Abstract

Thirty-two sub-adult to adult rose-haired tarantulas (Grammostola rosea) were randomly divided into two groups. One group was anesthetized with 5% isoflurane in oxygen and the other with 100% carbon dioxide. The tarantulas were anesthetized in a chamber fashioned from a clear plastic jar. Isoflurane was delivered by a standard veterinary vaporizer. Carbon dioxide was supplied via a laparoscopy insufflation unit. Times to first effect, loss of righting reflexes, loss of movement with and without external stimuli, and recovery time were recorded (Table 1). Subjective comments regarding the anesthesia episodes were also recorded. Statistically significant differences were detected between the groups in all of the recorded times. Animals anesthetized with carbon dioxide had a shorter time to first effect and loss of movement as well as a reduced recovery time in comparison to those in the isoflurane group. Subjectively, the tarantulas anesthetized with carbon dioxide seemed distressed during induction and recovered in an agitated state. Tarantulas anesthetized with isoflurane had a smoother induction and recovery, but often displayed some movement in response to stimuli for extended periods of time. All tarantulas recovered completely and have remained healthy for greater than 2 years following the experiment, with the exception of two animals which died from apparently unrelated causes.

Both anesthetic agents appear to be safe and efficacious as used in this study. It should be noted that repeated carbon dioxide anesthesia causes impaired reproduction, growth and survivability in a number of invertebrate species.^1-4 The tarantulas in this study did not show any obvious ill effects following carbon dioxide or isoflurane anesthesia, but reproductive behavior and capability was not evaluated.

Table 1. Comparison of carbon dioxide and isoflurane anesthesia characteristics in rose-haired tarantulas (Grammostola rosea)

Acknowledgments

The authors would like to thank Shane Christian for managing the tarantula colony at the North Carolina State College of Veterinary Medicine.

Literature Cited

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4.  Tanaka, A. 1982. Effects of carbon dioxide anesthesia on the number of instars, larval duration and adult body size of the German cockroach, Blattella germanica. J. Insect Physiol. 28(10):813–822.