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Rattlesnake Bites
Tue, July 3rd, 2012

Unfortunately rattlesnake bites are common during the warm months in many regions of California. Approximately 10 to 25% of all bites are “dry” bites in which no venom is released. In the remainder, a lethal amount of venom may be transmitted. But there is no way of telling ahead of time into which category the patient falls. The severity of envenomation depends on several factors, including the location of the bite, how much and what type of venom the snake injects, how young the snake is, and whether it is early or late in the season. (Dogs are most commonly bitten on the nose as they investigate the snake.) Pets who have been bitten by a rattlesnake usually suffer from a large painful swelling. Signs of toxicity may develop as rapidly as in 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. The rapid loss of fluid into the swelling can cause shock. Infection at the site is a concern, and the massive swelling can lead to damaged tissue that may slough later. If there is a large amount of swelling in the face or neck, it may impair breathing.

The types of venom that may be transmitted include one which is damaging to the neurologic system, causing muscle weakness, tremors, paralysis, seizures and death; another type of venom has effects on the blood system including destruction of red blood cells, which causes anemia, damage to the blood clotting proteins which may lead to bleeding tendencies, and decreased platelets, which also causes a problem with bleeding; and finally the third type of venom may cause effects on the heart, including arrhythmias and death.

Treatment includes IV fluids for shock, antibiotics, antivenin, pain medications, and possibly steroids. Platelets and clotting ability are monitored, and plasma and/or blood transfusion or additional antivenin may be necessary if a clotting problem develops. The pet’s ECG is monitored for arrhythmias.

The majority of animals we treat for rattlesnake bites recover, however, even with aggressive treatment not all survive. Cats and small dogs may have a poorer prognosis due to their body size compared to the venom dose.

If your pet has been bitten, seek immediate emergency care. Restrict the pet’s activity to decease circulation of the venom (preferably carry the pet if possible). Do not apply a tourniquet or ice, and do not try to suck the venom out of the wound. Elevate the affected area if possible.

If you live in an area with rattlesnakes, you might consider taking your dog to a rattlesnake aversion class, to teach the dog how to avoid rattlesnakes. There is also a new rattlesnake vaccine available for dogs. You may wish to discuss the pros and cons of vaccination with your veterinarian.

Please note: This site is intended as a general information site only. We cannot offer advice or provide diagnosis or treatment protocols on a pet we've never seen. Our patients are seen by referral only from your primary veterinarian. If you have questions, please call us.