How to know if treatment is working

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QuestionsCategory: Flea InfestationsHow to know if treatment is working
relics2relish asked 5 months ago

Hello, Adam!
I’m so glad this site is available, thank you!
Both of our dogs have been treated with Hartz Ultraguard Pro 30 day treatment on July 9th. I read on your site that it can take new fleas on our dogs up to 24 hours to be completely killed by the treatment. I’ve noticed a few since treating the other day, but not sure if they are dying or if I’m seeing new ones that have emerged. We have been trying for a month to rid our home of them, we noticed many of them crawling on our one dog, Louie, a couple weeks after we went camping (we applied Frontline Plus on them before camping) So they had a couple weeks to do their thing. I also read here that fleas can possibly stay dormant in their cocoon stage for up to 5 months…so, I’m thinking we mIght be seeing them for awhile since they’ve had time to lay eggs. Should I just look for flea dirt on our dogs to know if the treatment is working?
Thank you for your time!

1 Answers
Adam Retzer Staff answered 5 months ago


Most likely it’s new fleas you’re finding on your dogs. This is because 95-99% of the population are immature stages living in the environment. So, as they mature and emerge, they will seek a host.

Still, if you want to be certain they are new fleas, it may be useful to remove all the fleas you can with a flea comb. Then see if there are more on the dog in a few hours (or longer).

It’s hard to know if a product is working until it’s been around 8 weeks. After treatment, you will continue seeing adult fleas, but they won’t be able to reproduce. So the last generation will be developing in the environment. It usually takes around 8 weeks before this last generation matures, emerges from cocoons as adults, and then dies.

Even if a product is working, you will probably find flea dirt on the dogs. When fleas emerge from cocoons, they find a host and feed right away. Defecation occurs soon after. Many may have a chance to feed and defecate before succumbing to the insecticide.

The cocooned adults can stay quiescent for up to 5 months. Most won’t, but the few that do can cause control problems, and result in seeing fleas for a while. The best way to eliminate these stages is to vacuum regularly. The heat and pressure from the vacuum simulate host cues, which causes the fleas to wake up and emerge within seconds. Your treated dogs walking around and resting in flea hot-spots will also help force the cocooned adults to emerge and then die on the dogs.

Hope this helps,