Tuesday, June 28, 2011

Heather Smith Thomas: Notes from Sky Range Ranch — Snakebite!, Part Two: Treating the Bite

To read Part One of this story, click here.
To browse all Notes From Sky Range Ranch, click here.

There are generally two things to worry about in a snakebitten animal: swelling and infection. Swelling can shut off air passages, and the bite may also create a nasty infection from the dying tissue. Necrotic tissue around the bite can send infection throughout the body, creating fever and illness (blood poisoning). This is why a bite in soft tissues such as around the nose or in a muscle can produce more adverse affects than a bite on the lower leg of a horse or cow. The bone is not affected much, but soft tissue can become infected.
Antivenin, if it’s available and if given soon enough, can reduce tissue reaction. Cleaning and disinfecting the bite can also help. According to our local veterinarian, a portion of the antivenin shot can also be injected locally, in the area of the bite.
Most veterinarians recommend putting the animal on antibiotics until the danger of infection is past. Our cow Jana already had a serious infection by the time I found her, and it was too late for antivenin, but we kept her on antibiotics for 2 weeks, until her fever subsided and she was eating and drinking again.
Our cow Jana had a serious infection.
Swelling can be dealt with in several ways. Ice packs are beneficial if the bite is in an area where you can apply an ice pack and keep it on. Dimethyl sulfoxide (DMSO) is also good for reducing swelling and inflammation. It can be applied locally (rubbed over the area that's swelling up) and also given internally by intravenous injection (one mL per 100 pounds), where it is quickly absorbed by body tissues and reduces swelling. If you are not adept at giving an IV injection, you can give it orally, mixed with a little warm water and squirted into the back of the mouth with a syringe. If the animal is having trouble breathing, DMSO put into the mouth works very well to reduce swelling and keep air passages open.
On our way home from riding range about 20 years ago, our dog was bitten on the face, and the only thing that saved her was that we were nearly home when it happened. She was having trouble breathing, so we loaded her into the car and rushed her to the vet clinic 12 miles away. Our vet gave her antivenin and applied DMSO onto the swelling—which quickly resolved the airway restriction. Swelling will also respond to treatment with furosemide (Lasix), which is a diuretic, drawing fluid out of body tissues and causing the animal to urinate more. Effects of this drug are temporary but fast acting and can help keep down the sudden swelling from snakebite.
One year our dog was bitten on the face.
Another good drug for reducing swelling and inflammation is dexamethasone, but it should not be given if the animal is heavily pregnant. Steroids given during the last trimester of gestation can cause abortion.
In severe and acute cases of swelling on the head, if a horse or cow is having trouble breathing and in danger of suffocation, a tracheostomy can be done, making a horizontal incision through the skin and into the windpipe for the animal to breathe through. The slit should be a few inches below the jawbone, carefully cutting through the windpipe with a sharp, clean knife between the firm rings of cartilage. It's like cutting between the ridges of a vacuum cleaner hose. The animal can breathe through this slit. Keep the slit open until the vet arrives; he or she can put a tracheal tube into the hole to keep it open. After the swelling obstructing the upper air passages has gone down, the tube can be taken out and the hole stitched shut.
In severe cases of swelling on the head,
the animal may have trouble breathing.
This calf has been treated several times
and is no longer in danger of suffocating
but still has a lot of swelling and infection.
A less invasive method to keep the animal from suffocating, if you discover the problem soon enough, is to force a section of small-diameter plastic tubing (such as the nasogastric tubes we use for administering fluid to sick calves) into each nostril—far enough to get past the area that is swelling. The tube will keep the airway from closing, and the animal can continue to breathe.
One of the calves we treated for snakebite
Snakebites often become infected, and the infection is potentially more dangerous than the bite itself. When I was a child, our favorite ranch cat, Thomas, nearly died from this type of infection. He liked to kill rattlesnakes to eat: he’d tease them until they struck at him, then grab them by the neck, just behind the head. As he grew older, however, his reflexes and actions were probably not as swift. One summer he disappeared for a week, and when he finally showed up again, he was thin and weak, very ill, with a feverish shoulder—and a bare patch where the hair had fallen out, revealing the fang marks of a snake. We were amazed that he’d survived.

Our ranch cat, Thomas, several years after
he survived his first snakebite
The next year he suffered another bite, but it didn’t make him nearly as sick, and the following summer he was bitten on the front leg—and except for the obvious fang marks, you’d never know he’d been bitten. It seemed as though he was building up a tolerance or immunity to the effects of the rattlesnake bites. He was lucky to have survived the first bite, because even though he was a large cat, an animal this small is more vulnerable to the effects of the toxins in snake venom.
In the years since then, we’ve watched several of our cats playing with snakes—teasing and killing them—and we realized that cats are natural predators for snakes. They are usually quick enough that they can dodge a poisonous bite.
One of our young cats playing with a snake
There usually isn't enough poison to kill a large animal, but any animal is at risk for serious secondary bacterial infection that may result, due to contamination from bacteria that enter with the bite. The dying tissue makes an ideal place for bacteria to multiply and send toxins into the bloodstream. This infection, if not treated promptly, may cause death of the animal. Our vet recommends giving broad-spectrum antibiotics until possible infection is controlled. Tetanus antitoxin is a good idea, too (especially for a horse), if the animal's tetanus shots are not current. If the bite is several days old before it's discovered, there may be a lot of infected swelling that should be lanced and flushed out with antiseptic solution.
If the animal is ill or in shock, fluids should be given intravenously or by stomach tube. If the bite is on the head and subsequent pain and swelling make it hard to eat or drink, supportive treatment should include fluids and nutrients via stomach tube until the animal can eat again. In a large animal such as a cow, pelleted feeds soaked in water and run through a blender can be made into a thin mush and given by stomach tube in a large volume of water. We use a long, flexible tube inserted into the nostril, to the back of the throat (where the animal swallows it), down the esophagus, and into the stomach.
Our son Michael, feeding a cow pelleted grain soaked into
a mush and administered with lots of fluid via stomach tube
Good nursing care can keep the animal going until it's able to eat and drink again. We treated our cow Jana for over 2 months—the first 2 weeks to combat infection and swelling on her face, feeding her with a stomach tube for several days while she was unable to eat or drink. We spent 7 more weeks flushing and draining abscesses that kept forming from the infection in necrotic tissue in the area of the bite. Some of the dead tissue sloughed away.
Our son and his wife feeding a cow via stomach tube
Snakebite can be suspected any time you find an animal with sudden pain and swelling. If the hair coat is not too thick at the site of the bite, you may see fang marks in the swollen skin. If you suspect snakebite, immediate medical attention should be given, especially if the bite is on the head. Prompt treatment can make a lot of difference, turning a potentially serious problem into a minor one.
Heather Smith Thomas raises horses and cattle on her family ranch in Salmon, Idaho. She writes for numerous horse magazines and is the author of several books on horses and cattle farming, including Storey’s Guide to Raising Horses, Storey's Guide to Training Horses, Stable Smarts, The Horse Conformation Handbook, Your Calf, Getting Started with Beef and Dairy Cattle, Storey's Guide to Raising Beef Cattle, Essential Guide to Calving, and The Cattle Health Handbook.

No comments: