July 7, 2016
A cool, wet spring has transformed into the heat of summer. While that means easier living for both you and your cattle, it’s still prudent to keep your eyes peeled for the hidden and well-camouflaged danger lurking behind a pair of snake eyes. Indeed, you roll the dice when poisonous snakes are around.
The rattlesnake is the most common poisonous snake in the U.S. It belongs to a family of snakes called pit vipers that have heat-sensing organs on their heads, which help them locate prey. Other pit vipers include copperheads and cottonmouth, also called water moccasin. The rattlesnake usually gives a warning when an animal or person approaches, unless the rattles are wet; but copperheads and sometimes rattlesnakes may just try to hide — and then you or a cow or your horse might step on them and get bitten.
The danger/potency of a bite depends on amount of venom injected and the type of toxin — which can vary, depending on the species or variety of snake. It also makes a difference where the bite is located. A bite on the leg is usually not as dangerous as a bite on the face. Swelling from a bite on the nose, for instance, may cause death from suffocation if it shuts off the air passages and the animal cannot breathe.
Matt Miesner, associate professor in the Kansas State University College of Veterinary Medicine, says large animals like cattle are rarely killed by snakebite because the amount of venom per unit of body is small. “They are less apt to suffer heart failure, kidney failure or all the other things that might be more dangerous for a person or smaller animal,” he says.
Often, the toxins from a bite result in damaged tissue and a lot of necrotic (dead) tissue and infection. Sometimes the infection may go systemic (septicemia, or blood poisoning).
“I’ve seen two calves with black, necrotic, swollen areas on the abdomen, where I suspect they were bitten when they lay down on or near a snake. These calves were very sick, and the necrotic tissue was sloughing off. Both of these calves died; the infection was too severe for them to recover. With their smaller body mass, they were more seriously affected than an adult cow might be,” he says.
Rob Callan, head of livestock veterinary services at the Veterinary Teaching Hospital at Colorado State University, says the good thing is that most cattle don’t seem to get too “nosy” with rattlesnakes.
“Most bites are on the lower legs, unless it’s a curious individual that approaches the snake to smell it. A bite on the leg shows up as a swollen leg. The biggest problem would be infection in those tissues,” he says.
The immediate problem with face or nose bites is suffocation, since snakebite can cause rapid, severe swelling. Immediate treatment and monitoring are key, as is keeping the animals confined so they don’t have to walk. If they can’t breathe well, you don’t want them exerting.
“With a bite on the nose, we often must find an alternate breathing route, and sometimes this means a tracheotomy to allow the animal to breathe while the swelling goes down,” Callan explains.
Jacques Fuselier, a veterinarian with the Whittington Veterinary Clinic, Abbeville, La., says that if you can catch a nose bite early enough, when tissues are just starting to swell, a veterinarian can put an endotracheal tube with a cuff into the nasal passage to keep it open, while giving treatment to reduce the swelling.
“If the veterinarian can’t get there quickly, you could use a piece of hose,” he says. For a calf, use smaller tubing. This can be left in until the swelling goes down.
“A piece of hose can be pushed up each nostril, all the way through the nasal passages, to maintain an open airway before they swell shut,” Callan says. The tube or hose should be secured with tape or a string on the outside to keep it from sliding in or out, or being inhaled into the trachea, or swallowed.
If the swelling is too advanced and airways are already squeezed shut and the animal can’t breathe, an emergency tracheotomy is necessary. It’s best if this can be done by a veterinarian, but if there is no way to have the veterinarian get there in time, you may have to do it to save the animal.
“Be as clean as possible, and make a vertical incision through the skin, along the windpipe, right in the middle of the throat—so you can get down to the rings of the trachea,” says Fuselier. “Then use your fingers to open that slit a bit wider side to side, so you can make a stab incision between the rings [a bit like slicing between the ribs of a vacuum cleaner hose]. If that’s not enough of a hole to let air go in and out, make a cut in a small circle, remove a portion of the cartilage ring to make a bigger hole.”
Often a pocketknife stab is enough between the rings to get it open for air flow. “If necessary, slip a small piece of hose or tube into that hole to keep it open. This buys the animal time until the veterinarian arrives and can take it from there,” says Fuselier.
After the bite
“If you see the animal bitten, or suspect it was bitten, treat with an antibiotic,” says Callan. “There are bacteria in the snake’s mouth, and bacteria that proliferate in damaged, dying tissue.”
Most common antibiotics will work to prevent and combat these infections; you can use penicillin, oxytetracycline, florfenicol, ampicillin or any other broad-spectrum antibiotic. Some animals develop a fever and/or septicemia from the infection; antibiotics can help prevent these problems.
Immediate treatment with anti-inflammatory drugs to reduce inflammation, pain and swelling can make a big difference, but it’s sometimes hard to treat cattle early because you might not see them as soon as you might notice a snake-bitten pet.
“In humans, treatment within the first couple of hours is generally accomplished, but we rarely get that opportunity with cattle,” says Miesner. “There are antivenom products that work, but those need to be infused within the first few hours. They are expensive, and they don’t cover every type of snakebite,” he says. These products are not very practical for adult cattle because it would take multiple vials for an animal this large.
Cold therapy, such as cool water from a garden hose, dexamethasone, DMSO or similar products can often help. “There are regulations regarding DMSO, but used as a topical it’s still OK,” Miesner says. “Use caution with DMSO topically on devitalized tissues, however, as this may result in absorption of contaminants and worsening of systemic disease.”
He suggests you check with your veterinarian. “We generally prefer to use steroids to help prevent or reduce swelling and inflammation. It is important to control swelling and pain, because a snakebite is horribly painful,” Miesner says.
“We don’t recommend the old treatment of slicing across a bite area and sucking out the venom. It generally doesn’t work. But after the area becomes necrotic, we may have to open it up and debride it to get rid of dead tissue that serves as a source of more infection,” says Miesner.
If the head is so swollen that the animal has trouble eating and drinking, you might have to provide fluid and nutrients via stomach tube. “Another thing we can do with cattle that can’t eat is create a port through the cow’s side into the rumen, and put feed directly into the rumen, but usually the swelling can be reduced quickly enough that we don’t have to do something this involved,” he says.
But it might not be snakebite
Glennon Mays, a veterinarian at Texas A&M University, says that a suspected snakebite could turn out to be something else. Swelling on a lower leg, for instance, is more often due to foot rot or another infection than to snakebite.
“Animal owners over the years have asked me to look at lumps on jaws, faces, necks and other body parts, swollen legs and feet, believing their animal has suffered snakebite. Snakebite wounds have a fairly typical appearance, and often some bleeding. Signs vary, depending on the length of time transpired since the bite occurred, the environmental temperature, the amount of venom and other factors that might affect the appearance of the affected area,” he says.
“Often, a swelling the owner is worried about turns out to be an abscess or seroma [collection of fluid] or reaction of body tissue, rather than snakebite. This is why it’s important to have a proper diagnosis and involve your veterinarian,” Mays says.
Heather Smith Thomas is a rancher and freelance writer based in Salmon, Idaho.
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