Rattlesnakes are the only poisonous snakes found in California. The rattlesnake in our area, the Southern Pacific Rattlesnake (Crotalus viridis helleri) hibernates during the cold fall and winter months. During the warm spring and summer months however, rattlesnakes are active, putting pets at risk for snakebites. Although they mostly hunt at night, rattlesnakes are often found moving about during the day. Both baby rattlesnakes and adult rattlesnakes are poisonous. Snakebites most commonly occur on the face and feet because dogs and cats usually sniff or paw at snakes when they find them. The most common initial signs of a rattlesnake bite are a surprised painful reaction by the pet (e.g., a sudden onset of yelping or crying after sniffing in the bushes), followed by a progressive, often severe, swelling of the bite area.
One or more bleeding fang puncture marks may be visible. Bruising of the bite area may also be seen. Occasionally, rattlesnake bites can be difficult to distinguish from an allergic reaction to a bee or wasp sting. As the venom begins to work, the victim may develop other symptoms such as tissue death, nausea, weakness, lethargy, muscle twitching, spontaneous bleeding, abnormal heart rhythms, respiratory depression, shock, coma, and death. These additional symptoms may occur soon after the bite occurs or may not be seen for hours. Depending on the type of rattlesnake involved, mortality rates from snakebites in pets, if not treated, can be anywhere from 10 to 35%.
In as many as 20% of rattlesnake bites, no venom is injected into the victim. Unfortunately, outside of a research laboratory, there is no way to determine how much venom is released by a rattlesnake in any given case of snakebite. The degree of swelling and the severity of pain are not reliable indicators of the amount of venom injected, as these signs can be minimal, but shock and death may still occur. First aid measures such as ice packs, tourniquets, incising the wound and applying suction are not effective and may be detrimental. The best thing to do for a dog or cat bitten by a rattlesnake is to seek veterinary attention immediately.
Although there are many medical factors to address and monitor in the case of a rattlesnake bite, the most important part of treatment is the administration of antivenin. Antivenin serves to neutralize the snake venom and must be administered by intravenous infusion in a veterinary hospital setting. Early treatment is recommended to increase your pet's chances of survival and recovery. When pets bitten by rattlesnakes are treated aggressively and early, the mortality rate is less than 1%.
Avoidance of rattlesnake bites is always best if possible. Keeping your pet on a leash and not allowing him or her to run off trail during rattlesnake season is advised. Various groups offer rattlesnake avoidance training classes for dogs. Your veterinarian can refer you to a class in your area.