Non-invasive faecal steroid monitoring of ovarian and adrenal activity in farmed blue fox ( Alopex lagopus) females during late pregnancy, parturition and lactation onset

Abstract

In the semi-domesticated blue fox, handling stress may influence reproductive performance and increase perinatal pup loss. Ovarian and adrenal steroids were analysed in faecal samples collected from mid-gestation through the first week of lactation in 40 female blue foxes to characterize hormone patterns during this important reproductive period. Daily faecal samples were collected from 40 foxes during 30 pregnancies, one late abortion and nine bred-matched non-pregnancies. Mean concentrations of faecal progestagens over the 10 days before birth were significantly higher in pregnant compared to non-pregnant females (51 ± 1.50 μg/g versus 36 ± 3.72 μg/g, respectively; P < 0.01). From 10 to 3 days before whelping, total faecal oestrogen concentrations also were higher ( P < 0.01) in pregnant (1082 ± 41.69 ng/g) than non-pregnant (628 ± 72.43 ng/g) foxes, before declining to non-pregnant values (402 ± 24.88 ng/g) after parturition. Overall mean faecal corticoid concentrations from 3 to 20 days before whelping differed between pregnant and non-pregnant foxes (128 ± 3.11 ng/g versus 103 ± 5.86 ng/g, respectively; P < 0.01). Furthermore, in pregnant foxes, corticoid excretion increased further from 2 days before to 3 days after whelping (216 ± 13.71 ng/g; P < 0.01). Thereafter, corticoid concentrations were similar between pregnant and non-pregnant females ( P > 0.05). In sum, the faecal steroid hormone patterns for oestrogens and progestagens were similar to those previously obtained by analyses of fox serum hormones, with both steroids being higher in pregnant than non-pregnant foxes at the end of gestation. The elevation in corticoid concentrations in pregnant females suggests that adrenal activation is involved in the initiation of parturition in the blue fox. Thus, faecal steroid analyses can be used to monitor ovarian activity during pregnancy and pseudopregnancy in farmed blue fox females.