As most of our suburbs are within easy reach of forest and bushland, snakebite is a relatively common occurrence in dogs and cats.
The management of rattlesnake bites in animals presents some problems which do not occur in human medicine. Firstly, it is often not realized that a pet has been bitten unless the incident has been observed.
It is not unusual for a dog or cat to return home without any signs of a struggle, only to collapse some hours later. Even if the animal is seen to be bitten, it is not easy to identify the snake unless it is killed in the struggle.
The site of the bite in an animal is not always apparent, due to the thick hair covering. Most bites occur around the nose and head and, as these areas are well supplied with blood, absorption of the injected toxin occurs quite rapidly.
Dogs and cats are much smaller than humans and therefore the amount of toxin absorbed per kilo of body weight is higher than usually occurs in a human.
Multiple bites are also more common than in humans because whereas most people are bitten on an extremity and accidentally, often an animal is attempting to kill the snake.
Symptoms that develop after a snakebite do not indicate the type of snake involved. The predominant symptoms common to all snakebites is paralysis.
After being bitten the dog is usually highly excited. It soon lies down and pants rapidly. If it tries to rise it might collapse after only walking a few steps. Vomiting can occur and, as the venom produces its effect higher up the spinal cord, death occurs from respiratory paralysis.
Cats seem to be more resistant to snake venom than dogs. Symptoms can take some hours to develop. The cat is usually found lying on its side, unable to move its limbs or raise its head. The pupils of the eye are widely dilated and its breathing is usually labored.
Snakebite is treated by an intravenous injection of the appropriate antivenom. Where the type of snake is not known, different types of antivenom are usually given.
In human medicine, where the snake has not been identified, the patient is given polyvalent snake antivenom. This product is prohibitively expensive and is not usually used in veterinary medicine.
Attempts to scarify the wound only waste valuable time and might even help to further disseminate the toxin. As most bites occur around the head in animals, procedures such as compression, bandaging and splinting the area are not applicable in veterinary first aid. The animal should be kept as quiet as possible until veterinary attention is obtained.