I have two cats and we haven’t had any issues that I could see.

I make 100% sure they can never be exposed to it when it’s wet, but they’ve been around me in treated clothing, escaped the house and walked through treated (dry) grass, been around dogs that have been treated with it, etc.

Given the number of people that have cats and dogs living together who are treating their dogs with it monthly, it seems relatively safe if used properly and cautiously.

Seems there are a couple of chemicals that act as anti-tick. We're using Seresto collars for our two dogs (no ticks in a decade of usage), which seems to be using Imidacloprid (anti-fleas) and Flumethrin (anti-ticks).

So at least there seems to be two ingredients, there are probably more.

But nice to see we’re finally getting for humans what pets have had for a while for ticks.

We began treating our boots with diesel to try to repel them. That worked to a point. It didn't take long to reveal the shortcoming in that method - diesel fuel soaks through the leather and easily enters the skin. It ruins the boot leather and burns your skin so that wearing anything on your feet is very painful so we abandoned that method.

After looking at options we decided to use cattle ear tags because each cow only uses one and it keeps them tick-free. After reading all the warnings about safe handling - wear gloves, avoid skin contact, potential reproductive harm, cancer risk, etc. - we decided that it made no difference. We realized that this had to be absorbed through the cow's bloodstream from the puncture on the ear and since every cow we had ever seen had an ear tag, this meant that this chemical was present in every steak or burger we had ever eaten so wearing one long enough to complete the part of the survey with the tick problem wasn't going to increase our risk of any adverse effects.

We bought a pack of tags and each hung one on a boot and never had another tick.

I don't have any known health issues to report here 40 years later. Totally anecdotal information from what is likely to have been a low-dose, short duration exposure event.

Not sure how true it is, but the marketing for the collars we use claims that eventually the chemicals spreads to protect the full body, even if the collar is just around the neck.

That’s what the medicated pet collars do.

Part of the advantage of collar-absorption is that you can use a molecule that readily breaks down/inactivates in digestion. And avoid sharp peaks in blood levels.

Tough woman. She is missed.

and how do you manage this?

AFAIK there has only been one documented case of it killing a kitten and it drank the liquid form, unknown quantity. Baby animals do not yet have fully formed livers to metabolize the sodium channel blocker. Insects on the other hand do not have a liver. They use body fat to detoxify but it isn't fast enough or volumetric enough to handle the sodium channel blocker in large amounts relative to their size.

Study of 286 cat/permethrin cases in London: https://journals.sagepub.com/doi/full/10.1016/j.jfms.2007.05...

Study of 750 cases in Australia: https://journals.sagepub.com/doi/full/10.1016/j.jfms.2009.12...

...we don't track this stuff nearly as well for pets as we do for humans but seems to have pretty robust evidence of toxicity.

https://www.amazon.ca/OnGuard-Pro-Perm-Residual-Non-Flammabl...