Why is my dog retching or gagging?

Common reasons a dog vomits include eating too much, physiological vomiting, eating the wrong thing, internal parasites, and gastrointestinal problems. Eating until overly full burdens the dog’s intestines and easily causes vomiting.

Some dogs vomit up freshly eaten food and then eat it again; this is physiological vomiting and the owner need not worry.

Also, if the dog ate unclean or spoiled food, vomiting often follows. If the dog also has diarrhea or lethargy, take it to a veterinary hospital promptly.