The dog was growling as it leaped off the Doctor, it was looking back at the Doctor and then at Caitlyn. The dog growled more is looking ready to attack again. Jack rushed to the Doctor's side and tried to at least stop the bleeding and make sure he was ok.
The Doctor groaned and was in pain, He knew that he would be ok , he was determined to carry on as well.
He didn't really agree with them shooting it, but there wasn't much that could be done in this situation.