Rattlesnake Bites In Horses – What Every Horse Owner Needs To Know

by Lisa Carter on April 6, 2012

Rattlesnake season is again upon us in the state of Texas.  The warm spring weather has awakened the slumbering reptiles from there winter hibernation.  We've already seen several dogs and cats at our vet clinic arrive with swollen heads or limbs.  You can't help but feel sorry for them as they suffer through the symptoms of their encounters with these highly venomous creatures.  Rattlesnake bites in horses are very dangerous and a pretty common occurrance.  Knowing what to do if your horse is unfortunate enough to have a run-in with a rattlesnake can make a huge difference in the recovery time and the extent of the tissue damage caused by the rattlesnake venom. 

Most Common Bite Locations On The Horse and Associated Complications

rattlesnake "dry" bite in horseThe majority of rattlesnake bites in horses occur on the nose.  Horses by nature are very curious animals, and during grazing come into contact with the snakes.  The rattlesnake's characteristic warning rattle draws the curious horse's in and they can't help but to go investigate the coiled up critter making the noise. 

Horses bitten on the nose do fairly well as long as their airways do not become compromised.  Their heads can swell quite dramatically and the nasal passages can close off.  If this happens, tubes will need to be placed in the nostrils to allow the horse to breath.  Horses with bites to the head can also have problems with food intake due to the pain and swelling associated with the rattlesnake bite and may need alternative means of getting nutrients. 

The next most likely place for your horse to get bitten is on the legs.  As with humans, horses can walk by completely unaware of snakes hidden in the tall grass, brush piles or under rocks and logs and will get within striking distance without even knowing until it is too late.  These types of bites can be the worst, as the swelling in the limb can cut off blood supply to the hoof.  In effect, the horse develops laminitis.  In severe cases life threatening complications can occur, particularly if the rattlesnake's fangs puncture a joint, usually just above the hairline and hoof wall junction. 

What Should You Do If Your Horse Is Bitten By A Rattlesnake?

Despite all the old western movies depicting snakebite victims having the poison sucked out of their wounds, this is not the recommended first response treatment!  Do not attempt to open the puncture wounds or suck the venom from your horse.  You risk your own health and further contaminating the wound site by doing that. 

If your horse is bitten by a rattlesnake, contact your veterinarian as soon as possible.  Keep the horse calm and confine its movements as much as possible, as increased heart rate and respiration can help spread the venom through the tissues even faster.  If you have a good relationship with your veterinarian, they can help you put together some first aide supplies to keep on hand that will help buy you some time in case you can't get to the vet quickly.  Giving an anti-inflammatory drug like Banamine or bute can help with the pain and swelling.  Most horse owners have one or both of these drugs available either in the barn, or if traveling, in the tack room of their trailer. 

Most treatment plans will include a course of antibiotics, as risk of secondary infection is high with rattlesnake bites.  The antibiotic of choice is usually penicillin.  However, penicillin is notoriously under dosed by horse owners that take it upon themselves to treat their horses without consultation with their veterinarian.  The correct dose for an average 1000-pound horse is 30 cc intramuscular twice daily.  When administering penicillin injections to your horse, you will want to make sure and rotate the injection site each time to minimize the soreness, alternating between the large gluteal muscles of the rump and the trapezius muscles of the neck.  Do not attempt to give the injections yourself unless you are confident that your horse can handle them.  Some owners have found out the hard way with a well-placed kick that their horses were not tolerant of the painful injections.  Depending on the severity of the bite, your veterinarian may also want to administer a corticosteroid and/or intravenous fluids. 

Within a short time of being bitten, swelling will start to appear around the bite area as the venom invades the surrounding tissues.  Rattlesnake venom works by breaking down the tissues, in effect digesting the tissues.  Excess fluids from this breakdown process will quickly begin draining from the bite area.  Sometimes they find their way out in the general vicinity of the bite wound, but will generally rely on gravity to find the best exit from the body.  You can expect in most cases for these symptoms to begin to subside within the week.  Within a few days of the cessation of drainage, the skin will usually start sloughing from around the area of the bite.  Due to the risk of secondary infection, it is important to keep the area clean, keeping in mind that the area will be extremely painful to the touch.  Warm, soapy water or a mild antiseptic solution should be sufficient to wash the area. 

