We all know that these hot summer days can bring the rattlesnakes out of their dens to get a little sun.  Apparently they aren’t worried about melanoma, but that’s another day’s topic…….  Okay, Smokey and Sassy (names have been changed to protect their identities) are not your typical rattlesnake bite victims.  These two toy breed dogs live in a small, country town outside of Billings.  They are mostly outside just to “do their business”, then they are likely to be found on their owners’ laps!  So when they presented this week with facial swelling, pain and lethargy, we thought it must be an allergic reaction to a bee sting or a spider bite, as these are quite common this time of year.  We were quite surprised when the owner found a small rattlesnake under the cupboard in the house where they keep the dog food.  Somehow this little guy got inside the house and struck the dogs when they were sniffing around for their food.

Venomous snake bites tend to occur when the snake feels threatened, as they might when a dog comes sniffing their way.  In our area, the most prevalent venomous snake is the rattlesnake (Crotalus).  Rattlesnakes are Pit Vipers, who have heat-sensing pits located between the eye and the nostil, hinged fangs and triangular-shaped heads.  Water moccasins, cottonmouths and copperheads are also pit vipers.

The venom of a pit viper is produced by a modified parotid gland (like a salivary gland in humans) and is transported to the fangs by contraction of the muscles in the head/jaw.  The fangs contain a duct that opens near the tip.  American pit vipers can choose how much venom and when venom is actually released during a bite.  Some bites are actually called “dry bites” as no venom is released.  This is the reason for the variation in how serious a bite is and how much tissue damage is done.  As veterinarians, we often don’t know until the symptoms progress, how serious the bite might have been.  In the case of  Smokey and Sassy, they both exhibited severe swelling of the face and neck region, but Smokey’s symptoms became worse over time, indicating that he likely received more venom than his sister.  Sassy’s bite may have even been a dry bite; even though no venom is injected, there is still considerable pain and swelling associated with the bite.

Pit viper venom contains several toxins intended to immobilize and digest their prey.  The typical symptoms we see with rattlesnake bites indicate that the myotoxin, anticoagulant, and cytotoxic properties are very prevalent.  The symptoms include pain, muscle and tissue damage and swelling, and bleeding tendencies due to the destruction of  blood clotting cells and mechanisms.  Other toxic properties include neurotoxins, designed to paralyze the victim, nephrotoxins which cause serious kidney damage and cardiotoxins, which affect the heart muscle and cause serious hypotension (low blood pressure).  As you can imagine, all of these toxins acting together are very potent and can easily lead to death or severe disability of the victim. 

Smokey actually had more severe blood clotting symptoms and developed bruising on his chest and abdomen as his blood clotting cells decreased.  Along with this, his red blood cell percentage decreased, due to the blood pooling in his subcutaneous tissues (bruising).  Both dogs developed significant edema/swelling in their head and neck, which gradually spread to ventrally (to gravity-dependent areas – chest and legs).  These dogs were treated with intravenous fluids, pain relievers, anti-inflammatory medication and antibiotics.  Anti venom is not frequently given to dogs, due to its enormous cost, and most dogs will survive rattlesnake bites with aggressive medical care given as early after the bite as is possible.  We also treated the edema and swelling with our Therapeutic Laser, which helps remove inflammatory products from the affected tissues.   Read more about Laser therapy here:  https://www.billingsanimalfamilyhospital.com/services/laser.html

At Billings Animal Family Hospital, we offer the Rattlesnake vaccine.  The vaccine is intended to lessen the severity of symptoms should the patient be bitten.  It doesn’t mean that veterinary care isn’t necessary!!  We have actually had two patients “test” the vaccine for us and it did seem that their symptoms were less severe than non-vaccinated dogs.  Of course we don’t know about the severity of the bite either (size of the snake, amount of venom, etc).  The vaccine is initially given and boosted one month later.  Following the initial series, it is given annually.  This is one vaccine that has a fairly high rate of vaccine reactions, up to 20%,  although none have been any more serious than swelling or a small sterile abscess lump at the vaccine site.  For dogs at risk of getting bitten, I think the benefit far outweighs the risk of these mild vaccine reactions.  Dogs at risk might be hunting dogs, dogs that hike along the Rims or Phipps park, country dogs or even the toy breeds who rarely go outside!! 

Smokey and Sassy went home 3 days after they initially presented.  They were both stable, doing well and their family was grateful to have them home!!  They will return for follow-up blood counts and laser treatments until the majority of the swelling and bruising have subsided.  I’m not sure how the rest of the family is doing knowing there was a rattlesnake inside the house!  Yikes!