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New Rattlesnake Vaccine For Dogs

Red Rock Biologics of Sacramento, Calif., has recently produced a vaccine to help prevent the anaphylactic (allergic) reaction of dogs to rattlesnake venom. Those of us who hike the trails and terrain of Southern Utah with our dogs will breathe a little easier with the use of this new product.

What is the vaccine made from?

The vaccine is made from the venom of the rattlesnake and is called a "Crotalus atrox toxoid." It is manufactured from the inactivated Crotalus atrox venom’s protein components combined with an aluminum hydroxide adjuvant (a chemical that makes the product more able to stimulate an immune response in the dog and binds the venom components to the tissues at the injection site, so there won’t be a whole-body dispersion of the venom as with a natural bite). The antibodies elicited by the vaccine are cross-protective against the venoms of other types of rattlesnakes found in the United States. It is labeled against the venom of the Western Diamondback Rattlesnake.

So what does the vaccine do?

First, you must realize that the vaccine does not prevent the dog from approaching, challenging, biting, attacking or in any other way making contact with the rattlesnake! (That would be too much to ask. This behavior can only be changed by training the dog to avoid the snake.) The purpose of the vaccine is to prevent the allergic reaction to the venom of the rattlesnake. It will not prevent an infection, local tissue reaction, or systemic infection. If the dog is bitten, after the dog has had the appropriate series of vaccines, then it is expected that the dog will only have to deal with the toxic effect of the venom and its damage to the tissues around the bite site. It should still be considered an emergency, and the dog should be taken to your veterinarian or the local veterinary emergency clinic, which is being organized now and will hopefully be open by April 1.

After the snakebite, the vaccine-elicited antibody will combine with the injected venom to slow down systemic absorption, neutralize toxin activity, and thereby, lessen tissue injury and pain. What should I expect if my vaccinated dog is bitten by a rattlesnake?

According to the Red Rock Biologics’ product information sheets, "The severity of a rattlesnake envenomation (venom-injecting bite) is related to the species of rattlesnake involved, the amount of venom injected, the rate at which the venom reaches systemic circulation, and the size of the dog. In unvaccinated dogs, approximately 20 to 25 percent of venomous snakebites are "dry" bites – no venom is injected. An additional 30 to 40 percent of bites are classified as "mild," reflecting minimal envenomation: pain and swelling are present, but there is little or no systemic (whole body) involvement. Another 30 to 40 percent of bites are "moderate" to "severe," reflecting increasing degrees of systemic involvement. Roughly 5 percent of envenomations are fatal," usually due to allergic reaction to the venom.

"Vaccinated dogs appear to present with fewer and less severe symptoms than similar unvaccinated dogs. Thus, in many cases, what would have been a moderate to severe bite will present as a mild envenomation, with nonprogressive swelling and little or no pain."

What if my dog has been bitten by a rattlesnake before?

This is of great concern. First, if the dog has had an anaphylactic or allergic reaction; that is, if the dog collapsed, had breathing difficulty, swelling of the face or other rapid reaction within minutes of the bite, it is not recommended that the dog be vaccinated. If the dog did not have a rapid reaction, but just had swelling and pain at the bite site, followed by infection and tissue damage, then the dog can be vaccinated against the allergic effect of the venom and benefit from the vaccine in preventing the toxic reaction and tissue damage. This is similar to people who are allergic to bee stings and have an allergic reaction to the sting, i.e. bee venom. After the first sting, the body is more likely to react more severely with each subsequent sting.

It is not known for sure how the dogs that have had allergic reactions to snake venom will react to the vaccine. They have not been included in any of the vaccine studies. My personal feelings would be to let the manufacturer perform clinical trials first, and then, if the studies support the safety of the vaccine in dogs that have previously had allergic reaction to the venom, to follow their protocol.

What procedure is needed to protect my dog?

The manufacturer has set the vaccination protocol as follows: All dogs under 100 pounds are to receive two injections, each a month apart, followed by a booster in six months in areas where snakes are out year-round. The initial series gives protection one month AFTER the last of the boosters. In areas where snakes hibernate, then the vaccination needs a booster a month prior to "snake season," in the spring. Dogs that weigh more than one hundred pounds need a third vaccine one month after the second vaccine in the initial series.

This vaccine offers hope for protection for dogs that are in high exposure activities or who live in snake-infested areas. It is a vaccine that has a potential of having reactions, especially in dogs that have already had anaphylactic reactions to snakebites before. The vaccine should only on dogs that are at high risk of exposure and should not be considered a routine vaccine for all dogs. It is a vaccine with risks, but would appear to be safe and effective by the studies that have so far been conducted.

Above all, even if the bitten dog has been vaccinated, it should still be considered an emergency, and veterinary care should be sought.

The vaccine’s purpose is to lessen snakebite reactions so that the reactions would be less severe and have a higher percentage of survival and result in a decreased rate of illness in dogs that are bitten by rattlesnakes.

By: Jean Hooks, DVM

Hurricane Valley Journal Southern Utah's News Source

See also

• Adverse Reactions To Vaccination
• The Truth About Pet Vaccinations
• Vaccine FAQ And General Information

Tags

• Pets
• Dogs
• Dog Health
• Vaccine
• Rattlesnake