My name is***** and I am sorry to hear that your dog ate extra rimadyl tablets. Based on your history, is it safe to assume she weighs about 50 pounds and is taking 1/2 of a 100mg tablets twice daily?
If this is correct, she should be fine this evening. The dose she ingested is 13mg/kg which is definitely too much, but only enough to cause vomiting and diarrhea. Much higher than that and we run into problems with the liver and kidneys.
For tonight, I would recommend giving 20mg of Pepcid (famotidine) to reduce the acid in her stomach and monitor closely for vomiting and diarrhea. If she starts vomiting or having diarrhea, I recommend taking her to your regular veterinarian in the morning.
I would skip the morning dose and then continue tomorrow evening as previously directed.
In the future, if she steals more rimadyl, I would recommend inducing vomiting with hydrogen peroxide immediately. You can force her to swallow about 2-3 tablespoons and she should vomit within 10 minutes. Vomiting is useless 30 minutes after the pills are ingested which is why I did not recommend it tonight.
I hope this answer helps you. Feel free to contact me if you have any further questions.
Kansas State University
College of Veterinary Medicine Class of 2001