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EQUINE HEALTH
If you find an animal that’s been snake-bitten, try to
give emergency treatment without moving that animal very much--since increased activity and blood circulation will spread the toxins farther.
Two things to worry about in a snake-bitten animal are swelling and infection. Swelling on the face can shut off the airways and cause the horses to suffocate, and dying tissue around a bite can send infection through the body, causing fever and blood poisoning (septicemia).
TREATMENT
There are two things to worry about in a snake- bitten animal, according to Robert Cope, DVM from Salmon, Idaho: swelling and infection. Swelling on the face can shut off the airways and dying tissue around a bite can send infection through the body, causing fever and blood poisoning (septicemia). A bite in soft tissues can become infected. Cleaning and disinfecting the bite can help. He advises use
of antibiotics until danger of infection is past. Your veterinarian can prescribe the appropriate antibiotic.
A tetanus vaccination is also a good idea (es- pecially for a horse or pet) if the animal’s tetanus shots are not current. If the bite is several days old before discovered, there may be a large infected swelling that should be lanced and flushed.
Some kind of anti-inflammatory medica- tion should be given to reduce swelling and pain. DMSO (dimethyl sulfoxide) gel or liquid can be rubbed over the area that is swelling. If the animal was bitten on the face and is having trouble breathing, liquid DMSO can also be given orally--mixing it with a little warm water and squirting it into the back of the mouth with a syringe, where it is rapidly absorbed and can help keep air passages open by halting the tissue swelling. Another drug often used for reducing swelling and inflammation is dexamethasone.
In severe cases of swelling on the head where the animal is in danger of suffocation, immedi- ate treatment is crucial. “If you can catch it early enough, just starting to swell, the veterinarian can put an endotracheal tube with a cuff into the na- sal passage to keep it open while we do something to reduce the swelling,” says Fuselier.
“If the veterinarian can’t get there quickly, the animal owner could stick a 6 to 8-inch piece of hose (or a plastic syringe barrel) into one of the nostrils,” he says. For a calf or small horse, smaller tubing would work. Lubricating the end of the tube makes it easier to insert.
If the swelling is too far along and the airways are already squeezed shut and the animal
can’t breathe, an emergency tracheostomy is necessary to maintain an active air passage. It’s best if this can be done by a veterinarian, but if there is no way he/she can get there on time, the owner could try to do it.
“You 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. Then use your fingers to open that slit a bit wider side to side so you can make a stab incision between the rings. If that’s not enough of a hole, you can cut a small circle, removing
a portion of the cartilage ring to make a bigger hole. Often a pocketknife stab is enough be- tween the rings to get it open for air flow. If you have to, you can slip a small piece of hose or tube into that hole to keep it open. This could buy the animal time until the veterinarian arrives and can take it from there,” says Fuselier. After the swelling is resolved and the windpipe is no longer restricted, the incision can be sutured.
“A bite on the leg is usually not as serious, depending on where it is,” Fuselier says. “The higher on the leg (such as near the armpit or groin), the worse it might be. The toxins could get into the bloodstream quicker. We worry about that with some bites, because there’s more risk for anaphylactic shock. The toxins may also rupture red blood cells, and this could lead to organ failure, starting with the kidneys.
“But usually what you see first is a localized swelling from the bite. It may then progress along the leg as a generalized swelling or celluli- tis in the soft tissues. The best way to treat that would be to surgically debride that area to cut out the dead tissue and get down to the healthy tissue, and clean the wound,” he says.
Snakebites often become infected, and this can be more dangerous than the bite itself, says Cope. There usually isn’t enough toxin to kill a large animal, but bacteria often enter with the bite--and the dying tissue makes an ideal place for bacteria to multiply.
“Every animal responds differently to the tox- ins,” says Fuselier. “The toxin is a foreign protein, so some individuals will have an allergic type of reac- tion. In some animals the toxins spread very rapidly within the body, and in others they won’t. It’s not very common to have two cases that are identical.”
Swelling around the face/muzzle area may be so extensive that the animal can’t eat or drink. Sup- portive care may be necessary, such as feeding with a tube (via the nostril or down the throat, depend- ing on where the swelling is least obstructive). If the animal can’t eat or drink, you need to provide fluid and nutrition a different way to buy some time until the swelling goes down. Your veterinarian can help give advice on supportive care, as well as treat- ment, since each case will be a little different.
SNAKEBITE VACCINE
There is an equine vaccine for snakebite. For many years there has been a snakebite vaccine for dogs, and more recently a vaccine for horses--to protect the horse throughout the summer from effects of rattlesnake venom. Dose is important; you want to achieve a high enough antibody level to protect the animal, based on its size. The smaller the animal, the more at risk it will be.
The recommendation when vaccinating horses is to start the first year with 3 doses a few weeks apart, and then a booster every 6 months if you live in areas like certain parts of Texas and southern California where rattlesnakes are out year-round and never go dormant.
In northern areas where snakes are out for only a few months in summer, you give a booster once a year--about a month before snakes start coming out. This gives horses enough time to ramp up immunity and be fully protected by the time they come into contact with rattlesnakes.
This vaccine was created specifically against venom from Western Diamondback rattle- snakes and is most effective against this snake’s venom, but since venom from many other
SPEEDHORSE August 2020 65
Barney Nelson