Snakebites create concern for livestock owners, pose health risks
“Rattlesnakes are a threat to animal health, and some years are worse than others for snakebites,” Wyoming State Veterinarian Jim Logan says. “From what I have heard from ranchers and people out on the land, this appears to be a bad year.”
In Wyoming, the prairie rattlesnake and its more venomous cousin, the midget faded rattlesnake, are two concerns for recreationalists and producers in the state.
“The prairie rattlesnake is found east of the Continental Divide and at lower elevations,” says Zach Walker, Wyoming Game and Fish Department herpetologist. “The midget faded rattlesnake is found primarily in the Flaming Gorge area and down through Colorado.”
“When a horse or a cow gets bitten, it will usually be on the nose or the head. Livestock are curious animals, and when they try to examine the snake, they can get bit,” Logan says.
“Snake venom components vary tremendously by snake species,” says Cynthia Gaskill, clinical veterinary toxicologist at the University of Kentucky, in her article on thehorse.com. “However, most venoms contain substances that cause digestion and breakdown of tissues and blood vessels, impair blood clotting and damage the heart.”
The age of the snake also influences the toxicity of bites.
“With the prairie rattlesnake, there is a twofold consideration with age. The little ones don’t know how to meter their venom, meaning they can expel some, all or no venom, in a bite. It is usually all or nothing with the little ones,” Walker explains.
“As rattlesnakes get older, their prey sometimes changes, and the toxicity of the venom can change depending on what they are feeding on,” he says. “This is the same case in the midget faded rattlesnake, but they have a more potent venom than the prairie rattlesnake.”
“Both species are fairly shy and docile and are not likely to bite unless something steps on them or they feel immediately threatened,” Walker adds.
Clinical signs of snakebites can vary, but generally include pain and swelling at the bite site, one or more puncture wounds and sloughing of tissues near the bite site.
“Severe bites from more dangerous snake species or larger doses of venom can cause marked pain and swelling, coagulopathy – which is a defect in blood clotting, hemorrhage, cardiac arrhythmias, shock, collapse and, in some cases, death,” explains Gaskill.
Various factors influence the severity of a bite, including size and age of the animal, concurrent medical conditions, drugs the animal is receiving and the location of the bite.
“It is important to understand that, while one snakebite incident in one animal might be mild and not require treatment, a different snakebite involving a different snake, a different animal or different circumstance might be much more severe and even fatal,” Gaskill adds.
“By a time a snakebite is noticed in livestock, it is usually too late to aspirate the poison because it will have dissipated from the site of the bite,” says Logan. “It is best to take the animal to receive veterinary attention immediately.”
“Many anecdotal or folk remedies can cause more harm than good,” Gaskill says. “Additionally, suction devices designed specifically for venom removal have not been shown to be beneficial in pig models.”
Gaskill says the best first-aid is keeping the animal calm and arranging for immediate care.
“Even after horses have recovered from a bite’s more immediate effects, subsequent complications, such as chronic heart failure, kidney damage and hemolytic anemia – which is a disease in which the body’s immune system attacks and kills its own red blood cells, can sometimes occur,” she continues.
“Cardiac failure can occur weeks to months after the bite incident and appears to be more common in horses than other species,” Gaskill adds. “Horses that have recovered from snakebites should be evaluated every few months for cardiac health, and owners should be watchful for signs that might suggest cardiac problems.”
A vaccine is now available for use in horses to help prevent complications of snakebites, but its efficacy is not yet well documented.
“I think vaccines help a little bit, but they won’t negate the effects of the poison entirely,” says Logan. “The exposure to the venom from the vaccine will only help to marginally desensitize the animal.”