Now lambda-cyhalothrin is a fairly mild pyrethrin. The reason the label didn’t encourage the induction of vomiting is because in significant doses it can cause vomiting itself. As well, it can irritate and burn the throat/stomach tissues as it is ingested and then brought back up. Otherwise, just to note, signs of poisoning with this would be continued vomiting (over hours), drooling, and neurological signs (tremor, wobbliness,weakness).
With all this in mind, the vomiting hopefully has removed enough of the toxin to avoid those more serious signs. Therefore, what we need to focus on is limiting any residual material absorption while supporting the throat and stomach over the next 24 hours. First, I would note that if we did want to err on the side of caution you could also consider administering activated charcoal at this stage. This is available over the counter from the pharmacy (ask for the high strength version, not the one for gas) and works by binding any remaining material in the stomach. For activated charcoal, we tend to give 1-4 grams per pound every 8 hrs. This can be mixed with food to be fed or with water to syringe feed (do note that it stains, so keep it away from white carpets/clothes). This will just limit how much is absorbed and reduce the intoxication risk here. And I would note that you could even add this to a bit of lactose free milk (or just give some plain anyway) since that is very good for just neutralizing caustic chemicals in the stomach. If you don't have lactose-free, you can use regular but just be aware that it could cause a bit of loose stool.
Otherwise, we will want to address stomach upset while protecting the throat. To do so, we'd want to use an antacid. There are a number of antacids that are available over the counter and pet friendly. I would advise only treating with one, but the two I tend to use are Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) or Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac). If you can obtain liquid versions of these that would be ideal. Or you could also use Milk of Magnesia (magnesium hydroxide at a dose of 0.5tsp every 8 hours), just as these will better coat the throat as they go down into the stomach. And whichever you choose, these are usually given 20 minutes before offering food (to allow absorption) and of course you want to double check with your vet before use if your wee one has any pre-existing health issues or is on any medications you haven't mentioned.
Once that is on board, you can also use a light diet like rice with boiled chicken, white fish, or cottage cheese. Again these will just help absorb any left, is easy on the stomach/throat, and easy to digest. This can be continued for a few days before weaning him back to his normal food.
Overall, the vomiting has at least lowered some of those more severe toxicity risks. That said, we need to tread with care and monitor his throat/ stomach comfort. If we can do that and he shows no signs for the next 48 hours, we are happy. But any drooling, sores, appetite loss, or belly pain; and we'd want t him to see his vet for a check. They can assess any lesions and start him on further gastroprotectants +/- gut safe pain relief by injection to just soothe this and aid healing if need be.
I hope this information is helpful.
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