Kill the dog and see if it has rabies. Doc Shelly's simple explanation makes sense.

Doc Begely: Geez… I told you! You just killed a dog for nothing! He has no rabies. He is clean. It was a farm animal.

Dr. Shelly: Err… that's weird… I was almost positive he would have rabies.

Great... you really did it this time. You should take the time to check all possibilities first before you start killing animals. By not taking the time to check all possibilities thoroughly, you've just taken the life of an innocent animal, a beloved family pet. However, it was good of you to check this possibility thoroughly.