I'm in the same boat as you about the vet. Pus can form from any infection. Usually why there is pus if there is bacteria in there. The only thing that I can think of from horses and cows is hoof rot but I believe that's a fungus. If not than bacteria but chickens don't have hooves and I don't think horses and cows get bumble foot. I can't really think of a disease they all share off the top of my head. What did he do with the q-tip? If he threw it away right a way I would probably call him on it. Cancer is do to abnormal cellular growth. Wonder what he meant by duct. I would give him the antibiotic, really like nothing bad could come from the antibiotic right now. Syringe feed him and maybe give him some electrolytes in his water. I honestly don't know what else you could try. Electrolytes might give him some energy to try to fight the infection with the antibiotic. In all honesty though I would call the vet on his stuff. Antibiotics wouldn't really help with cancer. Antibiotics are more for bacteria or a virus. Also this vet must have never worked with a cow with an abscess. They can be as hard as a rock and smell terrible and can be a little gross when you rupture them. Also I can't think of a foot bacteria that comes from both livestock and poultry off the top of my head. This vet sets off a few red flags in my opinion.I messaged a friend about bird vets and she referred me to one so I drove almost two hours yesterday, the vet walked in poked the roof of his mouth with a q-tip and said it was much to firm of a growth to be any kind of abcess or infection. He said what he had was almost like a cancer, it was caused by an bacteria that comes off of the feet of livestock and cows horses and chickens can also get the bacteria but it effects them all different. He said the bulge on the side of the face was most likely a blocked duct caused by the growth. He gave me an antibiotic and said he has about a 10% chance of survival because the growth will inhibit is ability to eat and not go away probably and left. It makes sense with the growth but I only 50% believe him. Why would a growth caused by bacteria get puss all over it? Not to mention he spent 5 seconds looking at him and touched it with a q tip and left. He was only in the room for 5 minutes. So do I believe him and just give him the antibiotics and syringe feed him for a week while he dies or try getting the crap out of the side of his face and keep picking the puss off of his growth? I'm stumped and not sure who's advice to follow