Fleas don't always die off in the cold weather. They oftentimes go into hiding during the cold season—and may even seek refuge in the warmth of your home. While chances of an infestation on your pet might decrease in the fall and winter seasons, foregoing flea prevention can allow small numbers of fleas to multiply. Don’t wait until your pet and home are swarming with fleas- keep them away entirely with the proper preventives.

Fleas enjoy temperate weather with high humidity, so we often notice them during the warm summer months. But once the days get shorter and the weather gets colder, we feel at ease and see fleas a lot less often. But just because flea infestations aren’t as common in the colder seasons doesn't mean that the pests are gone. Fleas reproduce year-round where environmental conditions permit, especially in southern climates where even the winters are temperate.
Efficacy of Prevention
Many pet owners opt to use flea medications only after an infestation occurs. Though they may believe this will save them money on preventatives like Advantage® II for dogs and cats, preventing an infestation entirely can save pet owners from sudden and excessively large costs.

It’s no surprise that pet owners tend to let up on flea medication during the cold season; however, even when a pet is infested with fleas- only 5 percent of them will actually live on your pet. 1 The rest will be in the pet's environment where they are less visible. This fact remains true in the winter months with fleas surviving in the warmth of the indoors.

Because flea infestations often spread throughout a home, it can be costly to remove them from an infested area. Simply treating your pet after an infestation has occurred is often insufficient, as the fleas hiding in your pet’s environment can infest your pet as soon as the treatment has stopped working. This cycle will continue unless the fleas are eradicated from your pet’s daily environment.

Additionally, these fleas can transmit diseases to your pets that can be costly to treat. Fleas can carry diseases like cat scratch fever and can even transmit tapeworms to your pet; in fact, tapeworms can even be passed from fleas to humans. This means that an infestation in your home can put both you and your pet in danger.

Aside from the costs, it can be a great deal of effort to have to treat fleas after the fact, combing through fur and checking furniture to ensure that the infestation has been totally eradicated. Using a preventive can help you forego this effort by ensuring that fleas never enter your home.
Treatment for Cats
One of the leading brands of flea treatments for dogs is K9 Advantix, which also works to repel ticks. However, K9 Advantix contains an ingredient guide that makes it unsuitable for flea treatment on cats. If you are a cat owner, there are still a variety of flea treatments available. Among them are Seresto® and Advantage II®, both of which are flea preventives available in formulations for cats or dogs. For more information on flea preventives, you can look at this buyer’s guide.

Using a flea treatment instead of a flea preventive is still an option for risk takers, but we can only see what kind of risk they’re taking if we compare the efficacy of flea repellents to a case in which no flea repellant is used. Although it depends on the ingredients of your preventive product; studies have shown that flea medication with a particular amount of imidacloprid, one of the active ingredients in K9 Advantix®, is 98.43% effective over the 30-day period for which many topical flea preventives are labeled. Though the study used the original formula for K9 Advantix® rather than the new and improved formula for K9 Advantix® II, the new formula still uses similar concentrations of both imidicloprid and permethrin. 2

Do not use K9 Advantix® II on cats.
K9 Advantix, Advantage and Seresto are registered trademarks of Bayer.

1Grace SF. Fleas. In: Norsworthy GD, Crystal MA, Grace SF, et al, eds. (2006). The Feline Patient. 3rd ed. Ames, IA: Blackwell Publishing; 106-107.
2Science Direct, Efficacy of a combination of imidacloprid 10%/permethrin 50% versus fipronil 10%/(s)-methoprene 12%, against ticks in naturally infected dogs