New, Better Flea-Killing Products Available

los angeles veterinarianThe long-term control of fleas remains one of the consistent challenges presented to pet owners. It would not be an exaggeration to suggest that during some months, almost 50% of the veterinary medical cases seen involve skin problems related to fleas.

While preventive or product combination strategy is still the best advice, two new flea-killing products on the market - Activyl and NexGuard - are highly effective.

I reviewed some of the newspaper articles I had written on the topic over the past 20 years, and while the names of the products have changed, the basic themes have not: resistance to insecticides will always be a problem, and flea prevention is still preferable to trying to treat them after the fact.

First, let’s update the current flea product situation. In an article from 2004, I noted how Advantage and Frontline had become the mainstays of successful flea “adulticide” treatment, having replaced most older products, such as the organophosphate dips, collars, pills and pyrethrin sprays. And yet at that time, even after just 6 or 7 years since they had been introduced, there were already some areas where the fleas were no longer well controlled by these products. My recommendation was for owners to use a two-pronged approach to ridding fleas, with year-round use of an insect growth inhibitor (IGI) as the mainstay product, and the use of a flea adulticide as needed or reserved for use with pets who had very severe flea allergies. The purpose of the IGI was to prevent fleas from accumulating in the environment, and to do so in a way that was safe (vertebrates weren’t affected at all by the products) and reduced the tendencies for fleas to develop resistance to products since it wasn’t a “cidal” product.

los angeles veterinarianWell, flash forward to today, and sure enough, the “wonder products” of yesteryear have been relegated to the ineffective levels of the old-time flea collars. For the majority of pets, Frontline and Advantage are almost worthless for meaningful flea control; flea resistance is evident in the way that one finds many fleas living and reproducing on pets within 7-10 days from the time of treatment. In one study, there were actually more fleas found after use of one of these products than there was for pets who received a placebo. With that kind of result, it is no wonder why one can’t reduce the fleas in the environment, which is the source for new fleas infestations.

Fortunately, several years ago a new group of flea adulticides became available: Comfortis and Vectra. They had a slightly different mode of action than the previous generation of adulticides, and so fleas were very susceptible to their activity, which lasted a full month or more. Pet owners were genuinely pleased with their high degree of effectiveness, as well as their options of oral or topical preparations. However, even after just a couple years, some owners noticed that the classic itching symptoms from flea bites was starting to show in the 4th week of treatment, suggesting that resistance might already be developing against these newer products.

nexgard flea killerWithin this past year, another set of new flea adulticides has come to market, providing another chance to gain the upper hand against fleas. Activyl and NexGuard are the newest flea adulticides, and they have shown excellent effectiveness in studies and real-world applications. Activyl has even been singled out for its qualities by leading experts on fleas within the veterinary field, a rare occurrence which speaks for just how good it is.

Still, for all their praises, these new products are of the adulticide class—one can assume that they will also ultimately see fleas become resistant to them. Therefore, I believe the advice from a decade ago is still valid: use prevention whenever possible. If owners relied upon an insect growth inhibitor, such as lufenuron (contained in Sentinel or Program), & reserved adulticides for those that truly need it or in combination with an IGI, they would extend the time before fleas become resistant to the newest products, hopefully allowing time for new products to take their place. Even setting up a rotational use of the various adulticides, lessening the chance for a population of fleas to establish itself that is resistant to the predominant insecticide, would be an improvement over continuous use of the same adulticide until it failed.

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