Why do ewes prolapse

Overview

Ewe prolapse, specifically vaginal or uterine prolapse, is a significant reproductive disorder in sheep farming that has been documented since the early 20th century. The condition involves the protrusion of reproductive tissues through the vulva, most commonly occurring during late pregnancy or around lambing time. Historical records from veterinary journals in the 1920s show that prolapse was recognized as a serious complication even in early commercial sheep operations. The condition gained particular attention in the 1970s with the expansion of intensive sheep farming systems, where incidence rates were observed to increase. Today, it remains a concern worldwide, with regional variations in prevalence - New Zealand and Australia report some of the highest rates due to their large sheep populations and intensive management systems. The economic impact is substantial, with affected ewes showing reduced productivity and higher mortality rates.

How It Works

Ewe prolapse occurs through a combination of mechanical and physiological factors. During late pregnancy, the increasing weight of the uterus and developing lambs creates downward pressure on pelvic structures. Hormonal changes, particularly elevated estrogen levels, cause relaxation of pelvic ligaments and connective tissues. This combination can lead to weakening of the vaginal support structures. When ewes strain during defecation or urination, or when lying down, the increased intra-abdominal pressure can force the vaginal tissue to evert through the vulva. The prolapse typically begins as a small pink mass that progressively enlarges, becoming edematous and potentially necrotic if left untreated. In uterine prolapse, which occurs immediately after lambing, the entire uterus may invert and protrude. The condition is self-perpetuating - once tissues become exposed, they swell further, making spontaneous reduction impossible without intervention.

Why It Matters

Ewe prolapse has significant economic and welfare implications for sheep producers worldwide. Financially, affected ewes have reduced productivity - studies show a 15-25% decrease in subsequent lambing rates and lower weaning weights for lambs from recovered ewes. The condition accounts for approximately 3-5% of ewe mortality in commercial flocks, representing substantial losses. From an animal welfare perspective, prolapsed ewes experience pain, stress, and increased susceptibility to infection and predation. The condition also affects flock management, requiring additional labor for monitoring and treatment. Prevention through proper nutrition, body condition scoring, and selective breeding has become a focus of modern sheep management programs. Research continues into genetic markers associated with prolapse susceptibility, offering potential for breeding more resilient flocks in the future.