I was reading an article on the diet and exercise program Bert and Ernie have been on while at the vet yesterday (Kitteh's vaccination). They were so unfit they were out of breath after 30 steps, and couldn't walk up the single step to the kennels because their bodies were so big. Apparently you can indeed love your pets too much.
In July 2008, these two Jack Russell terriers were surrendered to the Auckland NZSPCA, morbidly obese due to poor diet and lack of exercise. This is the blog documenting their tremendous weight loss.