Venom is a toxic fluid created in specialized oral glands related to salivary glands, and the toxic component is composed of an array of complex proteins. Every snake’s venom contains more than one toxin, and in combination the toxins have a more potent effect than the sum of their individual effects. Most of the toxic effects are due to the enzymes in the venom and there have been about twenty-five enzymes discovered so far.
Venoms are of two types: neurotoxic (affecting the nervous system) or hemotoxic (affecting the blood and vessels). The venom of many snakes contain both neurotoxic and hemotoxic components.
Venomous snakebites cause severe pain, cell death, numbness, diminished function and, occasionally, loss of a limb. Snake venoms inflict local effects such as inflammation, damage to blood vessel lining, clotting defects and localized tissue destruction. Some venom can also cause neurotoxicity and interfere with nerve transmission resulting in paralysis.
Antivenin is a serum that is commercially produced to neutralize the effects of the injected venom. At special laboratories healthy horses are injected with increasing amounts of selected snake venom (non-fatal, of course), gradually challenging the horse to make more antibodies. To obtain these antibodies, a small amount of blood is later removed from the horse and the protein antibodies are separated out and purified.
A specific antibody is produced for each type of snake. According the Dr. Schaer the newer antivenins are ovine derived and very expensive at $1500 per 2 vials. Severe envenomations might require as many as 10 vials.
Should dog owners carry antivenin kits with them routinely while outside with their dogs? Probably not, says Dr. Schaer.
"An antivenin kit probably wouldn't be that practical because of expense, routes of administration and other important reasons."
Most antivenin products are targeted for a particular species of snake and may have no effect on the snake that bites your dog. Antivenin may not have a long shelf life and due to expense, most animal hospitals so not keep a supply on hand.
Above all, be vigilant when walking with your dog in areas inhabited by poisonous snakes. It’s not a bad idea to memorize your veterinarian’s emergency phone number, too!
Image: Greg Schecter / via Flickr