Situs ambiguus in a Brown Swiss cow with polysplenia: case report

摘要

Background Laterality defects are rare in cattle and usually manifest as asplenia orpolysplenia syndrome. These syndromes may be associated with situs ambiguus,which is a dislocation of some but not all internal organs. The objective ofthis report was to describe the clinical and post-mortem findings includingthe macroscopic and microscopic anatomy of selected organs in a cow withpolysplenia and situs ambiguus. Case presentation A 3.5-year-old Brown Swiss cow was referred to the Department of FarmAnimals, Vetsuisse Faculty, University of Zurich, because of poor appetiteand recurrent indigestion. A diagnosis of situs ambiguus was based on theresults of physical examination, ultrasonography, exploratory laparotomy andpost-mortem examination. The latter revealed that the rumen was on the rightside and lacked compartmentalisation. There were two spleens, one on theleft (26.5 x 12.0 cm) and one on the right (20.5 x 5.5 cm), and the omasumwas located craniolateral to the ruminoreticulum on the left. The abomasumwas located on the right, although it had initially been displaced to theleft. The three-lobed liver occupied the left and central cranioventralaspect of the abdominal cavity (cavum abdominis). Only the right and lefthepatic veins (vena hepatica dextra and sinistra) drained into the thoracicsegment of the caudal vena cava (vena cava caudalis), and histologicalchanges in the liver were indicative of impaired haemodynamics. Themesojejunum was not fused with the mesentery of the spiral loop (ansaspiralis) of the ascending colon (colon ascendens). The latter was foldedand the transverse colon (colon transversum) ran caudal to the cranialmesenteric artery (arteria mesenteria cranialis). Fibrotic constrictionswere seen in the lumen of the caecum and proximal loop (ansa proximalis) ofthe ascending colon. Both kidneys were positioned retroperitoneally in alumbar position. The lumbar segment of the caudal vena cava did not descendto the liver and instead drained into the right azygous vein (vena azygosdextra). Conclusions Recurrent digestive problems and poor production in this patient may havebeen caused by a lack of rumen compartmentalisation, abnormal abomasalmotility, constrictions in the large intestine (intestinum crassum) andfibrosis of the liver. The abomasum had abnormal motility most likelybecause it was anchored inadequately and only at its cranial aspect to theliver by the lesser omentum (omentum minus) and to the dorsal abdominal walland rumen by a short greater omentum (omentum majus).