Incidence risk and clinical features of retention of foetal membranes in ewes in 28 flocks in southern Greece

Abstract

In a field investigation of 28 flocks in southern Greece, 7660 lambings were monitored. Retention of foetal membranes (defined as failure to expel the foetal membranes within 6 h of lambing the last lamb) was recorded in 92 ewes. The median within-flock incidence risk was 1.25% (range: 0–1.9%). The heterogeneity of the risk among flocks was not significant ( p = 0.99); no correlation was found between the incidence risk and the flock size ( r sp = 0.33, p = 0.09). Overall, the median duration of retention was 72 h (range: 9–288 h); it did not differ among flocks ( p = 0.89) and was not correlated with flock size ( r sp = 0.24, p = 0.27). During the initial stage of retention the membranes were fleshy and humid; the cotyledons were thick and congested. Progressively, the membranes became thin, dry and stringy; the cotyledons shrunk and were pale. Finally the membranes dropped as a mass. In ewes with retention for >12 h, a variety of accompanying signs was recorded: straining (in 22% of the ewes with retention), vulval oedema and reddening (in 16%), anorexia (in 13%), recumbency (in 13%) and increased temperature (in 12%) were the most frequent ones. Overall, the median clinical score of the disorder was ‘2’ (range: ‘1’–‘5’); it did not differ among flocks ( p = 0.98) and was not correlated with flock size ( r sp = 0.26, p = 0.25). In 4% of the ewes with retention for <4 days accompanying signs were recorded (median clinical score: ‘2’), whilst in 80% of the ewes with retention for ≥4 days accompanying signs were recorded (median clinical score: ‘3’). This difference in the prevalence of clinical signs was significant ( p < 0.0001).