Laboratory Investigations for Snake Bite

Simple tests, which demonstrate that blood will not clot, are of great value in making the diagnosis and also determining further antivenom requirements. If facilities for sophisticated investigations (e.g., clotting times, fibrinogen levels, fibrin degradation products, red cell and platelet counts) are available they should be undertaken, as this may not only help the individual animal, but will enhance knowledge of the venom's actions. This is particularly important for the less dangerous snakes, where information is often absent.

Venom detection kits are widely used for human snake bite victims but, due to their expense, are infrequently used in veterinary practice. This test identifies the type of monovalent antivenom to be used if the animal is envenomed, but does not itself indicate whether antivenom should be given. Whereas venom may often be detected in the serum of small animals, it is far less likely to be detectable in serum taken from a very large animal such as a horse. In most cases involving horses a positive result may only be obtained from the rarely-found bite site. Urine, particularly if it is concentrated, may be a good sample for venom detection.

Generally, urinalysis is also helpful in assessing renal function and the severity of myotoxicity. Urea, creatinine and electrolytes provide important tests of renal function particularly important in cases of black and tiger snake bites. 

Similarly, plasma creatine kinase levels have been found to be highly elevated in cases of snake bite. It can be anticipated that this enzyme might be raised after bites to animals by a wide range of Australian dangerous snakes, but not after bites by death adders or eastern brown snakes.

From a practical point of view the most valuable tests are coagulation studies and plasma creatine kinase estimations.

Note that due to the latent effects of snake venom, all suspected snake bite patients must be closely observed for a minimum of 24 hours.