Q: Have you noticed or had owners comment on the change in a horse's personality after a rattlesnake bite? My mare was bitten on the muzzle six years ago. We almost lost her, but after two days of treatment with various medications she survived. However, her personality seemed to change. She seems less people-friendly and less energetic. And, most notably, she went from an easy keeper to harder to keep weight on.

I wonder if it's from some sort of facial nerve damage from the bite? My vet said many horses that have been bitten by rattlesnakes show signs of congestive heart failure when necropsied years later. Have you ever heard of these long-term effects from a snake bite? What could be going on here?

Fiona, via e-mail

A: In the United States several hundred horses are bitten by poisonous snakes each year. Of these, it is estimated that 10-30% of snake bites result in fatalities. Rattlesnakes are responsible for most of the envenomations and for almost all snake-related deaths