Rattlesnake Bite

Just over a week ago Highboy was bitten by a rattlesnake.  Because I know we have these snakes in our area, when the vaccine for bites was introduced in the veterinary community I had all my horses and dogs vaccinated.

Everyone here has been vaccinated for 6 years, and no one here has ever had a vaccine reaction.  The first time a horse is vaccinated it's an intramuscular injection in the pectoral muscles of the chest, and they get a booster one month later.  After that the vet gives them boosters annually in the spring as the snakes are starting to come out of winter hibernation.  The vaccine stimulates the body to create an immune response to the venom because it recognizes it as a threat.  If the horse is bit later and venom injected into the body, the white blood cells will recognize it from having "seen" it before in the vaccine.  The body can then launch an attack on the venom and destroy it before it can do too much damage to the animal.

We suspect that the snake came out  in the warm weather, then when it rained and snowed again it probably took shelter in Highboy's hay.  He may have gone to get something to eat and the snake bit him then.  Highboy was fine on Sunday morning when he ate his mash for breakfast, but when I went out to ride him an hour later his nose was swollen and he had a large wound that looked necrotic. 

 However, because Highboy was vaccinated he didn't have a systemic reaction.  Yes, his nose swelled up, but normally a horse bitten by a rattlesnake will have many more issues.  The entire face will swell, and even through the neck will get quite large.  The horse will usually run a fever, they can have tremors, difficulty breathing, increased heart rate and lethargy.  Highboy had none of these. 

One of my geldings who was not vaccinated, Samson, was bitten a couple years ago.  It was the most venom my vet and CSU had ever seen injected into a horse. His face swelled up until he looked like a hamster and I couldn't even get a rope halter on him because it was so large.  I had to create a makeshift halter using a very soft rope so that I could handle him.  As his difficulty breathing gradually increased it became clear he wasn't going to survive, so we euthanized him to spare him the ordeal of dying painfully from the rattlesnake bite. 

I'm convinced that with the size of the wound and how much tissue died and sloughed off, Highboy he must have also been hit by a significant amount of venom.  There's no way to know if it was the same snake of course, but I'm so grateful Highboy had the vaccine and that he had such a minimal response to the venom.  Just one week later his nose's size is totally back to normal, and the areas where the tissue was destroyed are coming back with healthy pink granulation tissue.  He has been in good spirits this entire time, and eating well through the whole process.  He is one lucky horse.

Big thanks to Dr. Landes with Equine Medical Services for administering these rattlesnake vaccines for us, and for being so supportive through Highboy's ordeal.