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Snakebit: Rattler vaccine

4/21/2005

For those of us who list turkey as one of the fowl we hunt, now is the time of year to begin thinking about snakes again. Of course, the danger of envenomation by belly-crawling reptiles applies not only to us but to dogs as well.

Every year many a good dog is lost to snakebite envenomation, but the good news is that there is a new piece of armor against one of your dog's most vile enemies. Red Rock Biologics, based in California, has manufactured a vaccine that should help protect dogs against the effects of rattlesnake envenomation.

This is good news for hunters that frequent areas with high populations of rattlers.
Historically, the best treatment for a dog that was bitten by a rattler was to use anti-venom to counterattack and neutralize the venom, but that approach was (and still is) not without its problems.

One such issue was the cost of anti-venom. At costs as high as several hundred dollars per dose, anti-venom was sometimes priced out as a treatment option. Also, because of the expense and the relatively low case rate for many veterinary hospitals, keeping a standing supply of anti-venom on hand in many areas has simply not been cost effective.

The result was that if a snakebite case was presented, either another source of anti-venom had to be found (such as a local human hospital — which do not always have it either), or treatments were limited to simply dealing with envenomation after effects.

Another complicating factor in dog snakebites is that, unless the event is actually witnessed by the owner, knowing what kind of snake was responsible is usually impossible.
Since anti-venom is made from hyper-immunized horse serum, there is a significant risk of an anaphylactic reaction from the product when given to animals other than horses.

While anti-venom is effective for most pit-vipers, in cases when the cause of swelling (snakebite, spider bite, trauma, etc) or type of snake (pit viper vs. coral snakes) is unknown, it could be deadly to give anti-venom (prophylactic treatment with anti-venom is not recommended by the manufacture). To underscore this risk, some reports indicate that 20% and up of bites from pit-vipers are "dry" bites, in which no venom is injected.

In light of all this, one advantage to using the new rattlesnake vaccine is that it won't matter if anti-venom is available or if you know for sure that your dog was bitten by a snake. The immune system of a properly vaccinated dog should be prepared to begin working to neutralize rattlesnake venom very soon after a bite.

Even though this should contribute to reducing damage from the snake's venom, for many reasons it is still best to get your dog to a veterinarian as soon as possible. These reasons include: envenomation by a poisonous snake other than a rattlesnake (or if you don't know for sure), bites that are very close to the head, artery/vein, or other area of large blood supply, and/or bites from very large snakes (which can inject very large doses of venom).

Another reason not to put all your eggs in this one basket is that the vaccine does not protect against all rattlesnakes. Currently the vaccine is based on the venom of the Western Diamondback rattlesnake. According to the manufacture, the vaccine will provide some cross protection for sidewinder, South western speckled, and Southern Pacific rattlesnakes, but not for the Mojave green or the Eastern Diamondback rattlesnake. In addition to this, despite some reports, the vaccine is also not effective against cottonmouths (also known as water-moccasins).

Still, at around 20 bucks a dose, if you live west of the Mississippi River and encounter many ratters in your hunting area it is probably a good idea to consider vaccinating your dogs. Just remember, the vaccine should be ONE part of your dog's defense against snakebites. Proper training, wise handling, and immediate care if a bite occurs are all still necessary.