Get Your Dog Care Questions Answered by Experts
If he just ate them, you can make him vomit by giving him 5 table spoons of hydrogen peroxide. Do not repeat this if it does not work as it can cause irritation to the stomach and esophagus. You can also take him to an emergency vet and they can give him an injection to make him vomit and give him activated charcoal to help absorb any that has made it passed his stomach before he vomited.
A single dose of prednisone is not likely to be life threatening unless it is very high (do you know how many pills you threw out?), however even moderate doses will run the risk of GI ulceration. To help with this, you can give him 20mg of omeprazole (over the counter) twice daily for 3-5 days. This will not prevent ulceration but may help it to heal. Does this help answer your questions tonight?
The safest thing to do would be to take him in and make him vomit then give him activated charcoal, however barring this, follow the instructions above about omeprazole and monitor him for black tarry stool, vomiting, or lethargy. If he experiences any of these, he needs to be seen by a veterinarian.
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