UC Davis School of Veterinary Medicine
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Avoid Snakebite during Summer Pet Outings

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School of Veterinary Medicine veterinarians tell us that snake encounters with pets are most likely to occur between late April and October. Before you venture out with pets, be prepared.  

Find out what our faculty advise about avoiding snake bites in your pets, available treatments and whether vaccination is a good option for your pets. The 2006 Pharmacy Service publication, "Management and Prevention of Rattlesnake Bites in Pets," is available as a PDF from the  William R. Pritchard Veterinary Medical Teaching Hospital.

Valerie Wiebe, PharmD, of our hospital pharmacy has reviewed this information for 2010 and provides this update: 

"The Canine Rattlesnake Vaccine (Red Rock Biologics) comprises venom components from Crotalus atrox (Western Diamondback). The vaccine became available in the early 2000s as a means of preventing morbidity and mortality in dogs likely to be bitten by rattlesnakes.  Although there may be circumstances where a rattlesnake vaccine may be potentially useful for dogs that frequently encounter rattlesnakes, there remains little fact-based data to support the efficacy of the vaccine to date. Dogs do develop neutralizing antibody titers to C. atrox venom, but titers may vary and frequent boosters (4-6 months) may be required to maintain titers.  Vaccine costs are between $20.00 to $40.00 per injection. According to the manufacturer, rare vaccinated dogs have died following a bite when there were substantial delays (12-24 hours) in seeking treatment. According to the manufacturer, no new efficacy trials have been performed to verify efficacy.

The vaccine has been administered to over 100,000 dogs to date, and appears relatively safe, with less than 1% reported side effects.  The most common side effects have included sterile abscesses (1/300 injections) and injection site reactions or lumps (1/1,500), most of which resolve without treatment in 3-4 weeks.  Flu-like symptoms have been reported in 1/3,000 vaccinations which are reported to resolve in 2-3 days.  Anaphylactic reactions are estimated to occur in 1/250,000 cases. 

Although the product is relatively safe, even vaccinated dogs bitten by rattlesnakes should be considered a veterinary emergency. This is due to the fact that 1) snake venom components vary with species and some (e.g., Mojave rattlesnake) may not be covered by the vaccine 2) antibody titers may be overwhelmed in the face of severe envenomation, and 3) an individual dog may lack protection depending on its response to the vaccine and the time elapsed since vaccination. 

Antivenin and other types of supportive care are still recommended in vaccinated dogs as there is no significant difference in the course of therapy if the animal is bitten. 

Due to the vaccine’s questionable efficacy, cost, and lack of  substantial difference in acute therapy if an animal is bitten, the vaccine is currently not stocked and is not advocated for animals routinely seen at the Veterinary Medical Teaching Hospital. For clients in high risk areas and where emergency treatment may be substantially delayed, the vaccine may buy time for the owner to seek emergency care. In these cases, owners must weigh the benefits versus the risks and be aware that the vaccine does not insure protection against the venom."

In the unlikely event of a rattlesnake bite, board-certified experts in the Emergency and Critical Care services are ready 24 hours a day to treat your pet. The hospital pharmacy carries antivenin for treatment.

Call (530) 752-1393  or, after hours, (530)  752-5438.

Online directions to the Veterinary Medical Teaching Hospital.