A guy takes his dog to the vet...
 

A man takes his collie to the vet for his annual checkup.

The vet picks up the dog and looks into his eyes for a minute. Then he just gives the dog a kiss on the nose. He says to the man, "I'll go ahead start his checkup, but I'm afraid I'm going to have to put your dog down."

"Why?" the man demands, shocked.

Placing the dog on back on the floor, the vet replies, "Because he's really heavy."

hehe...