Effect of intraluminal distention on microvascular perfusion in the equine small colon

Rafael R. Faleiros Department of Veterinary Clinic and Surgery, Escola de Veterinária da UFMG, CP 567, CEP 30161- 970, Belo Horizonte, MG, Brazil.

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Delphim G. Macoris Department of Veterinary Clinic and Surgery Faculdade de Ciências Agrárias e Veterinárias, São Paulo State University, Via de Acesso Paulo Donato Castellane, Km 5, Jaboticabal, SP, Brazil, CEP 14884-900.

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Antonio C. Alessi Department of Animal Pathology, Faculdade de Ciências Agrárias e Veterinárias, São Paulo State University, Via de Acesso Paulo Donato Castellane, Km 5, Jaboticabal, SP, Brazil, CEP 14884-900.

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Carlos H. C. Saquetti Department of Veterinary Clinic and Surgery Faculdade de Ciências Agrárias e Veterinárias, São Paulo State University, Via de Acesso Paulo Donato Castellane, Km 5, Jaboticabal, SP, Brazil, CEP 14884-900.

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Luciane Rasera Department of Veterinary Clinic and Surgery Faculdade de Ciências Agrárias e Veterinárias, São Paulo State University, Via de Acesso Paulo Donato Castellane, Km 5, Jaboticabal, SP, Brazil, CEP 14884-900.

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Abstract

Objective—To determine the effect of experimental intraluminal distention on microvascular perfusion of the small colon in horses.

Animals—6 mixed-breed healthy horses (mean age [± SD], 9.1 ± 2 years).

Procedure—Under general anesthesia, the small colon was exposed by celiotomy and 3 segments were demarcated. In 1 of these segments, intraluminal obstruction was created by placement of a latex balloon inflated to a pressure of 40 mm Hg (obstructed segment). The other segments were the sham-operated segment and the control segment. Microvascular perfusion was evaluated in the mucosal, submucosal, muscular, and serosal layers by injection of 15-µm-diameter colored microspheres into branches of the caudal mesenteric artery. Recovery of microspheres was performed by tissue digestion, washing, and centrifugation. Distribution of microspheres in the intestinal layers was evaluated by direct observation of stained frozen sections by light microscopy.

Results—A significant reduction was observed in total microvascular perfusion of obstructed segments, which was 26.4% of that of control segments. This reduction was not evident in the mucosal layer.

Conclusion and Clinical Relevance—Intraluminal distention of the equine small colon wall can promote ischemia by a reduction in microvascular perfusion in the intestinal wall. Intestinal layers do not seem to be affected to the same extent, because the absolute value for mucosal perfusion did not decrease in the obstructed segment. (Am J Vet Res 2002;63:1292–1297)

Abstract

Objective—To determine the effect of experimental intraluminal distention on microvascular perfusion of the small colon in horses.

Animals—6 mixed-breed healthy horses (mean age [± SD], 9.1 ± 2 years).

Procedure—Under general anesthesia, the small colon was exposed by celiotomy and 3 segments were demarcated. In 1 of these segments, intraluminal obstruction was created by placement of a latex balloon inflated to a pressure of 40 mm Hg (obstructed segment). The other segments were the sham-operated segment and the control segment. Microvascular perfusion was evaluated in the mucosal, submucosal, muscular, and serosal layers by injection of 15-µm-diameter colored microspheres into branches of the caudal mesenteric artery. Recovery of microspheres was performed by tissue digestion, washing, and centrifugation. Distribution of microspheres in the intestinal layers was evaluated by direct observation of stained frozen sections by light microscopy.

Results—A significant reduction was observed in total microvascular perfusion of obstructed segments, which was 26.4% of that of control segments. This reduction was not evident in the mucosal layer.

Conclusion and Clinical Relevance—Intraluminal distention of the equine small colon wall can promote ischemia by a reduction in microvascular perfusion in the intestinal wall. Intestinal layers do not seem to be affected to the same extent, because the absolute value for mucosal perfusion did not decrease in the obstructed segment. (Am J Vet Res 2002;63:1292–1297)

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