Pets experiencing these severe skin changes from FAD more than likely require additional treatment from the vet. This may include oral medications like antibiotics, antifungals, antihistamines, anti-inflammatory drugs, and immune system suppressive drugs, as well as topical treatments such as medicated sprays and shampoos. Pets who suffer from FAD may also experience other common allergies including food allergies and environmental allergies (atopic dermatitis), and may require further treatment. While pets tend to do very well with appropriate treatment, it is important to realise that the condition can become chronic if not treated quickly and appropriately. 

Top tips: 

FAD is a severe individual allergic reaction to saliva after a flea bite. These pets can be extremely uncomfortable as a result of the skin irritation secondary to the allergy. Veterinary care to treat the fleas and secondary skin irritation/infections that can arise is typically required. Parasite prevention monthly year round is essential to achieve success and a happy non-itchy pet! 

For more information about persistent flea infestations, check out our blog “Fleas Fleas Fleas – Keep Treating Monthly and Still Seeing Fleas”. In this blog you can find more helpful tips on how to successfully treat your pets, as well as your home. 

Dr. Kirsten Ronngren, DVM MRCVS

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