A quantitative study of venom secretion by Vipera palaestinae.

Abstract

Summary Observations on the secretion of venom by 150 captive Vipera palaestinae indicate that snakes separately caged and properly cared for may be milked regularly for 3 years or longer, and large quantities of venom can thus be obtained. With artificial heating, the milking can be continued throughout the year. No influence of ecdysis, pregnancy, or food consumption on the yield of venom was observed. Taking into account the amounts and concentration of the venom obtained as well as the physical well being of the snakes, a period of rest of one month between milkings is suggested. Temperature was found to be one of the factors governing the venom yield. A rise in temperature increased both the amount and the concentration of venom. The freshly secreted venom is rather dilute initially, and is subsequently concentrated by the reabsorption of water. The amount of venom injected in a single bite was estimated by allowing the vipers to strike dead mice. The amount injected was found to range from nil to 190 mg of fresh venom; in most bites less than 50 mg amounts (mean, 32 ± 3.1 mg) were injected. The mean proportionate amount injected was approximately 11% of the venom available in the glands; in most strikes less than 15% of the available venom was injected. Results obtained in the laboratory when considered in relation to the severity of viper bites in human beings suggest that the minimal lethal dose of Vipera palaestinae venom for man is approximately 75 mg.