Few medical emergencies are as terrifying as snakebites. They happen fast and they’re dangerous. Will your dog survive? Knowing what to do and acting immediately can save your pet’s life.
Thousands of dogs are bitten in the U.S. each year by venomous snakes. Ninety-nine percent of the snakes that bite them are pit vipers, whose Crotalidae family includes Copperheads, Cottonmouths (Water Moccasins), and more than a dozen species of rattlesnake. The remaining one percent are Coral snakes, native to the American Southeast and Mexican border.
Rattlesnakes account for most U.S. snakebite-related deaths in humans and domestic animals. According to the Animal Medical Center of Southern California, dogs are 20 times more likely to be bitten by venomous snakes than humans are, and 25 times more likely to die as a result. Snake bites are life-threatening, painful, expensive to treat, and can cause permanent damage even when the animals survive.
Thanks to his owners’ quick action nine years ago, Gizmo, a Yorkshire Terrier, recently celebrated his 15th birthday. One August night, as Micheline Campbell of Belt, Montana, and her husband were getting ready for bed, they let Gizmo outside one last time for the night. “A few minutes later, we heard him yelp and went to see what was wrong. A baby rattlesnake coiled up on the patio had just bitten Gizmo on his leg.”
Campbell’s husband, Mark, put a garbage can lid over the snake and brought Gizmo into the house. “Within two minutes he started whining and within five minutes he was yelping like he was being beaten,” she says. “We called our veterinarian, Dale Schott, DVM, who lives just a mile away. He told us to bring Gizmo right over. As we were transporting him, Gizmo lost consciousness. This was about 10 minutes after being bitten.”
Fortunately, Dr. Schott keeps a supply of antivenom (also known as antivenin) on hand. This antidote is administered intravenously or, in some cases, injected into muscle close to the bite location.
Dr. Schott mixed the antivenom with distilled water to hydrate it. “During the mixing, which seemed to take forever, Gizmo lay motionless on the table,” Campbell says. “Both Mark and I were sure he had died. Dr. Schott shaved a spot on Gizmo’s front leg to find a vein and then injected the antivenom. Within a few seconds, Gizmo started showing signs of life, and within about 15 minutes, it was as though he had never been bitten. The vet gave him a shot of Benadryl and kept him overnight. When we picked him up in the morning, he was fine.” Gizmo’s only lasting symptom is that he licks his leg every day.
Gizmo was lucky to have received veterinary attention and antivenom so quickly. Pit vipers give birth to live babies whose fangs and venom help defend them against predators. The snake that bit Gizmo was very young (rattlesnakes are generally born between August and October). “We learned that baby rattlesnakes are more potent than adults because when they bite, they release all of their venom,” says Campbell. “An adult snake releases venom according to the size of its prey.” In addition, the venom of young snakes may contain more neurotoxic elements.
It’s an emergency!
The bite of most pit vipers is called “hemotoxic,” meaning that its venom disrupts the integrity of blood vessels. As a result, dramatic swelling, blood loss, and uncontrolled bleeding can quickly lead to shock and death. Up to one-third of a dog’s blood supply can be lost to tissues within hours, causing a severe drop in blood pressure.
Most dogs are bitten on the face or leg. Facial bites can be serious if swelling closes the throat and impairs the dog’s ability to breathe, but in general, bites to the face or legs are considered less dangerous than bites to the torso, especially the chest or abdomen, where they can directly affect the body’s organs.
As the Merck Veterinary Manual explains, “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).”
According to Animal Pharm News, published by the University of California Davis Veterinary Medical Teaching Hospital, it’s important to:
- Remain calm.
- Wash the bite with clean water and soap.
- Keep the animal quiet.
- Immobilize the bitten area and keep it lower than the heart.
- Seek veterinary help immediately, even if you are not certain that it is a rattlesnake bite.
- Call an emergency veterinary clinic ahead so they can prepare.
