Especially during the spring and summer months, dogs may encounter a rattlesnake. Bites are commonly on the head or muzzle. Bites to the torso tend to have lower survival rates.
An envenomated rattlesnake bite is a definite canine emergency requiring appropriate veterinary care as soon as possible, to increase the chances of survival.
First aid in the field is not an option.The bottom line is to minimize the amount of time it takes to get the dog to a vet that may administer antivenin and minimize the irreversible effects that can occur.
Diagnosing the bite
If the handler witnesses the bite, it is important to identify the snake and/or kill it to bring to the vet for positive identification. Do not bring in a live snake for obvious reasons. If the snake is killed do not damage the head since positive identification is based in part on morphological characteristics of the head.
Identification is important: some rattlesnake bites may be especially dangerous to dogs. The mortality rate for Northern Pacific rattlesnakes is about 10% compared to the Mojave rattlesnake whose bite has a mortality rate around 35%.
Snake bites that are not witnessed are problematic, since signs and symptoms can be similar for bee stings and other bites. A handler that hears his canine partner yelp out in pain but does not see the snake may not know what happened. Visual inspection of the dog may not show the snake bite puncture wounds depending on the density of the dog’s fur and location of the bite. The bite may only produce a single puncture wound. Determination of a snake bite may be difficult.
Signs and symptoms
Fortunately, less than half of canine snake bites produce signs and symptoms.
A dry bite is still very painful to the dog and requires vet care and possible treatment to prevent infection. A handler cannot know whether the bite is dry or envenomated and should assume the worse.
An envenomated rattlesnake bite results in series of rapidly developing symptoms that are life threatening to the canine. The Merck Veterinary Manual provides the symptoms and potential course of treatment(s) to increase the chances for survival. According to the Merck Manual an untreated envenomated bite typically results in death within the first two hours. If the dog survives the first 24 hours it is generally assumed it will continue to recover. The subsequent ten days are critical to prevent anaerobic infections from the puncture wounds.
Transporting the dog
Experienced vet care including life support cannot be duplicated in the field.
Transport of the immobilized dog is important to prevent the spread of venom through tissues surrounding the bite. Immediate and painful swelling may occur in the area around the bite. Make sure to loosen the dog’s collar and any other harnesses, etc. since swelling is immediate. A muzzle may be needed since the bite is very painful. The puncture wounds may not be visible through the fur but can ooze blood. Destruction of the tissue near the bite is rapid and spreads quickly. It is recommended to get the dog to a vet as soon as possible but preferably within 4 hours after the bite. Therefore a handler should always carry the name and number for the nearest vet with antivenin and driving directions for transport to the animal hospital.
The use of corticosteroids in the field may be helpful and reduce allergic reaction to the antivenin but cannot be used alone. Antivenin is not stable or appropriate for use by the professional handler.
Treatment is time critical to prevent the spread of venom and the profound cardiopulmonary and/or neurological effects.
Prevention
Handler awareness of the dog’s surroundings and activities is the best prevention. If the dog is working in rattlesnake habitat, then a basic knowledge of the types of snakes that may be encountered is desirable. The name, number and location of the nearest vet within antivenin is essential. Prevention of rattlesnake bites should be considered before entering the field. Review what the dog will be doing prior to deployment. Ask Ranger’s or local authorities about snake activity in the area. Canine handler’s should wear the appropriate clothing and boots. Safety of the dog and also the handler is first.