Hello, I'm Dr. Deb. I'll do my best to help you today.
I'm sorry that Ruffy isn't feeling well.
I typically don't recommend Pepto Bismol (if this is the product you gave) since the current formulations contain salicylates...the active ingredient in aspirin which might worsen nausea/vomiting issues.
However, if the product you used only contained Bismuth, then this isn't likely to have contributed to her issues.
But, to specifically address your question, Zofran (Ondasetron) can be given to dogs and is a reasonably good anti-emetic. It appears to be well tolerated by most patients.
There's a fairly wide range of dosages from 0.05 to 0.5 mg per pound of body weight.
For example, the dose for a 12 lb dog would be 0.6 to 6 mg at one time. I usually dose in the middle of the range so about 4 mg (since the drug comes in a 4 mg tablet) once or twice a day.
I should point out that it would be illegal for me to advise the use of a drug which has been prescribed for another person (or pet) but I can provide the dosage which is what I have done.
I would also withhold food and water for 8-12 hours, just give everything a chance to settle down. Then I'd offer Ruffy a bland diet of boiled chicken
and 20-minute white rice but only just a small amount.
I hope this helps and that he's feeling better soon. Deb