One of the funny things about living in Southern California is knowing that some people won’t go hiking because they are terrified of rattlesnakes. They think as soon as they step foot onto a trail, a horde of vicious, fanged menaces are going to leap out and inject them with poison. Maybe this helps keeps the crowds limited on our beautiful outdoor spaces (except in Torrey Pines on Labor Day, my goodness!). I’m sure the same people avoid the ocean because of sharks too. However unlikely an encounter may be, some people, including our beloved Dr. Tedder, are terrified of any and all snakes, and especially ones with built-in maracas. Fear is always an effective marketing tool, and there are a number of silly “snake-proofing” products on the internet. They run the gamut from ridiculous to plausible, and one of the more interesting products available is a rattlesnake vaccine (http://www.redrockbiologics.com/) for dogs and horses. But is this vaccine a good idea? The science isn’t there to support it just yet, although it’s better than some other stuff out there. Read on pet lover, and we will hopefully shake out fact from fiction.
While encounters are rare, I have to concede that we will occasionally come across a venomous little tube of muscle undulating across the trail. It’s exciting and scary and the best option is always to be respectful and keep your distance, which makes a bite VERY unlikely. But while we bipeds may be careful and cautious, often we’re hiking with dogs who can only be described as “simple-minded”. Their eagerness to make new friends and grab things that look like sticks can certainly get them into trouble. It’s estimated that there may be more than 100,000 venomous snakebites in dogs and cats in the US each year1. Fortunately deaths are pretty rare, but treatment is almost always necessary.
If a dog is bitten by a rattlesnake, they need veterinary attention ASAP, no question. If the dose of venom is high enough, then the dog will need antivenom, which is the antidote to rattlesnake venom. Antivenom is essentially pre-made antibodies to a mixture of different rattlesnake venoms4 (more on that later, but yeah they’re not all the same type of toxins). We can inject these antibodies into the bitten patient and they soak up all of the venom, stopping it from causing harm. It tends to work really well, although multiple doses are often needed and it’s not cheap (get pet insurance!). Also, if there are any delays in treatment, the antivenom may not be enough to prevent permanent damage. Obviously the best case is to not get bit in the first place (we recommend rattlesnake avoidance training), but as we all know, sometimes stuff happens.
Which finally gets us to this rattlesnake vaccine. Is it a good idea to have your pet “immunized” against snake venom? Sounds cool, right, and the idea behind it is interesting. Here’s the concept: create antivenom in the bloodstream so that when the snake bites the dog, the antidote is already there and the venom automatically gets neutralized. This is actually exactly how antivenom works when we give it. When a snake puts venom in a dog (bad), a veterinarian can inject antivenom (good) to stop the venom from doing bad things. So wouldn’t it be great to just have the antivenom in there in the first place?
Maybe a little Old West analogy will help. Let’s say there’s a bad guy in town, and we don’t know when he’s gonna show up and get to causin’ trouble (please continue to read in a Sam Elliot voice). The town is the body, and the bad guy is the venom. Think of a vaccine as a way for us to tell the body to target that bad guy before he gets there, like a “Wanted” poster that gets everybody in town on alert. In theory, the antibodies (townspeople) will jump on the venom as soon as it hits the body. If there’s enough of them, they’ll rangle him up and lock him in jail, and nobody gets hurt (ok you can stop the fun voice if you want to).
Like I said, it’s a very interesting theory, and in fact some squirrel species are naturally resistant to rattlesnake venom2 (how cool is that!). So we can basically make your dog immune to the venom, right?
Here’s the big problem with the vaccine: we don’t know if it works. Kind of a tough sell, right? We know that it could, maybe, possibly, under-the-right-circumstances, work. But there are actually quite a few leaps of faith to we’d need to make to trust it. To stretch our Old West analogy further, let’s consider what we know about this vaccine. We know that the vaccine does post wanted posters (i.e. it makes the immune system create antibodies) and we know that it riles the townspeople up and that they do react when they see the bad guy (i.e. the antibodies react with and neutralize the venom). This all sounds good until we dig a little deeper and ask a few important questions. Here’s when we should be double thinking that leap. Ready for some monkey wrenches in the plan?
- What if it’s not the right bad guy who’s causing a ruckus?
There are about 40 different species of rattlesnake species (we have four species in our county5) and the vaccine only produces neutralizing antibodies to one of them for sure. It might have some effect on other venoms, but we really don’t have any idea. Are you a good enough herpetologist to know which snake bit your pet?
- How long do those “Wanted” posters stay up for?
If they get taken down after a week of not seeing our villain, how riled up are the townspeople gonna be? As of right now we have no idea, meaning, we have no idea how long a dog might actually benefit from this vaccine and when to give boosters.
- How many bad guys are gonna show up?
If it’s just one troublemaker, the small town posse could probably handle him. But what if there’s a whole gang of them? We often don’t know how much venom is injected, and we don’t know how many antibodies are produced, so if our math is off by even a little bit, the antibodies can be overwhelmed.
Could it work? Yeah. However, there are some “buts”, and those are big “buts”. I would not trust it to save my dog’s life. Even if a dog had been given this vaccine, that pet owner would need to react exactly the same way if their dog does get bitten, which means they need to get them a veterinarian with antivenom right away. In a recent study3, dogs that had been vaccinated did no better than dogs who hadn’t been vaccinated. If you really want a pet that’s immune to rattlesnake venom, adopt a ground squirrel, or learn this move (don’t do either of those please).
Written (and external links inserted) by:
Greg Bishop, DVM
- Armentano RA, Schaer M. Overview and controversies in the medical management of pit viper envenomation in the dog. Journal of Veterinary Emergency and Critical Care. 2011 Oct 1;21(5):461-70.
- Biardi JE, Chien DC, Coss RG. California ground squirrel (Spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins. Journal of chemical ecology. 2005 Nov 1;31(11):2501-18.
- Cates CC, Valore EV, Couto MA, Lawson GW, McCabe JG. Comparison of the protective effect of a commercially available western diamondback rattlesnake toxoid vaccine for dogs against envenomation of mice with western diamondback rattlesnake (Crotalus atrox), northern Pacific rattlesnake (Crotalus oreganus oreganus), and southern Pacific rattlesnake (Crotalus oreganus helleri) venom. American journal of veterinary research. 2015 Mar;76(3):272-9.