- Remove restrictive collars, choke chains, etc., before swelling begins.
- Unless the bite is on the head or face, consider applying a muzzle to protect anyone who handles the dog, as extreme pain can cause any dog to bite.
The terms antivenom, antivenin, and antivenene all refer to a biological product used in the treatment of venomous bites or stings. It is created by milking venom from a specific snake, spider, or insect, then diluting the venom and injecting it into horses, sheep, rabbits, or goats. The injected animal’s immune response produces antibodies against the venom’s active molecule, and these antibodies are extracted from the animal’s blood and freeze-dried. Antivenoms sold internationally conform to the World Health Organization’s standards of pharmacopoeia.
The term antivenin, which is derived from the French venin, meaning poison, has been in use since 1895. In 1981, the World Health Organization adopted the English terms venom and antivenom, replacing the terms venin and antivenin, or venen and antivenene. Antivenoms have been created for dozens of poisonous snakes, spiders, and scorpions around the world.
Rattlesnake antivenom has been a miracle cure for many American dogs, but for the treatment to be successful, it has to be the right product and it has to be administered in time. Antivenom is considered most effective if administered within four hours and less so after eight hours, but it is still recommended as a treatment for severe symptoms within 24 hours. However, much depends on the bite’s location, the dog’s size and overall health, and the venom’s toxicity. Rattlesnakes tend to be most toxic when very young, agitated, angry, or targeting prey.
The antivenom also has to be available, and it often isn’t. Many veterinary clinics, even in areas inhabited by rattlesnakes, don’t carry it. This is because antivenom is expensive, has to be stored at a stable room temperature, and has a limited shelf life. Cost is an important factor, for not everyone can afford the treatment.
Several antivenom products are available to veterinarians, including:
– ACP from Boeringer Ingelheim Vetmedica is currently the only USDA-approved antivenom for use in veterinary medicine. While considered effective against the hemotoxic effects of all North American Rattlesnakes, Copperheads, and Cottonmouths, it is not effective against the Mojave Rattlesnake’s neuro-toxins. The cost to veterinary clinics averages $300 to $500 per vial. ACP’s manufacturer recommends between one and five vials per patient, depending on the dog’s size, condition, and symptoms, and in some cases higher doses are needed. Even when only one or two vials of ACP are sufficient to slow or halt the progression of clinical signs, the cost to clients can be prohibitive.
– CroFab® is an antivenom from sheep exposed to venom of the Eastern Diamondback, Western Diamondback, Mojave Rattlesnake, and Cottonmouth. This antivenom is more rapidly reconstituted and about five times more potent at neutralizing pit-viper venoms in animal models than ACP. Its small molecules are rapidly cleared from circulation, and it is well tolerated by patients allergic to horse-derived products. CroFab is expensive. Depending on the distributor, a veterinary clinic’s cost may be $1,000 per vial or more. One prospective veterinary clinical trial reported that most dogs required 1.25 vials on average.
– Antivipmyn®, an equine serum manufactured by Bioclon Institute in Mexico, is considered highly effective against North American pit vipers, but repeated doses may be needed. This antivenom tends to be significantly less expensive than others. It requires a USDA importers’ license and permission from the State veterinarian prior to purchase.
– Another Mexican product, Crotalid Antivenom®, is derived from horses exposed to the Tropical Rattlesnake and Fer-de-lance. A retrospective analysis of 180 dogs treated with this antivenom in Arizona found that one vial was sufficient to improve clinical signs in most patients, and it was shown to resolve both neurologic and myotoxic effects of rattlesnake bites. An experimental safety trial in healthy dogs demonstrated no acute or delayed reactions when up to six vials were administered over one hour. This antivenom is available for veterinary use with a USDA import permit. The average cost to veterinarians per vial is $300.
– Coralmyn®, manufactured in Mexico with venom from the Black Banded Coral snake, has been shown to neutralize Eastern Coral snake and Texas Coral snake venom. This antivenom is available for veterinary use with a USDA import permit. An antivenom for the Coral snake went out of production in 2006; the snake is so rare that its antivenom wasn’t profitable.
