I brought my 16 week old am. bull to a friends house. He was happy jumpy when I got there. we let he and their dog outside. their dog came back to the door. my dog lingered behind and came inside. he was calmer and started coughing ,then he threw up the contents of his stomach in a white base. then he kept trying to throw up. I brought him home he became lethargic and would not eat or drink. he has since calmed down but he obviously feels bad