I believe this hunter's story completely.
About ten years ago, I bagged a bobcat with a single 20Ga. slug at ~50 yards (one shot was fatal, but I followed up with the other two just for good measure). We had been losing goats for quite some time, so I went up in the pasture to look for remains to try to find out what was doing it (the question was whether it was 2 or 4 legged predators doing the killin'). I encountered a VERY unhappy looking bobcat, which is exceptionally strange because they generally avoid humans that close to our fires, trucks, tractors, and other assorted things that make smoke and noise (less than 300 yards from the pole barn). He made what, in my opinion, was an aggressive move, so I shot the little bugger and called out the game warden.
The warden said that the cat behaved aggressively, and that I killed him within less than 200 yards of the goats' feeding area after we had lost several, so I acted in defense of my person and my livestock. No problem, please sign at the X, and he sacked the animal up and sent him off to the lab. The animal turned out to be rabid, and was not the first wild predator we had killed in that pasture that tested positive for rabies. This sort of information is invaluable to wildlife management and agricultural types, as a rabies outbreak threatens all sorts of hunting and agricultural activities. I have never killed an animal I didn't have to, and I have always called the game warden when circumstances warrant.
It was feral dogs, not wild ones that had been eating my goats. Grandad took care of five or six of them in about three seconds with a Garand. Freakishly good shot, he is.
AZLib, as for the bit you found with the mule... I'm inclined to believe it. We bought a donkey shortly after we dealt with the dog problem for just that reason. She wouldn't bother my beagle, who was friendly enough to mingle with the goats anyway, but we had several other, much larger, dogs who she would angrily chase out of the pasture. I don't know much about donkey psychology, but she sure looked angry enough to kill those dogs.