Vaccine Effectiveness, Limitations, and Cross Protection
How well does Rattlesnake Vaccine actually work? First let’s discuss the theory of the vaccine. We have been around rattlesnakes and dogs for a long time; so much so that the rattlesnake used to be a symbol of the United States. People have long observed that dogs can develop an immunity to rattlesnake venom. They just need to survive being bitten a few times first. This is because animals have immune systems that are able to create antibodies to many types of infections and toxins.
Rattlesnake Vaccine stimulates a similar immune response in dogs to produce these protective antibodies. These antibodies create measurable levels of protection and have been shown in the laboratory to have a very similar effect to antivenin at being able to bind to and neutralize the proteins in rattlesnake venom. So the theory works in the laboratory, but how well does the vaccine actually work in veterinary clinics?
In 2006 there was a nationwide survey of 720 veterinary hospitals that carried the Rattlesnake Vaccine that showed that about 30% of them had already treated vaccinated dogs for rattlesnake bites. These clinics were asked to rate how well the vaccine worked and give specifics on how vaccinated dogs did as opposed to non-vaccinated dogs who were bitten by rattlesnakes.
Just over 90% of veterinarians and animal hospitals rated the vaccine as working either well or very well. About 5% said that they had mixed results; sometimes the dogs appeared to do much better than would be expected and sometimes the dogs did just as poorly as if they were not protected. About 3% of clinics said that they couldn’t tell if the vaccine made any difference at all. About 2% responded by saying that they wanted to reserve judgment until they had treated more vaccinated dogs for snake bite. So the result is that the vast majority of veterinary hospitals actually treating dogs for snakebite found obvious benefits from the vaccine. It is significant to note that this was a nationwide survey so it strongly suggests the vaccine is effective against a very wide variety of rattlesnake species.
These veterinarians reported benefits that included: a delay in onset of symptoms, fewer symptoms, less severe symptoms, a decrease in mortality rate, faster recovery times, and little or no tissue necrosis. Veterinarians also reported less painful dogs, less lethargy, less swelling, that the swelling progression typically reversed within the first 1 to 2 hours, and that dogs had full recoveries in about 24 to 48 hours.
The protection level that a dog receives from the vaccine depends upon how well that individual dog produces these specific antibodies and may vary. Almost no vaccine is effective 100% of the time. There are undoubtedly some dogs who’s immune systems just won’t produce as many antibodies necessary for maximum protection but the partial protection they receive may still be enough to save their lives or help them recover more quickly.
When will this vaccine be less effective? Probably the most common reason for the vaccine to not work as well as it is expected to, is that dogs are not up to date on their boosters. Regular boosters are absolutely necessary to keep up protection. This is because this vaccine is designed to fight off an intoxication, rather than infection, and there is an important difference. To fight off an infection, a dog typically only needs a compliment of memory cells ready to start producing antibodies when infection starts to happen. To fight of a sudden intoxication like a rattlesnake bite, a dog will need to have enough antibodies already produced.
Even good antibody protection can be overcome in special snakebite circumstances. But what are those circumstances? Special snakebite circumstances include smaller dogs, larger snakes, multiple snake bites to the same dog, and bites near vital organs. Smaller dogs are always going to have a harder time fighting off the same amount of venom as larger dogs. Larger snakes can produce and deliver larger doses of venom in a single bite. Multiple snake bites to the same dog can naturally deliver larger quantities of venom. Bites near vital organs allow the venom to start destroying those organs before the antibodies in the dog’s blood plasma have time to find and neutralize the harmful proteins in the rattlesnake venom. Other special circumstances may include some dogs who’s immune systems just don’t produce enough antibodies, intravenous bites, and some snake species that the vaccine has little or no protection against.
What snake species will this rattlesnake vaccine protect against? The official answer is that Red Rock Rattlesnake Vaccine is conditionally licensed for use against Western Diamondback rattlesnakes. But most of the 15 species of rattlesnakes in the United States have fairly similar venom. This is how one antivenin is able to cross-protect against so many rattlesnake species. The protection afforded by the vaccine depends on the similarity of snake venoms to the Western Diamondback. Red Rock Rattlesnake Vaccine was designed to offer the best cross protection against those snakes responsible for the vast majority of venomous snake bites in the United States.
The Vaccine offers the best protection against the western diamondback rattlesnake. As an off label use, the vaccine has been reported to have good protection against the western rattlesnake (which includes the prairie rattlesnake and seven other sub-species common in the Western United States). From the hundreds of snakebite reports to Red Rock Biologics from across the country, the vaccine is also reputed to have some protection against the pigmy rattlesnake, massasauga rattlesnake, timber rattlesnake, and copperheads. Red Rock Biologics has determined that the vaccine gives little protection against the eastern diamondback and no protection against the Mojave rattlesnake, coral snakes, or cottonmouth snakes.