Allergic reactions to the serum components of antivenoms are less common in dogs than humans, but they can occur. In 2005, the Journal of Veterinary Emergency and Critical Care reported the first known case of antivenom-associated serum sickness in a dog. The patient, a Boxer, had been bitten by an Eastern Diamondback Rattlesnake and was in shock and suffering blood loss.
Three days after treatment with ACP, the dog developed an allergic reaction with a fever, limb edema, and eye swelling, symptoms that continued through the sixth day of hospitalization. As physicians do for human patients, some veterinarians test for serum allergies with a skin test before administering antivenoms, but their results are not always accurate.
Controversial Vaccine
Researchers at Red Rock Biologics developed a rattlesnake vaccine, Crotalus Atrox Toxoid, that can be given to horses and dogs in advance of a trip to rattlesnake country or before rattlesnakes become active (generally in spring and summer), in an effort to reduce the adverse effects of rattlesnake bites and allow extra time for conventional treatment.
The venom used in its production came from Western Diamondback Rattlesnakes, so it is considered most effective for that species, but it is assumed to protect against related venoms, such as the Western Rattlesnake (including the Prairie, Great Basin, Northern, and Southern Pacific varieties), Sidewinder, Timber Rattlesnake, Massasauga, and Copperhead. Partial protection may be obtained against Eastern Diamondback Rattlesnake venom. The vaccine does not protect against venom from Cottonmouths, Mojave Rattlesnakes, or Coral snakes. In 2012, Red Rock Biologics began developing a vaccine for the Eastern Diamondback and similar species.
According to the manufacturer, “As part of its licensing process, this vaccine was shown in dogs to generate protective antibodies against rattlesnake venom. Protective antibodies function by neutralizing rattlesnake venom. Dogs with protective antibodies are reported to experience less pain and have a reduced risk of permanent injury from rattlesnake bite. Veterinarians typically report that vaccinated dogs bitten by rattlesnakes experience less swelling, less tissue damage and a faster recovery from snakebite than unvaccinated dogs.
“Several factors may influence antibody effectiveness against venomous snakebite. Snake-related factors include the snake species, age of the snake, and amount of venom injected. Dog-related factors include location of the bite, how well the dog responded to the vaccine, and the length of time since the last dose of vaccine was administered.”
It takes four to six weeks for the vaccine to produce maximum protection, and that protection continues for approximately six months. The manufacturer recommends an initial vaccine followed by a booster dose one month later and an annual booster after that. In some cases, anticipated rattlesnake exposure or the dog’s size require two or even three booster shots per year. Search and rescue dogs, hunting dogs, small dogs, unusually large dogs, or dogs living in high-density rattlesnake areas where snakes are active year round may benefit from booster shots every four months.
The rattlesnake vaccine is considered safe for use in pregnant and lactating dogs, puppies as young as four months, and healthy older dogs. Side effects reported by veterinarians have typically been few and mild. Less than one percent of vaccinations result in a mild swelling at the injection site.
How effective is the vaccine? That’s a good question. The manufacturer recommends treating every snake bite as a medical emergency, for even vaccinated dogs may need antivenom and other conventional care. No objective studies testing the vaccine have been published. Not all species of snakes are well covered by the vaccine, individual patient responses vary, the amount of venom in a bite might overwhelm a vaccinated dog’s immune response despite high titers, the dog might receive multiple bites with the same result, or the bite might be near vital organs or a vein. In addition, the vaccine does not protect against tissue necrosis or infection.
Because of the vaccine’s cost, questionable efficacy, and the fact that vaccinated and unvaccinated dogs receive the same veterinary care when bitten, many veterinary hospitals do not recommend it for their canine patients. At the same time, for dogs at high risk in areas where immediate treatment is impossible, the vaccine might delay the venom’s effect so that the owner can reach a veterinarian in time to save the dog’s life or decrease the venom’s effects.
