A HUMANE ALTERNATIVE TO THE MEASUREMENT OF THE LETHAL EFFECTS (LD50) OF NON-NEUROTOXIC VENOMS USING HENS EGGS

The accurate measurement of venom lethality is the basis of clinical t reatment of snakebite and of much venom-related research. Lethality te sts are necessarily carried out in animal models and the results extra polated to man. While we may be confounded by the obvious limitations of this approach, we can improve the situation by using a non-sentient living system, such as the very early developmental stage of the chic k embryo, as an alternative to lethality testing in mammals. The conti nuing need for lethality testing of venoms and their isolated componen ts, which underpins the development and assessment of antivenoms, curr ently accounts for thousands of mice annually; this is becoming increa singly unacceptable, first because of the amount of suffering caused a nd second, because of the high cost incurred. We describe here the use of 4-6 d old chick embryos as a system for estimating venom lethality . The shell-less yolk sac membrane offers a vascular system which deve lops before intact nervous reflex arcs are functional and therefore th e embryo is incapable of experiencing pain. Venom is applied to the me mbrane on a filter paper disc and its effects on vascular and cardiac function are easily observed throughout the 6 h experiment. Eight veno ms tested on eggs and by conventional LD50 assays in mice were compare d. A highly significant correlation was obtained suggesting that this simple and inexpensive test would be a far more acceptable: alternativ e for non-neurotoxic venoms. (C) 1998 Elsevier Science Ltd. All rights reserved.