Effects of Electroejaculation and Ketamine‐HCl on Serum Cortisol, Progesterone, and Testosterone in the Male Cat

The influence of manual restraint, ketamine‐hydrochloride anesthesia and electroejaculation under anesthesia on circulating levels of cortisol, progesterone and testosterone was examined in male domestic cats. In the first experiment, cats were anesthetized with ketamine‐HCl (17.5 mg/kg of body weight) and serially bled (controls) or serially bled and electroejaculated. These animals showed signs of recovering from anesthesia within 45 to 60 minutes of ketamine‐HCl injection. Average serum cortisol concentrations increased (P < 0.01) over the 84‐minute sampling interval in both the electroejaculated and control groups. Cortisol levels reached their maximum concentration in the electrically stimulated males immediately postelectroejaculation (95.1 ng/ml) and were significantly greater (P < 0.01) than in the controls (36.1 ng/ml) at a comparable time. Maximal mean cortisol concentrations in the control group (62.8 ng/ml) occurred 54 minutes after the first blood sample and occurred together with the onset of anesthesia recovery. Mean testosterone levels did not differ between electroejaculated and control cats, but did decrease (P < 0.05) between the first and last blood sampling in both groups. In the second experiment, cats were bled on the same time schedule as in Experiment 1, but were bled while awake and manually restrained, or else during a deeper plane of anesthesia induced and maintained with higher doses of ketamine‐HCl (initial dose, 23 mg/kg). Mean serum cortisol levels were greater (P < 0.05) during manual restraint (range, 36.3–41.1 ng/ml) compared to deep anesthesia (range, 16.7–25.8 ng/ml), but did not change over the 84 minute sampling interval in either group. Although the decline in mean concentrations was not significant, testosterone decreased by 31–94% in four of six individual males during both manual restraint and deep anesthesia. Serum progesterone levels in both Experiments 1 and 2 averaged less than 0.5 ng/ml. Although progesterone increased (P < 0.05) between the first and last blood samples in Experiment 1, the absolute quantities detected were indistinguishable from possible progesterone antibody cross‐reactivity with the hormone cortisol. The results of this research indicate that electroejaculation of the anesthetized cat produces acute stress as demonstrated by elevated serum cortisol levels measured immediately after electroejaculation. However, significant increases in cortisol also are detected in non‐electroejaculated cats recovering from ketamine‐HCl anesthesia. Such a rise is abolished if males are maintained under a more prolonged and deeper plane of anesthesia during blood sampling, or if no ketamine‐HCl is given. Because serum testosterone declines markedly in most cats independent of a detectable rise in cortisol there is no clear, physiological coupling of these two hormones in this species. 1984 American Society of Andrology