Endocrinological and sonographical diagnosis of pregnancy in alpine marmots (Marmota marmota). [Diagnose endocrinologique et sonographique de la grossesse chez les marmottes alpines].

Résumé

Under natural and artificial conditions alpine marmots are true hibernators with a single breeding season following the emergence from hibernation. In captive marmots a continuous investigation of mating and breeding is possible. Eight colony housed adult female marmots with a weight between 2.4 kg and 3.2 kg were examined. The sutdy started 2 days after hibernation and lasted till the end of pregnancy. Twice weekly blood samples were taken (progesterone assay) and ultrasound investigations were performed, as well. Body weight of the females during gestation and of the puppies at birth were monitored. Four animals became pregnant which was proven by ultrasound diagnosis in all cases. The first positive findings of amniotic sacs dated at day 9 of gestation, while the embryos itself were found at day 14. Two days later (day 16) pulsation of the embryonic heart was detectable. After 34 days of gestation the females gave birth to 12 living puppies. The birth weight of the young and healthy marmots ranged from 23.4 to 31.8 g. Progesterone peak values in non pregnant females were almost half (8.43 ± 0.48 nmol/l mean ± sem) of those seen in pregnant ones (15.5 ± 1.15 nmol/l). The hormone values obtained during the second week of pregnancy (12.4 ± 0.9 nmol/l) were significantly higher as in non pregnant animals (8.76 ± 0.65 nmol/l p< 0.01). Two females showed constant progesterone levels below 0.36 nmol/l without a detectable peak. This led to the conclusion that these marmots showed non cycles. We conclude that the ultrasonographic examination of pregnancy in alpine marmots is possible in a rather early stages of gestation. Additional simultaneous analysis of serum progesterone content allows for a clear diagnosis of pregnancy already from the second week of gestation.