Pathologic changes associated with use of tribromoethanol (avertin) in the Sprague Dawley rat.

Although there has been a 40% decrease in use of labora-tory animals since 1968, rats, mice, and other rodents makeup 85 to 90% of animals used in biomedical research (1). An-esthetic agents not only play an important part in genera-tion of repeatable research results but also may influenceinterpretation of research data. Although anesthetic selec-tion is an integral component in prevention and alleviationof pain associated with procedural and surgical protocols, italso reflects professional judgment as to which agent bestaddresses clinical, scientific, and humane concerns (2). Ap-propriate anesthetic selection not only requires knowl-edge about the anesthetic agent and the best routes ofadministration, but also requires knowledge about re-sponses that are typical for the animal subject.Tribromoethanol (TBE) has been widely used as a surgi-cal anesthetic in transgenic mouse development despite con-tinuing controversy about its safety and side effects (3–5).Using TBE as a surgical anesthetic in mice, Papaioannouand Fox (6) documented low rate of mortality, adhesions, orinflammatory responses. Gardner et al. encountered a highdegree of variability in induction time and a short period ofadequate anesthesia with use of TBE in mice (7). Othershave reported that high mortality was associated with TBEuse in rodents (3–5, 8). In the rat, TBE is recommended at adosage of 260 to 300 mg/kg of body weight given intraperito-neally (i.p.), but is thought to occasionally cause fibrous ad-hesions and intestinal ileus (3, 4). Little evidence has beengained from controlled studies that substantiate TBE as anacceptable anesthetic agent in the rat. In the study reportedhere, TBE was given to female Sprague Dawley rats to de-termine whether pathologic changes were induced by i.p.administration of a low dosage (200 mg/kg), a therapeuticdosage (300 mg/kg) or a high dosage (400 mg/kg). Gross andmicroscopic data were collected and are presented here.This study was approved by the Institute of Human Virol-ogy Animal Care and Use Committee. Twenty-five maturevirus antibody-free Sprague Dawley female rats (