Pet Talk: Flea fight? Know your adversary

By Sarah Netherton/University of Illinois College of Veterinary Medicine

“You have to understand the flea life cycle if you want to rid your pet and household of these pesky external parasites,” said Allan Paul, a veterinary parasitologist at the UI College of Veterinary Medicine in Urbana. “Appropriate treatment must take into account the different stages of the flea’s life.”

According to Paul, the cat flea is the type of flea that is commonly seen on both cats and dogs, while the dog flea is rare. Cat flea eggs hatch into larvae within two to five days and enter the pupa — or cocoon — stage the following week.

They then develop into adult fleas within one to two weeks, if an appropriate host is available. In the Midwest, the cycle from egg to adult can happen in about a month.

When the flea is in the pupal stage of development, the exterior of the pupa is very sticky. This sticky coating acts as protection for the flea, as the pupae are resistant to insecticides, and are therefore hard to kill. Fleas in the pupal stage are what overwinter in peoples’ homes.

What triggers adult fleas to emerge from these pupae? Paul explains that the pupae wait to detect heat, carbon dioxide and vibrations — all signals that a warm-blooded host is nearby — before emerging. Since pupae need movement to hatch, vacuuming is a good way to inadvertently hatch them.

The vacuum bag should be changed or canister emptied to keep the fleas from spreading around the house by means of the vacuum.

Pets can get fleas from the outdoors, as the cat flea can be found on various species of wildlife, including raccoons and opossums.

“Fleas can cause what is called flea allergy dermatitis in cats and dogs, meaning itchy skin,” Paul said. “Although fleas themselves are rarely detected on animals, since pets tend to eat the fleas, the pet will be extremely itchy.”

If you suspect your pet may have fleas, it is important to bring the animal to see a veterinarian to receive treatment and relief from itching. The veterinarian will examine the pet for live fleas, which may be seen jumping on the pet or more likely for what is called “flea dirt” (flea poop) on the pet.

If a pet has evidence of fleas, the veterinarian can offer various forms of treatment. Paul recommends treating pets preventatively for fleas year round, since fleas are able to survive the winter in peoples’ homes.

An archive of pet columns from the UI College of Veterinary Medicine is available atvetmed.illinois.edu/petcolumns/. Requests for reprints of this article may be directed to Chris Beuoy, beuoy@illinois.edu.