Q: We have a 3-year-old indoor-only cat who we noticed began scratching at her ears and hind end about four months ago, to the extent that she was causing damage to her skin and hair loss in these areas. We used a flea comb on her and found that she had fleas, so we ordered Bravecto, which I was told is a good product. We have applied it twice, and she continues to scratch in these areas. We also occasionally find a flea on her, but it seems like there are far fewer fleas than we had seen before. Can you provide some ideas about why this product might not be working?
A: Thanks for getting in touch, and I am very sorry to hear about your cat’s flea problem. Fleas are a common issue in cats, even those that are indoors only, and they can be challenging to eradicate, but perhaps a few thoughts might be helpful in finding a solution to this persistent problem.
An important aspect of flea control is understanding their life cycle. Perhaps the easiest place to start is with an adult female flea, which will feed on the blood of its host to start the reproductive cycle. After feeding, the flea will lay eggs, which will usually fall off the host into the environment. These eggs hatch, releasing flea larvae within about two weeks if conditions are appropriate. These larvae, which look a bit like small worms, take about 20 days to develop to the pupae stage, during which time they feed primarily on the waste produced by adult fleas feeding on hosts after it falls into the environment. After entering this pupal stage and spinning a cocoon, it takes up to three weeks for pupae to develop into adult fleas, which then emerge from their cocoons and seek out hosts to begin the life cycle once again.
An important point here is that eliminating fleas only on pets is not sufficient to eradicate
fleas from a home. To fully address flea infestation in a home, simultaneous aggressive measures to address adult fleas, larvae, and pupal stages both on all pets and in the home environment must be undertaken.
The environmental issues can be addressed by thorough vacuuming and cleaning of floors, bedding, and furniture in conjunction with use of approved spray, aerosol, or dust-based pesticides. In extreme cases, professional extermination services may be required.
Treating fleas on pets involves the use of either oral, spot-on, or collar-based insecticides, and you can talk with your veterinarian about which product might be best for you. Some of these products (like Bravecto) require that fleas ingest a blood meal from the treated host to work effectively (as opposed to being effective merely by having fleas contact them).
Importantly, many cats are allergic to flea saliva, so when they are bitten by fleas, they can become very itchy. This can cause them to scratch so intensely that they injure their skin while doing so.
In your case, it is quite possible that by not addressing the environmental aspect of flea infestation, you are not addressing the larvae, pupae, and adult fleas in the environment of your home. If this is the case, the Bravecto may be working quite well, but your cat may be constantly reinfected by fleas that originate from the untreated environment in your home. In addition, since Bravecto requires that fleas bite your cat to be effective, this may be causing flea allergies in the process.
I hope this is helpful, and please work closely with your veterinarian to most optimally address this frustrating issue.
