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Ask the Vet: Rattlesnakes by Kristel Weaver, DVM, MPVM
May 2, 2020

Last spring I was on a hike with my dog and we encountered a rattlesnake.  What can I do to protect my dog from rattlesnakes?  What should I do if a rattlesnake bites my dog?

To answer this question I’ll provide some basic background information on rattlesnakes and their bites, then discuss the rattlesnake vaccine.  

About rattlesnakes

Rattlesnakes are most frequently encountered between April and October and are most active in the spring when they come out of hibernation. They are not overly aggressive towards dogs or people, but will strike out when provoked as a defense mechanism. In Northern California we have one type of rattlesnake, the Northern Pacific Rattlesnake. 

What happens if my dog is bitten?         

The site around the bite wound swells up quickly as the venom causes severe damage to skin, muscle, and nerves. Once the venom gets into the blood stream it can lead to problems with blood clotting and cause damage to internal organs. Rattlesnake bites can cause death. Approximately 20-25% of rattlesnake bites are “dry” which means that no venom is injected with the bite, but you can’t easily tell if your dog received a “dry” bite or one with venom.

Rattlesnake bites can cause severe swelling.

Rattlesnake bites look like two parallel wounds that may or may not bleed. Dogs are most frequently bitten on their face, neck or extremities. Venomous snake bites can cause extreme pain, swelling, cell death (tissue necrosis), clotting problems, and infection. Often, many dogs we see that have been bitten by a rattlesnake end up being hospitalized for a day or two and on some form of morphine because of the extreme pain. If you think a rattlesnake has bitten your dog, seek veterinary care as soon as possible. 

The good news - a vaccine!          

There is a vaccine for dogs against rattlesnake venom. The vaccine stimulates the dog’s immune system to make antibodies against the venom so that, if bitten, the dog will have a less severe reaction to the venom. Possible side effects from the vaccine include a lump at the site of vaccination that goes away after a few weeks, flu-like symptoms or an allergic reaction.  The vaccine is not made specifically for the Northern Pacific Rattlesnake, but is still thought to provide protection if bitten because of similarities between the venoms.

Should my dog get this vaccine?

This is NOT a core vaccine recommended for all dogs.  This vaccine is recommended for dogs that may encounter a rattlesnake.  For example dogs that have rattlesnakes in their yard/environment or dogs that go hiking, hunting, or camping are good candidates for this vaccine.  The first year that a dog is vaccinated against rattlesnake venom it requires two vaccinations 3 to 4 weeks apart.  After that first year, dogs get a booster once a year in the spring. The vaccine gives a dog’s immune system an enormous head-start in responding to and protecting a dog from the harmful effects of rattlesnake venom. However, it is still recommended that any dog bitten by a rattlesnake, even if vaccinated, be brought to a veterinary hospital immediately. Further treatment, although abbreviated and far less costly than would otherwise be needed if a dog weren’t already immunized, is still required for some dogs that have been bitten.

Tips to avoid rattlesnake bites

  • Never wear sandals when walking in wild areas.
  • Keep your dog on a leash while hiking.
  • Do not allow your dog to explore holes or under logs.
  • Avoid tall grass, weeds or underbrush where the snakes may hide.
  • Step on large logs and rocks, not over them, to see what is on the other side.
  • Don’t grab “sticks” or “braches” floating in the water; rattlesnakes can swim.
  • Never hike alone, in case of an emergency.
  • Do not handle a freshly killed snake -- the fangs can still be venomous.

Dr. Kristel Weaver is a graduate of the Veterinary School at the University of California, Davis where she received both a DVM and a Master’s of Preventative Veterinary Medicine (MPVM).  She has been at Bishop Ranch Veterinary Center & Urgent Care in San Ramon since 2007.  She currently lives in the Bay Area with her husband and their two children.


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