How long for cimetidine liquid to leave her body? for small dog-15lb?

I think its causing my maltese poodle to have rapid breathing? She had surgery on wed last wk, abscess anal gland) on Thursday she regurgitated her food-vet put her on 0.75ml of Cimetidine liquid every 8hrs. I believe that is about when she began the panting and rapid breathing. I told the vet-he didn't say anything. I gave her 0.60ml (a smaller than prescribed dose) a few hours ago-Sat at 9pm. How long till this gets out of her system? I called emer vet they said there wasn't an antidote. I read about the side effects on the web and figured that was why she was panting with rapid breathing (body moving up and down). She is eating, drinking, peeing/pooping. This med can cause insomnia,too. very worried about her. Another night of no sleep-checking on her constantly. I have brought her back to the vet every day after the surgery-for hydration and to check on her. Where ever they shaved her, the skin it flared up very red and irritated. I think could be food allergies..? Just worried about her. thanks for your advice.

i personally think it is ridiculous the vet even prescribed this ... for use in dogs, it is not the same as people, and it seems your vet has prescribed it for people reasons ... i would stop it right away ... and the drug itself has a short half-life so should leave the dogs system in under a day ... the half-life is approximately 2 hours for cimetidine ... when my dog had surgery, where she was shaved got red and itchy too but cleared on it's own ... and no need to keep bringing the dog to the vet for hydration ??? what is that about ... i sure hope you are not paying for all these follow-up visits ... i can see the surgical area needing to be checked, but hydration, you already said the dog was drinking ... and it would not be unusual for a dog who had been under anesthetic for a surgery (the dog was probably fasted before the surgery too) to vomit the next day ... and to prescribe cimetidine is so beyond comprehension, you could have just given the dog a gravol ... i wonder how much this vet is making off of you ... i hope your pup is feeling better soon ... i don't think it is food allergies, it is just a dog recovering from surgery ...