Pet Vet: Fleas become resistant to typical treatments

May 27, 2014

Have you noticed an explosion of fleas with your companions this season? I certainly have and so, apparently have Esteban and his dog, Carter.

Carter is a 5-year-old English bulldog living with Esteban and his family in Farmington, Calif. He has the run of his house and his half-acre back yard, which he shares with various wild creatures and a stray cat or five. Carter, as one might expect having to share his space with many other creatures, has had a history of flea infestation, usually in the spring and summer. Esteban has used Frontline, a topical flea treatment and preventative, to combat Carterís flea population and has had good success, that is, until this year.

Starting in late March, Carter began to show the telltale signs of tiny livestock inhabiting his hair coat. He would spend inordinate amounts of time scratching, especially his tail base and inguinal area. Esteban knew the behavior having seen it in the past with Carter and indeed upon closely examining him, he discovered a massive load of fleas.

Out came the Frontline with Esteban fully expecting a massive flea die off. Unfortunately, that was not the case. Within one week of application, Esteban was finding just as many fleas on Carter as he did pre-treatment. He wants to know: What is going on?

Esteban is experiencing what we as veterinarians have been seeing for some time now and that is a decrease in efficacy of Frontline. Over time and with constant exposure to flea preventatives, fleas will eventually develop some degree of resistance to the product. This resistance is passed on generation to generation among the fleas, rendering the product less and less effective. This may indeed be happening with Frontline. It is for this reason that I have stopped recommending Frontline for flea prevention in my dog and cat patients.

When addressing a flea infestation as is the case with Carter, it is important to understand the flea life cycle. Only 5 percent of the total flea population lives on the dog. These are the adult fleas. The female flea, after taking her blood meal from the dog, lays her eggs that drop off into the environment, which in Carterís case includes inside the house and out in his half-acre yard. The eggs develop into a larval stage, which then becomes a pupae, which then hatches as a new adult flea. These new fleas immediately begin their bloodthirsty trek to their new victim as the cycle begins anew.

For Carterís particular situation, I would recommend Esteban try a new topical flea preventative called Activyl. This will destroy Carterís flea population and prevent new colonization as well. One of the great things about this product is that the flea does not have to bite Carter in order to die. After all, it is the flea bite that irritates the dog! The flea simply contacts the product and itís off to the graveyard.

Remember, only 5 percent of the total flea population resides on the victim; the other 95 percent lives in the environment. Since Carter appears to be dealing with a rather large total population of fleas, it would be advisable to not only treat him with Activyl but to also treat his environment.

A half-acre yard would be a tall task to take on as a homeowner, though it can be done. Otherwise, an exterminator can be called in. The house itself however is manageable as a do-it-yourself project.

Esteban needs to talk with Carterís veterinarian to discuss Carterís specific digs and devise a coordinated assault on those blood sucking fleas with the ultimate goal of giving Carter a flea-free life.


McClatchy-Tribune Information Services