Can Fleas and Ticks Become Immune To Treatments?

You apply your pet’s flea preventative exactly as directed, yet your dog or cat still has fleas. What’s going on? 

Many pet parents are wondering if fleas and ticks are becoming immune to active ingredients in preventatives. Though it is possible for pest populations to develop a resistance to pesticides, there may be other factors to blame for stubborn insects that plague pets. 
 

How Do Flea and Tick Preventatives Work?

To better understand why you might still be seeing fleas and ticks on your pet, it’s important to get to know how your pet’s preventatives work.

Flea and tick preventatives are applied topically through the use of spot-on applicators, sprays, or a flea collar. Or, they’re administered orally as a chewable tablet that’s prescribed by your veterinarian.

Oral and topical flea and tick preventatives work similarly. 

Topical flea and tick preventatives slowly release the active ingredient over your pet’s whole body via their skin’s natural oils. 

Oral flea and tick preventatives work by absorbing into your pet’s bloodstream.

After a flea or tick comes in contact with the active ingredients in the product, either by landing on your pet or feeding off their blood, they’ll begin to die off within 30 minutes but may take up to 48 hours to eliminate. Many products also contain an insect growth regulator (IGR) that prevents pests from reproducing.

This means that pests can still re-infest your dog or cat if fleas and ticks are present in your home, yard, or anywhere your pet goes, like parks, beaches, and hiking trails.
 

Can Pests Become Immune To Preventatives?

Yes, but so far, it’s not been documented as a factor in the rise of flea and tick infestations because of the use of insect growth regulators (IGRs). 

It’s possible for parasite populations to become more resistant through evolution. When a gene mutation enables some parasites to survive a pesticide, they’ll be more likely to reproduce, passing the mutation onto their offspring.

However, flea and tick preventatives that include IGRs prevent pests from continuing their lifecycle. A small percentage of insects may show gene mutations that make them harder to kill. But IGRs render them unable to mature, lay eggs, and pass the mutation onto their larvae.
 

Why Your Pet’s Flea Treatment Isn’t Working This Year

It’s not your imagination; fleas and ticks are getting worse every year. Flea and tick prevention methods that once worked well may no longer seem as effective, and you may find your pet and your home overwhelmed with fleas even if your pest prevention routine has not changed.

According to the Companion Animal Parasite Council (CAPC), shorter, milder winters in many regions are leading to steadily increasing populations of fleas and ticks that affect pets. What’s more, heartworm disease in dogs and cats is on the rise due to the increased prevalence of mosquitoes that spread the parasite.

It takes five straight days of below-freezing temperatures to kill fleas outdoors. Without a deep freeze to kill off pests, parasites are emerging earlier in the spring and survive long into the fall and early winter. And with even just one unseasonably warm day in the winter, fleas, ticks, and mosquitoes can hatch, come out of dormancy, attack pets, and lay eggs at any time of year across many regions.

With the ever-changing climate conditions, your pet’s flea and tick prevention needs to change, too. Pets need flea, tick, and heartworm protection year-round to help keep parasite populations under control.
 

How To Keep Your Pet Protected Against Fleas And Ticks

Shorter, milder winters are leading to booming pest populations outdoors, which in turn makes it more likely that they’ll find their way indoors or hop on your pet when they go outside.

To fight back, you’ll need to keep your pet protected year-round with a flea and tick preventative that’s tested to be safe and effective against multiple pest life stages.

Prevent reinfestation by treating your home and yard for fleas and ticks and check your pet for pests when they come inside after spending time outdoors. 

Need help protecting your dog or cat against pests? Talk to your veterinarian or make a same-day televet appointment with VetLive.