Flea Allergic Dermatitis


Flea allergic dermatitis (FAD)

Fleas are one of the most common causes of itching in dogs and cats; however, very often it is difficult to see the fleas as pets tend to remove them when grooming. This is especially so in allergic pets, because they groom more often when itchy, or when they have skin lesions. Fleas can also be removed during bathing and in my experience intermittent use of flea products also makes them more difficult to find. Therefore the absence of fleas, or flea dirt, during a clinical examination does not rule out FAD.

Although there are serum and intradermal tests for the diagnosis of flea allergic dermatitis, ultimately response to good flea control supports the diagnosis as both types of tests are able to show false positives and false negative results. This is because flea bites can induce immediate, late phase and delayed type of hypersensitivity responses.

Understanding the flea life cycle will result in a more successful outcome.

While fleas are found on animals, a large proportion of the intermediate stages can be found in the environment. It is therefore imperative to treat the pet and its environment (indoors and part of the outdoors). This is referred to as integrated flea control.

Flea control should be maintained for life and should include all in contact animals and, if possible, all premises regularly visited. (e.g. friends' and families' homes and workplaces)


Environmental treatment

  • Read and follow manufacturers precautions before using any product

  • Vacuuming

  • Indoor environment thoroughly including carpets (including areas covered with furniture), settees, under cushions, skirting boards

  • Outdoor environment should include garage, cars, outdoor kennels, etc

  • Remove or tidy areas where there are decaying leaves, compost heaps, etc

  • Spray indoor area with a product containing Adulticide (permethrin) - this kills adult fleas

  • Insect growth regulator (pyrioxyfene, S-methoprene, flufenoxuron) - these prevent insect growth and development thereby reducing the flea burden

  • Repeat 2-3 weeks later to remove any newly hatched fleas, thereafter as per the manufactures guidelines, or as recommended by your vet

Pet treatment

  • Treat all the in contact cats, dogs and rabbits

  • A variety of products are available. Some contain adulticide only whereas others contain a combination of an adulticide and insect growth regulator

  • In general, for any product follow the manufacturers' guideline, sometimes; however, the flea control has to be tailored to individual needs and circumstances

  • For heavy infestations you may be asked to alter this for an initial period of treatment

  • If you bath the dog then more frequent treatments may be required

The notes above are only a brief explanation. If you wish to discuss any point further please do not hesitate to contact me.

Anita Patel (Veterinary Dermatologist)


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