Mrs. Rosner was frantic when she called to report that their cocker spaniel, Monty, had just appeared at the back door with a baby rattlesnake in his mouth. She and her husband were pretty sure that it had bitten him on the muzzle, so they rushed Monty to our hospital right away. As I entered the treatment area, I could see that Monty was panting and uncomfortable. After carefully examining him for any puncture wounds that might indicate a snake bite, I noticed two tiny spots of blood on his muzzle.
To evaluate the severity of this bite, we drew a blood sample to run tests. When I looked at a drop of his blood under the microscope, I found further evidence that the snake venom was at work. The red blood cells, normally round and smooth, had formed spikes on their outer membranes. We sometimes see these damaged cells, called echinocytes, as a result of a rattlesnake bite. Also, the remaining tests showed that Monty’s blood wasn’t clotting properly.
Besides affecting the blood itself, a rattlesnake bite disrupts the integrity of the blood vessels. Combined with the change of normal blood clotting mechanisms, as we were seeing in Monty’s case, this can lead to dramatic swelling, with up to a third of the total blood circulation being lost into the tissues in a matter of hours. Sometimes, if the swelling persists despite antivenin treatment, so much blood is lost from circulation that the dog dies of shock.
We immediately started Monty on intravenous fluids to replace the lost blood, pain medication to ease his discomfort, injections of antihistamine to minimize a possible allergic reaction to the antivenin, and antibiotics to prevent an infection from the bite wounds themselves. We followed with his first vial of antivenin to counteract the poison. Since dogs can have an immediate and severe allergic response to the antivenin, we gave it very slowly and watched for signs of a reaction. Monty did fine with this injection. We attached an ECG so that we could monitor his heart, got ready to measure the swelling on his muzzle every 15 minutes, and retested his clotting abilities and red blood cell count.
After 15 minutes, we discovered that the swelling was getting worse, and it had spread farther back onto Monty’s head and around his neck. He started to have trouble breathing. We began giving him the second vial of antivenin and rechecked his blood values. I explained to Monty’s owners that the next step would be either to sedate Monty and place a breathing tube, or to perform an emergency tracheostomy, a cut into the windpipe to allow Monty to breathe better. He would also need blood transfusions.
Unfortunately, Monty had a couple of factors working against him in his encounter with the rattlesnake. First, he was bitten on the face, making it more likely that he would have breathing trouble. And his relatively small size made it more difficult for his body to overcome the effects of the venom. I explained, in light of the severity of Monty’s reaction to the bite and his failure to respond to the treatments thus far, it was looking like he might not pull through.
With Monty’s condition continuing to decline the Rosners and I discussed other options, including euthanasia. Though they were grief-stricken by the thought of the loss of Monty, they made the very difficult decision to end his suffering. I assured them that this was probably the best action to take with Monty, who had gone downhill fast with no certain outcome of improvement. So they said their final goodbyes to Monty while I placed him into his last peaceful sleep.
Avoiding or Treating Snakebites
Getting out and enjoying nature with you dog is usually a wonderful experience for both of you. But since encounters between dogs and rattlesnakes can be so serious, it pays to think about the possibility ahead of time. When out walking, hiking or camping with your dog, take precautions from early morning to late evening, as temperature, season and humidity can all affect just when rattlesnakes will be active.
Some people mistakenly believe that rattlers are active only during the hottest hours. Actually, they often rest during the heat of the day, sheltered from the sun. Like their predominantly rodent prey, these snakes are instead most active during the evening, night and morning hours.
Most snake bites to humans occur when snakes are either inadvertently stepped on or when people are trying to kill or catch them. Unfortunately, the same rattle that serves as a warning to people and is effective in preventing an unfortunate encounter, serves as a source of attraction to our curious canine friends, often leading to bites on the face or paws.
It’s a good idea to keep your pet on a leash when hiking or exploring rattlesnake habitat, so that if you hear a rattle, you can keep your pet away from the snake. If your dog is bitten by a rattlesnake, we recommend that you do not use ice or other cold applications and that you do not apply a tourniquet as these may increase the dog’s anxiety and cause him to struggle, making the effects of the snakebite worse. Instead, keep your dog as calm and quiet as possible and drive immediately to the nearest veterinarian.
Dr. Deirdre Brandes is a veterinarian at the Rancho Santa Fe Veterinary Hospital located at Helen Woodward Animal Center. She can be reached at 858-759-8797. The cases described in Veterinary Vitals are true stories, but the author has changed details about the patients to protect their privacy.