With  recent studies  showing that pets' bellies are growing faster than ever, owners may be contributing to their pets' obesity without even knowing it, according to The Associated Press .

Owners can overfeed their animals by as much as 25% a day, said  Ernie Ward , a veterinarian and founder of the  Association of Pet Obesity Prevention . "It seems so innocent. You overfeed and you don't even know it," he said.

However, Ward doesn't place the blame on petfood, but on treats, calling them "kibble crack" and "calorie grenades."

Marion Nestle, a professor and co-author of  Feed Your Pet Right , agreed with Ward, saying the worst offense may be the "guilt treat" - those dropped by the handful when pets have to be left alone.