Cats and Permethrin question

[sloanbychoice]

I couldn’t find the info I need...
I know that Permethrin is very toxic to cats.
Does anyone know how long after application it is safe for a cat to be around?

 

[Rainwing]

http://npic.orst.edu/factsheets/archive/Permtech.html
Permethrin is a very stable compound. Taken from the page,

• The average half-life of permethrin in aerobic soils is 39.5 days, with a range from 11.6 to 113 days.
• Permethrin binds tightly to soil and is broken down primarily by microorganisms, but also by photolysis.

"The "half-life" is the time required for half of the compound to break down in the environment.

1 half-life = 50% remaining
2 half-lives = 25% remaining
3 half-lives = 12% remaining
4 half-lives = 6% remaining
5 half-lives = 3% remaining"
I would say 4 half-lives, or 156 days / 5 months would be the optimal time for a majority of the permethrin in the coop to break down, since chicken bedding is somewhat similar to soil, and thus your cat will have no serious health effects.
Permethrin is toxic to cats because they cannot metabolize it. Personally, I would let my own cat around the coop after 2 months, even though all of the permethrin may not have broke down by then. This is because the toxicity depends on dosage. Most of the fatal cases of permethrin on cats is from owners applying dog medicine directly onto its fur, and the cat licking its fur and consuming a large dose. I would imagine the presence of permethrin over a large coop to be more diluted unless you had a large mite problem.
"In rats given oral doses of permethrin, the excretion half-life was measured at 12.3 hours for plasma and from 9 to 23 hours for certain brain and nervous tissue, including the medulla oblongata."
My cat never stuck around the coop much other than going for a quick walk, but I don't know about letting the cat hunt mice as soon as a month after permethrin treatment. It doesn't have as long of a half-life in a mouse from the coop, only about five days and it's gone, but it would definitely result in the cat consuming permethrin which is riskier than it walking around the area.
So 3-5 months at the soonest. Maybe 2 months if you're like me.
This is a guesstimate answer, it would be cool if someone else had experiences with it.

 

[sloanbychoice]

Thanks. I appreciate the reply. I had pretty much given up on anyone answering this.
Seems like there are a lot more unanswered threads these days...

That’s a lot longer than I had guessed with my complete lack of knowledge.
Luckily, nothing has happened in the mean time.
We have an outside cat that we inherited when we bought this house. She’s a great mouser, and she loves to sit down at the coop and catch the mice and pack rats.

I’ll cross my fingers that everything continues to go ok. I have another treatment this weekend.

 

[Folly's place]

I use permethrin in the coop and on the chickens when there's a 'bug problem', and keep the barn cat out of the area until after it's all dry. At that point it's fine to walk on it, and the amount the cat might pick up is minute. We've never had a problem with it!
Using permethrin on the cat is where bad things happen!
Mary

 

[sloanbychoice]

Thanks Mary!!
We got lice and mites together so we’ve been having to do repeated treatments.
I don’t want anything horrible happening to this cat.