Last week, during my occasional hikes around my home, I came across a 4-foot rattlesnake and then shortly after that I encountered a 3-foot bull snake. I am not sure if the mild winter or the above average precipitation have anything to do with an increase in snakes this year, but it is important for people to be able to identify the difference between poisonous and non-poisonous snakes.
As for livestock owners, they can usually identify rattlesnake bites on their livestock without much difficulty, even if they did not witness the strike. A rattle-snake bite results in almost immediate swelling, and a darkening of tissue to a dark blue-black color. Bites will also reveal two fang marks in addition to other teeth marks (all snakes have teeth; only pit vipers have fangs too).
Of the 21 species of rattlesnakes found in the western U.S., the Prairie Rattlesnake is the most numerous and the Western Diamondback is the largest. The rare Mojave Rattlesnake inhabits southern parts of California, Nevada, Arizona, New Mexico and southwestern Texas.
The toxins in rattlesnake venom immobilize and kill prey (generally small rodents) and break down their body tissues to start the digestive process. The main toxins are mycotoxins (the primary toxins in Western Diamondback venom), which create rapid swelling, pain and bleeding at the bite site and hemotoxins (the main toxin found in Prairie Rattler venom) that damage the blood vessels.
The toxins create inflammation, tissue destruction and blood vessel leakage – allowing the venom to spread.
Horses are extremely sensitive to snake venom. They are followed, in order, by sheep, cows, goats, dogs, pigs, and cats. Humans are moderately sensitive and fall somewhere between dogs and pigs. Horses and cattle, though very sensitive, seldom die as a result of snakebites. A lethal dose of venom is based on body weight and fortunately most horses and cows are simply too large for snakes to kill. A large animal will generally survive the bite unless infection develops or the bite is on the muzzle. If the animal is bitten on the muzzle or throat area swelling from the bite may restrict air passages and can result in suffocation.
Rattlesnakes often bite livestock on the nose or head as the animals attempt to investigate them. Sheep, in particular, may crowd together in shaded areas near water during midday. As a consequence, they also frequently are bitten on the legs or lower body when pushed close to snakes.
The progression of events after a rattlesnake bite can be divided into 3 phases: the first 2 hours, the ensuing 24 hours, and a variable period (usually approximately 10 days) afterward. The first 2 hours is the acute stage in which untreated, severely envenomized (bitten) animals usually die. If death does not occur during this period, and the untreated animal is not in shock or depressed, the prognosis usually is favorable. If the animal is active and alert after 24 hours, death is unlikely. The third phase is a convalescent period in which infection may be of concern.
Treatment
The two primary concerns for snake bitten livestock are: 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). It is important to clean and disinfect the bite. Antibiotics should be administered until danger of infection is past.
DMSO (dimethyl sulfoxide) can also be administered to reduce the pain, swelling and inflammation. DMSO gel or liquid can be rubbed over the area that’s 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 the air passages open by halting the tissue swelling. Use caution with DMSO topically on devitalized tissues, as this may result in absorption of contaminants and worsening of systemic disease
In severe cases of swelling on the head, where the animal is in danger of suffocation, immediate treatment is crucial. If the veterinarian can’t get there quickly, the stockman could stick a 6-inch to 8-inch piece of hose (or plastic syringe barrel) into one of the nostrils, 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 (the animal can’t breathe), an emergency tracheostomy is necessary to maintain an active air passage. This is best done by a veterinarian.
Usually, a bite on the leg is not as serious, depending on where it is. The higher on the leg (such as near the armpit or groin), the worse it might be. Normally, a bite to the legs will be indicated by localized swelling from the bite. It may then progress along the leg as a generalized swelling or in the soft tissues. In most bites to the leg area, there usually is not 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.
Fatal snakebites are more common in dogs than in other domestic animals. Because of the relatively small size of some dogs in proportion to the amount of venom injected, the bite of even a small snake may be fatal. In dogs and cats, mortality is generally higher in bites to the thorax or abdomen than bites to the head or extremities.’ If you suspect that a snake has bitten your canine family member, do not delay in rushing him to the veterinary emergency clinic.
There is a canine rattlesnake vaccine. This vaccine is for use in healthy dogs to help decrease the severity of rattlesnake bites. The vaccine works by stimulating the dog’s immune system to produce antibodies against rattlesnake toxin.
Snakebites are true emergency. Rapid examination and appropriate treatment are paramount. Owners should not spend time on first aid other than to keep the animal quiet and limit its activity. The following commonly touted measures are ineffective and can be potentially harmful: use of ice, cold packs, or sprays; incision and suction; tourniquets; electric shock; hot packs; and delay in presentation for medical treatment (waiting until problems develop).
