Northern Pacific Rattlesnakes in the Methow Valley
Vaccine, aversion training make encounters safer
By Ashley Ahearn
Dr. Michael Marrone still remembers the little terrier mix that was bitten on the tongue by a rattlesnake. The dog’s tongue turned black and started to swell, causing it to choke and begin to suffocate. Fortunately, the owner saw the bite happen and rushed the dog to Methow Valley Veterinary Hospital.
“That made all the difference, otherwise that dog would have died,” Marrone said.
Marrone was able to administer antivenom, which costs several hundred dollars, and took the dog home for the night to keep it on an IV and monitor its recovery. The dog was back to normal by midnight, Marrone said.
There are other precautions dog owners can take as the temperatures rise and rattlesnakes come out of their dens to sun themselves and look for prey.
Vaccinating against venom
One cheaper option than antivenom is a vaccine, which was developed by a veterinarian in California. The vaccine boosts the dog’s resistance to snake venom for several species of rattlers, including the Northern Pacific Rattlesnake, which is found in the Methow Valley.
“It is not a cure. The vaccine is to buy time for the animal,” said Beth Coehlo, vice president of human resources at Hygieia Biological Laboratories, which manufactures the vaccine. “We always recommend that people take their animal to the veterinarian. The vet can monitor and decide if your pet needs antivenom as well.”
More than 4 million doses of the vaccine have been sold since it was introduced in 2003, Coehlo said, adding that sales of the vaccine have risen between 5 and 15 percent per year, depending on the weather. A long hot summer is good for rattlesnakes, and vaccine sales. The company’s largest markets are in Texas and California. It has recently begun selling a vaccine for horses as well, with sales of that vaccine rising by more than 30 percent last year.
The vaccine has been effective in the Methow Valley. Dr. Terry DeWeert, owner of Valley Veterinary Clinic in Twisp, recalls that when she began administering the vaccine to her clients she saw a marked decrease in snake-bitten dogs coming to her for emergency care. She says that is not because dogs aren’t being bitten by rattlesnakes, it’s because the vaccine reduces their reaction. An owner of a vaccinated dog may not know their dog has been bitten unless they see some swelling and spot tooth marks, which can still become infected, DeWeert warned.
DeWeert recommends that her clients get their dogs vaccinated in the spring to boost immunity before rattlesnake season heats up.
Teaching aversion
An inquisitive dog will undoubtedly be drawn to the suspicious sound of a rattler. But there are ways to train your dog out of that behavior. Every year, Marrone invites an organization called Natural Solutions to conduct a dog-training workshop at his clinic in Winthrop.
The trainers bring in live snakes, which are muzzled, and use shock collars on the dogs to teach them to steer clear of the serpents. The final test of the workshop involves putting a snake on the ground between the dog and its owner. When the owner calls it, the dog will hopefully skirt around the snake on its way to its owner.
“It’s worked really well for my clients,” Marrone said. “I’ve heard about dogs avoiding snakes on the trail, numerous times.” The cost of the workshop is $75 and it will take place on June 23 in the parking lot outside the Methow Valley Veterinary Hospital in Winthrop. Pre-registration is required.
Living in snake country
There is only one kind of rattlesnake that calls the Methow Valley home. The Northern Pacific Rattlesnake is a pit viper whose venom contains hemotoxic elements, which destroy red blood cells and skin tissue and can cause bruising, swelling and internal bleeding. This may sound like a highly undesirable set of symptoms but when compared to rattlers in other parts of the country whose venom contains neurotoxic elements — which can paralyze bite victims and shut down their neurological systems — localized swelling and bruising may not seem quite so bad.
John Rohrer, a range and wildlife program manager with the U.S. Forest Service, has been studying rattlesnakes in the Methow Valley for 20 years.
“The cool thing about rattlesnakes is that they den communally,” Rohrer explained. “You’ll find hundreds in the same den. Then when the weather warms they disperse across the landscape.”
By late April, the rattlesnakes will start moving away from their den site toward their summer range, which is usually within a mile or so of the den, though some large males have been documented 3-4 miles from their den, Rohrer said. The largest rattlesnake he’s seen here measured 4 feet long.
Rattlesnake hot spots in the valley include Pipestone Canyon, Gunn Ranch and the Rendezvous area. “Mazama and the Goat Wall geologic feature provides ideal denning habitat so there are a lot of snake dens in that area as well,” Rohrer added.
Rohrer said rattlesnakes don’t want to attack unless absolutely necessary. “Most snake bites occur when people are trying to capture, kill or harass snakes,” he said.
If you encounter a snake on the trail, Rohrer said the best thing to do is to back away or go around it.
