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.
The good news is we use this drug all the time in dogs. A calculated "normal" dose for him is about 0.37mg which is very close to what he might have ingested. So although this is a bit higher than the recommended dose, but it is unlikely to lead to life-threatening symptoms. Dogs tend to handle this drug very welll. You can closely observe him for the next 4-6 hrs, at which time we'll know just how much the drug may affect him. If he becomes unrousable, that's when you need to get him to a veterinary emergency clinic. Some dogs may experience a paradoxical dysphoria (this means vocalizing, out of it, possibly hyper excited) that merits veterinary intervention. After 4-6 hrs, if he's mildly groggy, confine him (to prevent accidental injury by falling off furniture, stairs, etc). It might take 24-48 h for full recovery.
If this just happened in the past hour as it sounds, you can induce him to vomit and see if he will bring it back up. To do this at home, you can give hydrogen peroxide (2 tablespoonfuls) and wait 10 minutes. If no vomiting, repeat once more. IF still no vomit, then this is not going to work. If you want to induce vomit at that point then you need to take him to be seen on emergency and the ER vet can give something more powerful to stimulate a vomit.
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