"All we can really do is HOPE that animals can't become zombies. Otherwise birds would be a huge problem.

"

"and mosquitos, those are my worst fear if they carry them then we have a huge problem"

"If you have a horse in your fortress common cents tells me that you would keep it in a pen or other room. At least you would tie it up so it isn't wandering around and destroying your supplies. You would also not want it Shitting and Pissing all over your fortress. And you can't teach a horse to go in a certain place.

There's no way I would keep a horse or any animal ( except a dog or cat ), and not have it secured in a designated area. "

"I would think hobbling a horse would limit its usefulness, but I readily admit I know little about horses.
If you do need horses in your fortress, I suppose the solution would be to keep them secured so if they do get infected they can't just wander about and 'nibble' on whoever they come across. DaveBall's comments on the sh!t and piss dictate common sense would keep a horse in seperate quarters from you anyway."