Last fall was the first time I had to deal with a rattlesnake bite on one of my horses first hand.  He was bitten right on the end of the nose, below the nostril.  The fang marks were approximately 1 inch apart, so it was a fairly large rattlesnake.  We were lucky in that the bite was a "dry bite" in which the snake did not envenomate.  This happens in approximately 50 percent of rattlesnake bite cases.  The snake either has exhausted its supply of venom on a recent meal or is startled and just bites in warning without envenomating.  My horse did have some minor swelling for several days and sloughing of the skin about 4 or 5 days after the bite.  I had anti-inflammatories and antihistamine in the barn and was able to administer those immediately.  I was thankful that I had those supplies already on hand and did not have to wait to start treatment until I could either get my horse to town or get my vet out to my house.  Most veterinarians are happy to walk you through what you need to do as a first response over the phone if you have the necessary medications and supplies at home. 

As with medical emergency, symptoms and treatments will vary from case to case.  Always consult with your veterinarian before starting any treatment plan.  Do not wait until it is a life-threatening scenario before you call.  The old saying, "the best defense is a good offense" is really quite true.  Talk to your veterinarian now, before the emergency arrives, about what kinds of supplies you should have on hand and arm yourself with knowledge.  You are your horse's first line of defense in all things.  


Lisa Carter is a Certified Equine Massage Therapist (CEMT), with multiple certifications from several different equine bodywork schools.  She incorporates her knowledge and experience with Parelli Natural Horsemanship, equine bodywork and as a veterinary technician to provide her clients with the resources they need to make informed decisions for their horses.  She encourages and facilitates network building between equine health care professionals, working together to find the best combination of therapies to meet the needs of the "whole horse".  

Are you ready to get better results with your horse?  Put your equine health care team to work so you and your horse can be doing what you were meant to.  Click here to get started!

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Boni Demaree April 29, 2012 at 5:10 pm

Thank you. Great information to have.

Renee July 10, 2014 at 8:22 am

Had this happen to my mare about 10 years ago, but couldn't find the bite mark. she is now 22 years old.

Lisa Carter Lisa Carter July 10, 2014 at 8:04 pm

So glad it turned out okay in the end 🙂


Kathy July 7, 2015 at 10:56 am

One of my horses was bit by a snake last fall, we are thinking water mocassin but not for sure.  Her reaction was much worse that what you described for your horse.  She was bit on the side of an upper lip; at first I just thought it was a hornet sting because I could only find one spot.  She spent at least 21 days on Benadryl, twice a day, was given a steroid shot and sloughed off the skin on all of her face, her neck, most of her chest and from her hip bones down her back legs.  It was quite the ordeal!  Now, nearly 10 months later it looks like she may have also lost some of her vision from it too.  She is having problems seeing things that she normally didn't have problems seeing.  The vet is going to give her a vision test a bit later in the summer. I'm just glad I found her when I did; I think less than 30 minutes after the bit occured. 

Lisa Carter Lisa Carter July 8, 2015 at 8:10 pm

Wow, how scary!  We got really lucky with Spirit when he got bit.  The vet thinks it was a dry bite.  Speed is definitely of the essence when it comes to snake bites.  I hope that your horse continues to heal and show improvement. 



Kelli Roberson July 9, 2015 at 2:21 pm

Why did you not mention the equine rattlesnake bite vaccine?  What effect does that have on treatment after being bitten?

Lisa Carter Lisa Carter July 10, 2015 at 7:53 am

Hi Kelli,

I did actually ask the equine veterinarian at the vet clinic where I worked at the time I wrote the article about the availability of a rattlesnake vaccine for my horses and he indicated that we did not have one available to us at that time (in our area).  I can’t remember the reason why we couldn’t get it.  So I did not pursue it further and assume that other people can’t get it as well, so focused on other more commonly accessible strategies for people to do. 

In my experience with canine rattlesnake bites, dogs that have had the rattlesnake vaccine seem to have slightly less severe reactions to the bites, but still need immediate treatment by a veterinarian.  I have a friend whose dog is bitten quite a lot as they live in a heavily wooded and brushy area.  He’s had the vaccine, but still has to be hospitalized.  So in my opinion, while it can help, it is not a guarantee against serious and life threatening reactions. 



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