Categories: Cat Healthparasites

Cat Flea Resistance To Flea Treatments

Cat flea resistance to flea treatments

Can cat fleas build up a resistance to flea treatments? In other words can the species that is the cat flea evolve into something slightly different which cannot be killed by current flea treatments (insecticides). The evolutionary process is one in which fleas which survive are able to pass on their genes and therefore there are more fleas with genes that resist treatments. There are, though, other types of resistance which I won’t go into her for sake of clarity.


Note: On the Mumsnet website a number of mums have said on their forum that they believe that Frontline has lost its effectiveness in killing fleas while Advantage works better.


“Individuals with genetic traits that allow them to survive exposure to an insecticide/acaricide will pass genes on to the subsequent generation, thereby potentially increasing the percentage of a population that can survive subsequent exposure to the chemical”

This short article was prompted by Elisa’s comment. Quotes and information is from the study: Insecticide/acaricide resistance in fleas and ticks infesting dogs and cats by Tad Coles and Michael Dryden.

Using simplified language, resistance was stated as being a trait in the species of insect (e.g. the cat flea) which results in a notable increase in the percentage of fleas surviving treatments.

The conclusion from the study was as follows:

It is possible that cat fleas can become resistant to flea treatments but the only way to find out is to show scientifically “that the parasite population has changed” meaning genetically I presume. As far as I am aware no such research has been conducted.

Therefore, when, for example, a veterinarian’s client, a cat owner, attends the vet’s clinic, and says that the flea treatment is not working because the fleas are not being killed, the response is to check for reasons other than resistance to treatments.

In the words of the Coles and Dryden:

“it is essential to review the history and look for potential treatment deficiency, because the ultimate cause is much less likely to be actual flea or tick resistance. If reduced susceptibility to treatment is seen, then other more common causes must be ruled out before resistance can be considered as likely.”

In other words make sure the treatment is holistic – covers the entire household and is applied correctly. Potential examples of cat flea resistance to common commercially available treatments are much more likely to be a failure of the owner to tackle the presence of fleas effectively and in compliance with well-known guidelines.

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Michael Broad

Hi, I am 70-years-of-age at 2019. For 14 years before I retired at 57, I worked as a solicitor in general law specialising in family law. Before that I worked in a number of different jobs including professional photography. I have a longstanding girlfriend, Michelle. We like to walk in Richmond Park which is near my home because I love nature and the landscape (as well as cats and all animals).

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  • I have nothing put tile in every room and no rugs.I wash pet bedding every other day .My cats have no problem with fleas ,and the outside dogs get sprayed with adams flea spray.It seems to work.

  • Humidity also plays a role. Fleas have to have 50% humidity to live. In the south we've dealt with near 100 degree temps and 90% humidity. Our cats are all indoors and the only thing that's worked is Advantage. Laura even wipes down tables with the natural flea sprays to be sure the eggs are dead. Also used diatomaceous earth and that didn't work. Neither did the $18 bottle of shampoo from the vet, Frontline, the sprays for bedding. Advantage was the only thing to kill them off.

      • From what I've. Read Advantage doesn't kill ticks. But the cats are strictly indoors so that wasn't an issue.

        • Advantage doesn't kill ticks, but none of my cats have ever had ticks, despite spending some time outside during the day. That may be because we're not close to any fields or areas with long grass.

    • When I lived in Cyprus the only flea treatment available was Frontline and even my vet admitted that it no longer seemed to be very effective in killing them. My longhaired cat was worst affected and despite daily combing, combined with monthly treatments, she always had fleas :(

      I'd assumed the flea problem was due to the intense heat and dusty environment, but Elisa's comment about humidity being a contributing factor makes a lot of sense, because Paphos is horribly humid during the summer months.

      Since I returned to the UK I've now switched to Advantage, which so far is keeping all the cats flea free.

      • Thanks for that Michele. Your comment hints at a resistance to Frontline spot flea treatment. I might do some work on that.

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