Rattlesnake Bites

• If bitten, remain calm and get to a veterinary hospital. Do not delay seeking treatment, due to time of night, holidays or weekends.
• Call ahead to the hospital so that the emergency room and physician can prepare for arrival of the patient.
• Remove anything from the body that may cause restriction (collars, choke chains, harnesses) before the swelling begins.
• Although some disagreement exists among veterinarians, tourniquets, incision and suction, or treatment with ice usually are not recommended. All of these methods tend to increase tissue damage and may delay treatment.
• Nose and head bites are dangerous because swelling may cut off nasal or tracheal air passages.

Rattlesnake bites are common during the warm months in many regions of California. Bites from venomous snakes can be horribly painful and result in permanent damage. However most animals will survive if taken immediately to a veterinarian for treatment. Cats and small dogs may have a poorer prognosis due to their body size compared to the venom dose. The severity of the envenomation depends on several factors, including the location of the bite, how much venom is injected, what type of venom the snake injects, the age of the snake, and whether it is early or late in the season. Bites that occur from baby rattlesnakes are particularly dangerous due to their lack of control of the venom released and they are more easily provoked.

When an animal is bitten, rapid swelling takes place within the first few minutes as the venom starts to destroy tissue at the bite location and then spreads throughout the animals’ body. Signs of toxicity may develop as rapidly as 30 minutes, especially if the venom is injected directly into a blood vessel or the eye. Onset of symptoms may be delayed as long as 24 to 72 hours. Infection at the site is a concern, and the tissue in the affected area may be damaged. If there is a large amount of swelling in the face or neck, it may impair breathing.

Treatment for these bites may include antivenin injections, intravenous fluids, treatment for shock and pain, and medication for infection

• While walking dogs, keep them on a sturdy leash, maintain vigilance, and stay on open paths or trails where snakes can more easily be seen. Humans and loose dogs are in danger of being bitten if a dog disturbs a snake.
• Avoid nighttime walks in desert areas, as rattlesnakes are nocturnal during most of the year.
• If the rattles of a rattlesnake are heard, keep the dog close by and move away from the snake as soon as the snake’s location is determined.
• Should a dog seem to be unusually interested in something hidden in the brush, quickly back away until the object can be determined.
• Don’t allow dogs to explore holes in the ground or dig under logs, flat rocks or other debris where snakes may be hidden. Keep yards clean and free of potential hiding places to help discourage the presence of snakes.
• Whatever you do, DO NOT attempt to handle the snake!
• Rattlesnake Avoidance Training classes give dogs the necessary training to help prevent a potentially deadly and expensive experience. They train your dog to avoid contact with rattlesnakes. For more information on rattlesnake avoidance training and to make a reservation, go to www.patrickcallaghan.com

Rattlesnakes have two toxins of concern. The most immediate concern is due to the hemotoxin, which causes the inability to clot blood and a drop in platelet count. The second concern is due to the necrotoxin, which causes surrounding tissues to die and slough. Also of concern is managing wound infection.

Snake venom is highly complicated. At least 26 separate enzymes have been identified but some 10 enzymes appear common to all snake venoms (though in different concentrations). All snake bites are not equal. The quality of venom depends not only on the type of snake but on the season, the geographical region, the age of the snake, and how recently it has released venom previously.

It is a serum which is produced to counteract the effects of the snake injected venom. It is produced using healthy horses which are injected with increasing amounts of selected non-fatal snake venom. This gradually causes the horse to make antibodies, which are then extracted via a small amount of blood. The antibodies are then separated out and purified.

The only venomous snakes in California are the rattlesnakes and there are eight species: Pictures provided by California Reptiles and Amphibians at (www.californiaherps.com):

Southern Pacific	Great Basin
Northern Pacific

The following five pictures thanks to Biology of the Rattlesnake Symposium at Loma Linda University at: (www.roblee.com/rattlesnakes)

The Western Diamondback (Crotalus atrox)

The Red Diamondback (Crotalus ruber)

The Sidewinder (Crotalus cerastes)

The Speckled Rattlesnake (Crotalus mitchellii)

The Mojave Rattlesnake (Crotalus scutalatus), sometimes called ("The Mojave Green Rattlesnake")

The physical appearance of each snake species is variable and it is difficult to tell what species of snake one is looking at. Some general principles in distinguishing poisonous snakes are:

• Broad, triangular head with a noticeable "neck" behind the head.
• Vertical pupils (non-poisonous snakes have round pupils) though hopefully one would not be close enough to evaluate this.
• The Crotalines are also called "pit vipers" because they have heat-sensing "pits" on t heir faces between the eye and nostril. The pits help them locate prey.

Rattlesnakes can be found in rural areas as well as suburban areas where there is sufficient natural habitat. In Northern California snakes will hibernate during cold months and are active March through September. In Southern California they are active all year round.

Dogs encounter snakes during play or work in the snake’s natural habitat. Most bites to dogs occur on the face or extremities. The rattlesnake bite is generally "hemotoxic" which means that it exerts its toxin by disrupting the integrity of the blood vessels. The swelling is often dramatic with up to 1/3 of the total blood circulation being lost into the tissues in a matter of hours. The toxin further disrupts normal blood clotting mechanisms leading to uncontrolled bleeding. This kind of blood loss induces shock and finally death. Facial bites are often more lethal as the swelling may occlude the throat or impair ability to breathe.

An exception would be the Mojave rattlesnake whose venom is "neurotoxic." The bite of this snake causes rapid paralysis. This includes paralysis of the respiratory muscles and suffocation.

The faster the bite is recognized, the more effective the treatment is. Do not try to cut the bite wound open or suck out the poison. Seek veterinary care immediately for proper treatment. Treatment may include IV fluids, antivenin, antihistamines, blood transfusions, antibiotics, and/or pain relievers.

Recently, Red Rock Biologics has released a vaccination against the venom of the Western Diamondback (Crotalus atrox). This vaccine also protects against the venom of six out of seven of the other California rattlesnakes (the Mojave Rattlesnake has such significantly different venom that it is not covered). It is not effective against other species of rattlesnakes and has not been proven to prevent the effects of rattlesnake envenomation. This vaccine may reduce the overall effects of snakebites, reduce the need for antivenom, and decrease treatment costs. Protective antibodies made by your dog in response to the vaccine begin neutralizing venom right away. Therefore, vaccinated dogs are reported to experience less pain, recover faster, and have reduced risk of permanent injury from a rattlesnake bite. Dogs that go hiking, camping or hunting frequently and dogs that live in rattlesnake areas are good candidates for this product.

The initial vaccination is given in 2 doses 4 weeks apart. Annual boosters are best given approximately one month before snake season starts in the spring. Dogs who live where snake season is year round or where they hike year round should have boosters every 6 months (twice a year). If a vaccine is skipped, the initial vaccination protocol should be re-started. Vaccination is safe during pregnancy and lactation, and for puppies 4 months of age and older. Vaccination reactions occur in 0.27% of cases (27 per 10,000 doses given) and are largely limited to swelling at the vaccine site occurring 7 to 10 days after vaccination.

We do offer the Red Rock Biologics rattlesnake vaccine at Camino Animal Clinic. However, it is important to remember that the best treatment is getting your pet to a veterinarian as soon as possible after rattlesnake envenomation. A snake bite should always be treated as an emergency even in a vaccinated dog. If your dog is bitten by a rattlesnake, seek veterinary attention immediately.

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