Riding on each other in rabbits (Oryctolagus cuniculus) cannot be clearly assigned to the sexual behavioural repertoire but can also be shown in the case of ambiguity in the group rank order¹ or in the presence of adrenocortical disease².
In dogs and cats Anti-Müllerian-Hormone (AMH) determination is a common diagnostic procedure in cases of unclear castration or suspected cryptorchidism or ovarian remnant syndrome⁴.
However, reference values are missing for rabbits until now.
In a retrospective study, serum samples sent in from 142 rabbits over the last 12 months, were analysed. AMH was determined using the chemiluminescence immunoassay (Access 2, Beckman Coulter). The test system is validated for human AMH measurement.
The AMH values of female intact rabbits ranged from 0.37 to 4.92 ng/ml (median: 1.61 ng/ml). In 22 female castrated animals, the AMH value of ≤ 0.03 ng/ml was clearly below the value of the intact animals.
The AMH values of male intact rabbits ranged from 1.56 to 153.09 ng/ml (median: 32.10 ng/ml). In 53 male castrated animals, the AMH value of ≤ 0.02 ng/ml was clearly below the value of the intact animals.
As cut-off values for a complete castration in female rabbits were AMH values ≤ 0.03 ng/ml determined, and in completely castrated males ≤ 0.02 ng/ml. This allows a simple determination of animals with unclear castration status. The presence of cryptorchidism could also be confirmed by laboratory diagnostics. Regarding the ovarian remnant syndrome, corresponding cases were lacking, but it was suspected in one case.