Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 16 years of experience. I look forward to working with you.
I am sorry to hear Murphy decided to eat the whole bottle. Assuming he is probably about 40-50 lbs at this age, and that there are 100 to 200 tablets per bottle (usually around 2.5-3mg each), then the first step would be if this occurred in the past hour to induce him to vomit and bring up what we can. You can take him right now in to see his veterinarian where this can be done or you can do it at home by giving hydrogen peroxide (2 tablespoonfuls by mouth, wait 10 minutes and if nothing repeat once; if still nothing then this won't work). If it has been longer than 1-2 hours after ingestion then there may not be any reason to induce vomiting as it may be out of the stomach.
Overall not a huge worry. You may expect to see some digestive tract signs such as vomiting or diarrhea for the next 24-48 hours, and if severe then he needs to be treated by his veterinarian. He may also be slightly drowsy.
However, you need to check the bottle carefully and be sure the tablets do not have xylitol in it. If so, then this is a medical emergency and the xylitol is a huge problem. You need to rush him in to be hospitalized for this for monitoring the next day.
I am at a point I need to know what questions you have.
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