|
Clinical signs
-
Salvation, hyperexcitability, mydriasis, asphyxia, gasping, recumbency, convulsions and death in 2-4 hours. Regurgitation of ruminal contents, paralysis of the tongue, oesophagus and larynx are noticed in ruminants.
-
Diagnosis: Diagnosis is based on sudden death, fang marks, local swelling and oozing of blood from the site of bite. Typical pit viper bites are characterized by severe local tissue damage that spreads from the bite site. The tissue becomes markedly discolored within a few minutes and dark, bloody fluid may ooze from the fang wounds if not prevented by swelling. Frequently, the epidermis sloughs when the overlying hair is clipped or merely parted. Hair may hide the typical fang marks. Sometimes, only one fang mark or multiple punctures are present. In elapine snakebites, pain and swelling are minimal; systemic neurologic signs predominate.
Treatment
-
Snake bite is an urgent emergency. In some cases, it is lethal, in many it can cause prolonged and disfiguring injury. Although the animal should receive veterinary care as soon as possible, this should be done while keeping the animal as quiet as possible.
-
Even if the snake is killed for identification purposes, caution must be exercised in handling it after death. Envenomation is possible even after a poisonous snake has been decapitated.
-
Objectives of therapy are to neutralize the venom, prevent shock, and prevent secondary infections; and sometimes to prevent the further spread of toxins, and remove the venom. The use of alcohol to clean the wound is contraindicated because of its vasodilatory effect, which would promote uptake and spread of venom.
-
Includes administration of the specific anti-venom is the species of snake is known, administration of polyvalent anti-venom if the species of snake is not known and symptomatic.
-
Broad-spectrum antibiotics should be given to prevent wound infection and other secondary infections. Several potential pathogens, including Pseudomonas aeruginosa, Clostridium spp., Corynebacterium spp. and staphylococci have been isolated from rattlesnakes’ mouths. Antibiotics should be continued until all superficial lesions have healed.
-
Respiratory assistance (ventilator) may be needed for 48 - 72 hours for animals with coral snake poisoning. The maintenance of a patent airway is critical. Large diameter tubing or opened syringe cases are commonly placed in the nostrils of horses bitten on the face to keep the airways open. Emergency tracheostomy may be required.
-
Fluid therapy: Generally indicated in small animals. Hypotension is a common presenting sign. Diuresis to facilitate excretion and renal damage has been reported to be useful in man.
-
Corticosteroids: Use is controversial. Useful in treating shock but increases in mortality have been reported with their use. They can also alter results of laboratory tests that are otherwise useful in monitoring an animal's progress. Generally used for prevention of shock and hypotension. May not affect local swelling.
-
Transfusions: Commonly indicated in dogs, if necessary, to treat anemia and hemorrhage.
-
Tetanus antitoxin should always be given to the affected horse.
-
Antihistamines have been reported to be contraindicated, but diphenhydramine hydrochloride is frequently given along with antivenin to treat snakebite in humans. Tranquilization in horses may be required.
Therapies generally contraindicated
-
Tourniquet - The use of tourniquets is controversial and usually they are avoided. When used they are most effective in first 30 minutes. Tourniquets increase local tissue damage due to hypoxia. The general location of snake bites (e.g., face) may prevent use. Recommended only for animals in which the tissues below the tourniquet will be sacrificed to save the animal's life.
-
Incision and suction - Also controversial. Requires restraint of animal to be effective. Minimal benefit with regards to the local removal of venom. Not recommended unless pocket of venom will clearly be removable.
-
Cryotherapy - Commonly associated with increased tissue damage. Not recommended.
-
Surgical debridement - Use has not been substantiated. May result in serious scarring and loss of function. May not prevent systemic signs. Not recommended early in course of treatment for envenomation.
|
Participants