Snake Bites and Horses

My husband and I trail ride for pleasure these days. We ride in a low-lying area along Lake Jackson in Manassas, Virginia as well as at Manassas Battlefield. The poisonous snake that we are most likely to encounter is the copperhead. There are, however, a number of other type of poisonous snakes found throughout the United States such as cottonmouths, rattlesnakes of various kinds: timber rattlesnakes, pygmy rattlesnakes and Diamondback rattlesnakes, and water moccasins. These type of snakes are called pit vipers. They are also known as Crotalinai or pit adders. It is interesting that these snakes have a special heat sensing hole or pit organ located on either side of the head between the nostril and the eye. It helps them find the warmth of mammals and other living things. Their heads are in the shape of a triangle which helps to identify them.

Copperhead

Our two horses, Rusty Man and A Patchy Star, are both from Kentucky. There are a number of poisonous snakes found there including copperheads, cottonmouths, water moccasins, timber rattlesnakes, pygmy rattlesnakes and the Eastern Diamondback rattlesnakes. The Diamondback rattlesnakes are the most poisonous of this group. The copperheads are the least poisonous although they do deliver a nasty bite called a dry bite and if the snake injects venom the reaction is much worse.

We have been trail riding and actually have encountered copperheads on the trail. They can also be encountered in the pasture or even the barn areas. If a horse is bitten by one of these poisonous snakes the venom causes the breakdown of the horse's tissues and blood vessels, affects the clotting blood and damages the heart. Several factors influence the severity of the snake bite including the amount of venom injected, the size and weight of the horse, the location of the bite, the age of the horse, the horse's overall health and drugs that the horse might be taking.

• Swelling at bite site
• Sluffing off of facial tissue if bitten in the face or on the lips or nostrils
• Lameness
• Usually two puncture wounds where fangs went in
• Pain
• Problems with blood clotting
• Hemorrhaging
• Arrhythmia
• Shock
• Collapse
• Respiratory Distress
• laminitis
• Diarrhea
• Pneumonia
• Paralysis of muscles that govern swallowing
• Wound complications
• Death

If your horse is bitten by a snake call your vet immediately. If you are on the trail do not ride your horse but rather walk your horse back to the trailer or home. Some vets will actually meet you at your riding site. You do not want to have the venom move rapidly through the horse's bloodstream through the body. If a stall is available put your horse in it to keep him/her quite. If a stall is not available put your horse in a calm environment. Your vet will assess the severity of the bite and the treatment will be given accordingly. Treatment has a wide range depending on the severity of the bite and the location of the bite. Veterinary treatment will vary depending on the severity of the bite, but might include "treatment for shock, fluid therapy, pain medications, wound treatment and antibiotics, tetanus prophylaxis, and antivenin. Antivenin can be especially helpful in cases of severe envenomation and can decrease the amount of tissue damage and hasten recovery times. Antivenin is dosed according to the estimated amount of venom injected, not the size of the patient, so even one vial of antivenin can help counteract venom toxins in a horse. Cardiac arrhythmias occur in many horses and might require treatment. Horses with severe nasal passage swelling might need treatment to maintain a patent airway and nutritional support if swelling impairs the horse's ability to eat and drink." Horses can have residual problems from snake bites including heart trouble or even heart failure, kidney damage, hemolytic anemia, general weakness and strained breathing. They need to be watched closely during and after recovery.

Note: "...Viperine snakes are located throughout the Americas, however, and they have hinged fangs that strike, penetrate and withdraw. The motion is not unlike that of an intramuscular injection. The venom of these snakes is mainly hemotoxic consisting of potent enzymes and peptides. A vasculitis quickly occurs and massive edema, local bleeding and eventual tissue necrosis can occur. These problems can lead to tissue damage and skin necrosis even if the victim recovers and some local neurotoxins can lead to persistent lameness in some cases...." Snakebite!

A vaccine is now available for use in horses to help prevent complications of snakebite. However, the efficacy is not yet known. Ask your vet about it for more information.

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