Understanding Flea Products

By Barb Hoover

We often hear clients complain that their dog still has fleas even though they treat monthly with a topical or oral product. It is assumed the products are not working.  In reality, they likely are working, just as promised, but many people do not understand just how they work and their limitations.

Topical and oral products do not stop a dog from getting fleas. The fleas have to come in contact with the animal or the animal dander to suffer the effects from the pesticides. The products do not give an instant kill. It can take twelve hours to kill the fleas. In that twelve hours, they are able to bite, causing an allergic reaction and reproduce.  

The Advantage Multi insert explains: “Advantage Multi for Dogs should be administered at one-month intervals. If the dog is already infested with fleas when the first dose of Advantage Multi for Dogs is administered, adult fleas on the dog will be killed. However, re–infestation from the emergence of pre–existing pupae in the environment may continue to occur for six weeks or longer after treatment is initiated.”

That is very important information. One thing it does not approach is that the above is a controlled scenario. If the environment is getting re–infested during that six weeks from other animals, like stray cats or dogs, the flea population is continually growing. Additional fleas are being dropped in the environment and reproducing. When those jump onto the pet, they also need up to twelve hours of contact to be killed by the products. With only topical and oral products being used, it is a never ending cycle of fleas for the pets.

The topical and oral flea products are meant to prevent infestations. If the environment is clear of flea infestation, the products will usually kill any fleas a pet might pick up on a walk or from the occasional stray that wanders onto the property. The kill is usually fast enough to prevent a huge population growth and infestation.

Unfortunately, many owners only use the products after they see fleas on the pet. At that time, the environment is usually infested or at least has a good number of flea eggs left around to hatch out. 

If an infestation is present and the dog is continually picking up fleas, it is important to find the source. They come from somewhere. They do not just magically appear on the dog.  They must be killed there, at their source, in order for the dog to remain flea free. In most cases, that requires spraying the yard and the house. This is not a one-time thing. The sprays do not kill the fleas in every part of their life cycle. Some will kill the adults and the larvae. Some will kill the eggs. None will kill the egg, larva, pupa, and adult stages. The treatment needs to be done every 10—14 days, for approximately six weeks to catch and kill the fleas at all stages.  

Once the environment is clear, and steps are taken to avoid re–infestation from roaming animals, the once a month products can usually do a great job keeping an infestation from occurring again. But the owner may still see the occasional flea on the pet. Remember, it can take up to twelve hours for them to die. For myself, if I see two or three fleas on a pet that is regularly treated, I consider the product doing its job.  If I see a dozen or more fleas on a pet that is regularly treated, the environment is in need of treatment.