Conventional Care
Because most deaths and adverse reactions to rattlesnake bites result from blood loss causing circulatory collapse, intravenous fluids (sodium chloride or colloid fluids) are given to maintain blood pressure. Oxyglobin, which is chemically stabilized bovine hemoglobin used to treat anemia in dogs and which has fewer risks of causing clotting abnormalities, can be given instead. In rare cases, if uncontrolled bleeding is life-threatening, blood transfusions may be needed.
In addition to fluid therapy, anti-histamines and steroids can help prevent further swelling and anaphylactic (allergic) reactions. Because of increased mortality rates reported in human patients, steroids are controversial, but they may help patients with recurrent bites or symptoms of serum sickness.
Antibiotics are used to prevent secondary bacterial infections of the bite site. Because venom can spread rapidly in an agitated patient, pain killers such as fentayl or diazepam may be given to relieve severe pain and agitation. Anti-inflammatories are not used because they may worsen bleeding problems.
An estimated 20 to 25 percent of rattlesnake bites to dogs are “dry,” meaning they don’t contain venom; another 30 percent produce mild local symptoms of pain and swelling; 40 percent are severe; and approximately 5 percent of rattlesnake bites are fatal to dogs.
Follow-up care includes at least eight hours of observation, for mild bites can become severe and dry bites can become infected. The wound should be rechecked within two or three days, at which time follow-up bloodwork can be performed.
Provide plenty of fluids, and return to the veterinary clinic if the dog’s urine decreases in quantity or becomes dark and cola-colored, if swelling worsens, or if the dog develops dark, tarry stools, new bruising, or signs of wound infection, such as redness, heat, pus drainage, or extreme tenderness.
Do not administer anti-inflammatory drugs such as carprofen, meloxicam, or aspirin for at least two weeks after a snakebite. Limit the dog’s physical activity and avoid surgery or dental work during that time. Return if the dog develops a fever, rash, itching, joint pain, or swollen lymph nodes within a month.
Snake Bites and Homeopathy
Before he became interested in homeo-pathy, Douglas Falkner, MD, MHom, was a Level I Trauma Center emergency physician. “Emergency physicians confront and successfully manage life-threatening problems on a daily basis,” he says, “but most homeopaths, at least in the U.S., rarely have an opportunity to test the efficacy of homeopathy when accident, injury, or illness brings one toward the brink of death.”
Dr. Faulker was camping in Oregon’s remote high desert, when a rattlesnake bit Bob, a fellow camper’s Border Collie-Lab mix, on the right side of his forehead. Bob lay on his side, with the right side of his face dramatically swollen, his right eye completely shut, his swollen jowl sagging, and heavy drool hanging from the side of his mouth. The lightest touch made him yelp in pain. His owner, Don, decided that because the nearest veterinary clinic was far away and it was late in the day, transporting the dog was not an option.
Dr. Falkner checked his collection of homeopathic remedies and selected two that he thought would help: Lachesis (potentized venom from the South American Bushmaster, or Suruku, the world’s longest pit viper) and Cedron (a potentized plant known as “Rattlesnake Bean”), both in a 30C potency.
He diluted each of the remedies in a cup of water, labeling them to avoid confusion later, and instructed Don to alternate doses, giving a spoonful of one or the other every five minutes for four doses of each altogether.
Half an hour later, Bob was moving more, wagging his tail, and looking up. His swollen right eye was beginning to open. Then Dr. Falkner suggested alternating doses every 15 minutes, and when he returned after an hour, Bob stood to greet him. “His face was still swollen and he was drooling,” he says, “but Bob was becoming more animated. He was acting more dog-like and less ill. His eye was now half visible. When I patted him, he didn’t yelp like before. The pain seemed significantly diminished.”
