Maintaining rear-fanged snakes for venom production: an evaluation of mortality and survival rates for Philodryas olfersii and P. patagoniensis in captivity

This study evaluates the mortality and average survival rates of captive female Philodryas olfersii and Philodryas patagoniensis snakes maintained for venom production. Also, two factors likely to reduce captive survival were studied - body condition at admission and seasonality. Mortality peaks occurred during the second month in captivity. More than half the individuals were dead at the end of the third month. This suggests that the first three months in captivity are the most critical in terms of survival and adaptation. Females collected and admitted during spring and summer lived less time than those collected in autumn and winter. As gravidity and egg-laying occur during spring and summer, we suggest that the lower survival rates in these seasons may be due to high costs and stress involved in these reproductive events. Unexpectedly, body mass and body condition were poor predictors of survival in captivity. Our results have important implications in maintaining snakes for venom production. We propose some prophylactic measures to minimize the deleterious impacts of captivity during the adaptation period.(AU)

Age-related biological activity of south american rattlesnake (Crotalus durissus terrificus) venom

An in vitro and in vivo comparative study was performed on the effects of Crotalus durissus terrificus venoms from a mother and its 15 newborns. The venoms were tested for protein content, lethality, proteolytic, myotoxic, hemorrhagic, and phospholipase A2 activity. The minimum coagulant dose in plasma and human fibrinogen, protrhombin, and Factor II activations were analyzed. The venoms were also analyzed by polyacrylamide gel electrophoresis (PAGE). This showed that despite similar total protein content, the biological effects of the venoms were different. Venom from young snakes exhibited higher enzymatic and coagulant activities and higher myotoxicity compared to the mother's. In addition, the PLA2 content paralleled myotoxicity. However, no difference could be detected in their toxicity (LD50 0.08 mg/Kg). High incidence of blood coagulation disorders and elevated circulating myoglobin may characterize systemic envenoming by young C. d. terrificus.