Welcome! I am Dr. Altman, a licensed veterinarian and happy to answer your questions today.
May I ask what mg the tablet was?
Ok. Vomiting can occur at 0.01 mg/kg which is 0.06 mg for your dog and tremors, ataxia and tachycardia at 0.06 mg/kg (which is 0.38 mg for your dog)
Since this just happened I would strongly advise you to induce vomiting for Shadow. If you have 3% hydrogen peroxide go ahead and give her 1 & 1/2 tsp of hydrogen peroxide then walk her around or "giggle" her belly to mix the peroxide in her stomach which will agitate the lining and induce vomiting. This can be repeated once at 10-15 minutes if there is no vomiting seen
I am going to change formats in a moment to ensure you are not having difficulties with live chat and can view my responses readily. You both are in my thoughts and please don't hesitate to let me know if you have any additional questions I can assist with