You don't need to see fleas to have a flea problem | Companion Animal Veterinary Hospital
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You don't need to see fleas to have a flea problem

Matt Young's picture
Dog with flea allergy dermatitis

Why is my dog scratching? I've already treated it for fleas so it can't be fleas that are causing it.

This is a question I get all the time. Flea control is always important especially if you have an itchy dog but just because there are not alot of fleas present doesn't mean that fleas are not the underlying cause of your dog's itch.

Flea allergy dermatitis (FAD)

Dogs with FAD get extremely itchy and irritated by only a few fleas. These dog's are allergic to the flea's saliva that they inject into the animal while they are feeding on their blood. You know how some people with a mozzie bite to the hand just get a small raised area on their hand and other people have their whole arm swollen and itchy, well flea allergic dogs are like the people who get the large amount of swelling. They have an excessive reaction to even a small number of flea bites. The dogs may be so irritated by fleas that they cause self injury through chewing, scratching or rubbing and this can lead to a secondary bacterial infection.

Fleas prefer to hang around the rump, back legs and belly,  so itchiness or signs of damage are usually found in these areas.

If there has been an outbreak of fleas and you treat the fleas and get them under control, these dogs will continue to scratch because the allergic reaction to those flea bites will go on for weeks after. Even one flea bite can cause them to get generalised itchiness for 2 weeks.  


  • removal of fleas is always necessary. In animals with FAD, preventing an infestation occurring is the key to successful management.
    • use a long acting flea product on your dog

    • treat all animals in the household

    • Treat all animals year round (don't stop in winter or when there are no fleas seen)

  • Coticosteroids such as prednisolone are often used to control the itching and inflammation in the skin (cortisone)

  • some dogs may require antibiotics for secondary infections caused by self trauma

For more information on flea control see my previous article on the subject.


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