Histomorphometric comparison of the corpus cavernosum of rats submitted to euthanasia with ketamine and xylazine or isoflurane

PURPOSE: To compare the penile histoarchitecture of rats euthanized with isoflurane or with ketamine and xylazine. METHODS: Fourteen male rats were divided into two groups: ISO, with animals euthanized with isoflurane; and K+X, with animals euthanized with ketamine (150 mg/kg) associated with xylazine (15 mg/kg). Immediately after the death, the penises were dissected, fixed in a 4% buffered formalin solution, and processed for histomorphometric analysis. The surface densities (Sv) of the corpus cavernosum structures (connective tissue, smooth muscle, sinusoidal space, and elastic fibers) were evaluated using Image J software. The distribution of collagen types I and III was qualitatively assessed. Statistical analyses were performed using the Student’s t test for data comparison, considering it statistically significant when p < 0.05. RESULTS: Regarding the Sv of connective tissue, smooth muscle and sinusoidal space, there were no differences between animals in both groups. On the other hand, the animals euthanized with the association of ketamine and xylazine showed the Sv of elastic fibers 24.8% higher in relation to animals euthanized with isoflurane. CONCLUSIONS: The euthanasia method affected one of the morphological parameters of the rat penises. The choice of euthanasia method must be standardized to reduce bias and to obtain reliable and reproducible results.