| Abstract: | The main objective of this study was to compare the effects of ketamine and xylazine in
aging rats when coadministered intraperitoneally at high anesthetic doses. Three groups
(n=6 rats/group) consisting of rats at 3, 6 and 12 months of age were used. During
anesthesia, animals were monitored for heart rate, respiratory frequency, blood oxygen
saturation, and rectal temperature. The corneal and paw withdrawal reflex were also
examined during anesthesia. During anesthesia, withdrawal and corneal reflexes were absent
for progressively longer durations with increasing age. Significant decreases in cardiac
and respiratory frequency and, blood oxygen saturation occurred for the 6- and
12-month-old animals. Respiratory frequency and blood oxygen saturation returned to normal
at the end of the anesthesia; however, the significant decrease in cardiac frequency
persisted in the 6- and 12-month-old animals. Rectal temperature was decreased
significantly only in the 3-month-old animals. Pulmonary edema and effusion occurred in
50% of the 12-month-old animals. In conclusion, if ketamine-xylazine are used for
anesthesia, the doses should be optimized for the age of the subjects prior to initiation
of the research project. |
