Is Your Pet Obese?

I have a Pug that is3 years old and weights 50 lbs and he loves to eat. I have put him on a strict diet and he lost 5 lbs and thats all. I am so worried about him and dont know what to do. The trainer at PetSmart said to feed him Blue Buffalo. I only give him 3/4 cup a day and he gets about 10 Charlee Bear treats a day. That is what she advised me to give him. I am afraid he is going to die. My son ask me if they done By-pass on dogs. I told him afraid not. Any suggestions? Please help!