Anti–Müllerian hormone concentrations in queens throughout the estrous cycle

Studies in cats and dogs have proven the usefulness of anti–Müllerian hormone (AMH) as a diagnostic tool to determine the castration status or to diagnose ovarian remnant syndrome. Yet the secretion pattern of AMH over the estrous cycle in queens has not been investigated so far. Seven healthy sexually intact female cats were examined daily for signs of estrous behavior over a trial period of 4 months. Five queens showed regular estrous behavior, 1 queen was mated in her first heat and 1 queen never showed any signs of heat. To distinguish between inter–estrus and metestrus progesterone levels were determined. Serum samples for AMH and progesterone measurement were collected from the regular cycling queens in late anestrus, at several times during heat, inter-estrus and metestrus, from the mated queen during her first heat and during pregnancy, and in the acycling queen at various times during the trial period. The measured AMH values in anestrus were significantly (P < 0.05) higher than in heat (P < 0.001), metestrus (P = 0.12) and inter–estrus (P = 0.449). In anestrus the median AMH levels were 10.26 ng/ml (range 4.96 to 22.90 ng/ml), in heat 5.97 ng/ml (range 3.32– 22.96 ng/ml), in inter–estrus 10.47 (range 3.35–22.96 ng/ml) and in metestrus 6.38 ng/ml (range 4.50–10.75 ng/ml. The pregnant cat showed median AMH concentrations of 6.47 ng/ml (range 5.60–9.80 ng/ml) during her pregnancy. The acycling queen had solely low AMH values with a median concentration of 0.39 ng/ml. In conclusion there were high variations of the AMH levels among and within the individual cats and between heat cycles in the single cat. Remarkable high AMH concentrations were measured in the younger queens of the study in their first estrous cycles and also in anestrus, when less ovarian activity is expected. Further studies are necessary to emphasize the reasons for these high AMH concentrations especially in young queens.