Background:The mechanisms of ischemia and reperfusion in intestinal strangulation have been extensively studied in horses; however, most intestinal strangulation cases in horses are characterized by venous strangulating obstruction. As demonstrated in other species,blood sequestration results from venous strangulation, and results in blood loss when the intestine is resected, with potential consequences for the metabolic and physiological state of the animal. Objectives: Aim of this study is to evaluate the extent of blood sequestration in horses with clinical strangulated small intestinal obstruction and propose a new classification for small intestinal pathologies. Study Design: case-control study Methods:The study included horses submitted to euthanasia and with strangulating small intestinal obstruction diagnosed at necropsy. Blood sequestration was measured by evaluating the weight of affected bowel segments and calculating the volume of blood sequestrated per meter of strangulated intestine. Difference in weight between strangulated and normal segments was compared. Results: The weight of the strangulated small intestine was significantly different from the weight of normal intestine. (p<0.0001) On average, approximately one liter of blood was sequestered per meter of strangulated intestine. Main Limitations: The study did not account for all compartments where blood sequestration occurs, including the intraluminal and intraperitoneal spaces, thus the blood loss may be underestimated. The study was limited to grade 3-4 lesions. Conclusions: The findings confirm that significant blood sequestration occurs in strangulated intestinal segments, which can lead to substantial blood loss when resection is performed. These findings emphasize the need for careful assessment of intestinal viability during surgery to prevent unnecessary resection and improve prognosis classification in light of these results is provided. Clinical relevance: significant blood sequestration occurs in strangulated intestinal segments, which can lead to substantial blood loss when resection is performed. careful assessment of intestinal viability during surgery to prevent unnecessary resection and improve prognosis is paramount.

Background: Volvulus nodosus is a strangulating lesion of the small intestine described only in foals and in just one case in older horses. Huskamp et al (1982, 1998) described the pathophysiology of volvulus nodosus in foals, but to date there is no description of the pathophysiology of volvulus nodosus in adults. Objectives: to describe the different features of volvulus nodosus in adult horses and in foals. Study design: Clinical case series. Methods: Analysis of the clinical and anatomical features of 2 foals and 3 adults presenting with volvulus nodosus. Results: Clinical presentation between foals and adults differed mainly for the mild or absent pain showed by older horses. Clinical and ultrasonography findings were similar. At surgery or necropsy we found anatomical differences between adults and foals. In adults the volvulus didn’t involve the mesentery that instead forms a hernia sac in foals. Further, in adults, there wasn’t involvement of the ileum, but two loops of jejunum resulted one wrapped around another in all 3 cases. After accurate analysis of one case at necropsy, we found that in adults one loop act as a “post” around which another loop turns around. The weight of this loop causes then the formation of a half-hitch formed by the two loops and their mesentery. This cause strangulation and necrosis of two separate tract of jejunum. Main limitations: Small number of cases included. Conclusions: Volvulus nodosus may occur in adult horses with significant differences compared to foals. Knowing the presentation and pathophysiology of volvulus nodosus may help equine surgeons to resolve selected cases of small intestinal strangulation in adult horses.