Snakebite!

As an equine veterinarian, I tend to think there are only a few true emergencies we see with horses. For example, some colics are true emergencies based on the need for surgery, a few types of lacerations, dystocias, castrations (my personal favorite), and snakebites. With the temperature staying well over 100 F in the summer months, the likelihood of venomous snakes being active and aggressive goes up also. So, if you are new to horses or just haven’t yet seen a snakebit horse, there are a few things you should prepare yourself for besides the amazement of just how big a horse’s head can swell up.

For the most part, Diamondback rattlesnakes are the primary cause of venomous snakebites in the Southwestern U.S., with Copperheads and Moccasins coming in a distant second and third, respectively. The type of snake, in my opinion, is not as important as the severity of the bite. The only time I have actually seen the snake that bit the horse I was called to look at it was still in the stall when I went in to examine it! No one bothered to check that out before calling me, and I have since learned my lesson. That being said, I’m sure young, small snakesbite as many horses as large, older ones do. But based off human medicine where most snakes are positively identified, there is some variance in the severity of the bite based solely on how much venom was injected by the snake, not the size.

Since horses do not get bit at the vet clinic, here are a few things you should have thought out and prepared for in the unfortunate case your horse is bitten. Almost all snakebites with horses occur on their nose, and subsequently the most immediate complication becomes whether or not the nasal passages swell shut. Horses cannot breathe well through their mouths alone, and if you ever see one doing it they are fixing to die, so remember that. As bad as snake venom is, it is rarely fatal in horses due to the relative proportions of venom versus the size. Therefore, the most important thing you can do is to maintain a good airway through the nostrils to prevent your horse from suffocating before emergency treatment can be started by a veterinarian. Any way you can do this is the right way. Cut off pieces of garden hoses, syringe cases, or anything else you can find that is round and about 1 inch in diameter and about 5-6 inches long. The horse may not appreciate it at the time, but having sections of tubing stuck up his nose will save his life. Step 2 is to get some type of anti-inflammatory in them. Most horsemen will have Banamine® handy and the real cool ones will have some dexamethasone also. Giving one or both of them as soon as possible will not reverse the toxin, but will mitigate some effects of it.

Step 3 is to get your horse to the vet ASAP. Depending on the amount of facial swelling and whether or not the horse can effectively breathe through their nostrils will determine if an emergency tracheotomy is needed to by-pass the obstructed airway. Human snakebites are routinely treated with anti-venom, but in horses it is extremely expensive due to the size difference, and does not affect the outcome of the case. Therefore, I do not tend to use it. I do routinely perform complete blood counts (CBC) on these horses to assess hydration status as many of them have facial swelling so severe that it prevents them from being able to drink or eat.  The worst ones stay on IV fluids for several days till the swelling goes down enough to allow them to eat and drink semi-normal.  Broad spectrum antibiotics, anti-inflammatories (steroids and NSAIDS), and good nursing care return these horse back to normal. Facial swelling may take up to two weeks to resolve, and in a few cases tissue around the actual bite location may slough out and require more wound care. Be sure to have another CBC and full chemistry panel run on your horse about 3-4 weeks after to check for potential liver or kidney problems that can come from delayed toxicities related to the bite. In the rare, and very unfortunate event your horse is bitten on the leg, or abdomen do everything you can to get your horse to a veterinary hospital as fast as you can. These are the worst of the worst and require attention well beyond the scope of this article.

Hopefully, you will never have to deal with a snakebit horse, but if you do, it is a true emergency. Be prepared with at least the knowledge of what to do and where to go.  If you’re like me, it may have to wait till you get done screaming like a schoolgirl after you’ve seen a snake, but that usually doesn’t take very long.