Thermal shock in a colony of South African clawed frogs (Xenopus laevis)

Captive frogs die after rapid rise in water temperature

source S.L.Green et al:
Veterinary Record vol 152, no 11, March 15 2003
starts p336, 2 pages long

The sudden death of South African clawed frogs at Stanford University, US, led to an investigation into possible causes. There were 200 adult, female frogs housed in a 300 litre laboratory tank, and 22 of these frogs were found dead, followed by a further 17 found dying or dead eight days later. No pathogens were found, histological examinations showed no abnormalities, and the water quality did not appear to be at fault. Four moribund frogs were euthanased and found to have haemotological profiles of cold-adapted amphibians. The 39 affected frogs had all come from a holding tank kept at 16 degrees C to boost oogenesis. The profiles fit with data on cold adaptation in amphibians from other studies. This species of frog prefers a water temperature of 21 deg C to 24 deg C, but can tolerate variations in temperature up to between 31 deg C and 39 deg C, so long as the change in temperature occurs over some hours. The frogs had been transferred from water at 16 deg C to 23 deg C, and had suffered from acute thermal shock. Other species of frogs have been affected by sudden, small temperature rises between 2 deg C and 5 deg C.

Laboratory practice was changed, allowing the frogs to acclimatise overnight in a 3 litre bucket, with a 23 deg C - 25 deg C ambient temperature. After this change in practice, there were no more deaths from thermal shock.