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OBJECTIVE: To define cyclic changes in anti-Mollerian hormone (AMH), inhibin-B, and progesterone concentrations and establish statistically valid, population-based clinical reference ranges in queens. ANIMALS: Cyclic queens (fertile, n = 6; infertile, 6) from an institutional breeding colony were blood sampled longitudinally, each for over 2 months, between November 2021 and February 2022, and residual serum samples from intact (n = 205) and ovariohysterectomized (49) queens from clinical submissions were used to establish reference ranges for intact and spayed females. METHODS: AMH and inhibin-B were measured using commercially available ELISAs, progesterone was measured using an inhouse ELISA, and 90% Cls were calculated from these data. RESULTS: AMH and inhibin-B fluctuated in a highly correlated, cyclic pattern in 3 queens that did not ovulate immediately, whereas AMH declined as progesterone increased, indicative of ovulation, which occurred spontaneously early in the sampling period in 3 others; statistically valid reference ranges were established in intact and ovariohysterectomized females. CLINICAL RELEVANCE: Cyclic changes in hormone profiles were defined, providing relevant context for interpreting results in cases seeking to determine gonadal status (presence or absence of gonadal tissue) on the basis of established, population-based reference ranges reported here for cats for the first time. [ABSTRACT FROM AUTHOR]

Objective: To establish statistically valid, population-based reference intervals (RIs) for canine anti-Müllerian hormone (AMH) and define changes in AMH and inhibin-B in bitches during breeding cycles., Methods: A homologous canine ELISA was used to measure AMH in serum samples (collected between May 2019 and July 2024) from 102 intact and 78 reportedly ovariohysterectomized (OVH) bitches and 8 bitches before and after ovariohysterectomy, and in longitudinal samples from 24 bitches undergoing breeding management. Established 95% RIs were used in a retrospective assessment of 3,193 clinical submissions. Cyclic variation of AMH and inhibin-B (heterologous ELISA) were regressed with time and normalized to the rise in progesterone in samples from breeding bitches., Results: Intact and OVH RIs for AMH were calculated with and without inclusion of 7 samples from reportedly OVH bitches that had AMH concentrations in the intact RI. Anti-Müllerian hormone and inhibin-B were positively correlated, and AMH was 3 times higher in proestrus than in estrus. Retrospectively, of 3,193 samples submitted for clinical AMH testing, 41% to 56% were in or above the intact AMH interval, 37% to 44% were within the OVH interval, and < 10% were inconclusive, depending on how RIs were defined., Conclusions: Statistically valid, population-based RIs establish a sound basis for interpreting results of clinical submissions requesting AMH to assess gonadal status in the bitch., Clinical Relevance: Confirmation of cyclic variation in AMH (and, for the first time, inhibin-B) reaffirms proestrus as the optimum time to draw samples, and ≤ 10% of samples submitted for determination of gonadal status are expected to fall in an inconclusive AMH RI.