Don continued alternating doses every half hour, then during the night gave Bob one or two doses of each. The following morning when Dr. Falkner went to check on him, Bob ran to greet him with a wagging tail and both eyes wide open, showing no signs of illness. “There was still some boggy edema under his jowls,” he says, “but it seemed to have no negative impact. He was clearly well and thriving!”
Bob had already eaten breakfast, consumed large amounts of water, and eliminated on his normal schedule. Don weaned Bob off the remedies by extending the time between doses for another day. “When the patient responds quickly and well,” says Dr. Falkner, “you can extend the treatment by a couple of doses and then stop. Use common sense and gauge the speed of improvement. A dog that improves quickly can stop quickly, while one that recovers slowly should disengage slowly.”
Although Bob had a speedy recovery, Dr. Falkner advises that it is always prudent to seek conventional medical care in emergencies where bites from venomous animals can cause serious injury or death. However, such options are not always available, as in a wilderness setting like this one.
After his report of Bob’s rattlesnake bite appeared in a 2013 holistic health magazine, Dr. Falkner heard from two dog owners who reported that the same remedies, administered as described, worked perfectly for their dogs’ venomous snake bites. “While there is typically no universal remedy in homeopathy, as individualization is the rule,” he says, “there are circumstances where a specific remedy will work most of the time. Our tradition states that symptoms are the guideposts to treatment, and most snake bites will start off causing similar symptoms. The size or breed of the dog makes no difference at all. Lachesis and Cedron are the two remedies I would carry with me and use first off in the event of such an emergency.”
There are other homeopathic remedies available for snake bites, including Crotalus horridus, the Timber rattler, and Crotalus cascavela, a Brazilian rattlesnake. In reply to our questions, Dr. Falkner agreed that a homeopathic Crotalus remedy could work well for rattlesnake bites, assuming the symptoms of the remedy agree with the symptoms of the patient.
Ounce of Prevention
The first rule of common-sense bite prevention is to understand snake behavior and use that knowledge to avoid encounters. You and your dog are most likely to meet a rattlesnake while hiking, climbing, camping, or just walking on a trail. If you live in rattlesnake country, it can happen in your own backyard!
Rattlesnakes tend to be most active during summer months, but spring and fall are dangerous throughout most of the U.S., and in mild climates (Southern California, for example, or the Southwest, or wherever temperatures stay above freezing) they can be active at any time. Their favorite temperatures are between 70° and 90°F (21° to 32°C).
Because reptiles are unable to control their body temperatures, snakes depend on their environment for comfort and mobility. In cold weather they seek warmth and in hot weather they seek shade and cooler ground. On sunny mornings you might find rattlesnakes warming themselves on asphalt or driveways, but encounters are more likely to occur around rocks, shrubs, brush, woodpiles, or wherever snakes can hide.
While walking where rattlesnakes are known to be, keep your dog on a short leash and stay on well-defined trails, avoiding tall grass, brushy areas, fallen logs, and abandoned buildings. Rocks, holes, ledges, and brush are favorite hiding places for rattlesnakes. Don’t let your dog explore holes or dig under rocks, and never let your dog examine a dead snake, as it can still be venomous.
If you notice a snake, back away quickly and quietly. Keep in mind that a rattlesnake’s striking distance is half to two-thirds of its body length, and it strikes faster than the human eye can follow. Always keep a considerable distance between a snake and your dog. Be careful around water because rattlesnakes swim, and anything that looks like a long stick might be a snake.
Rattlesnakes feed on rodents and other small animals, and whatever you can do to remove their food supply will make your property less attractive to them. Below-ground fencing, frequent mowing, rodent-control measures, and wire mesh that blocks small holes or cracks under doorways and in garages and other buildings will encourage snakes to depart. Store firewood away from your house, plug holes in the ground, and limit birdseed waste, which can attract rodents.
Experts advise against using caustic lye or products such as gels, powders, and ropes that are advertised to deter snakes as these are ineffective and potentially harmful to pets and children.
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