Schistosoma reflexus.
Keywords: dystocia, shistosoma, reflexus, bovine
Image size: 2500 x 1339 px
An image of female schistosoma reflexus beef (SR) calf. The hind legs are reflected over the head as shown and the viscera are totally exposed. Schistosoma (or closely related syndromes) occur in most mammals, including humans but it is only in ruminants that the total reflection of the limbs and body occur frequently. In other species, the body wall is often split (schistosoma) but the body is seldom reflected (reflexus).
SR is a defect resulting from incomplete folding of the embryo after embryonic folding. This excellent animation shows the "folding" process in a human embryo. If you have a veterinary or animal science background, you will find it interesting to see the allantois vanish in that animation.
Fairly recent data (see references) suggest that SR is a heritable defect, caused by an abnormal autosomal recessive gene. In one study, the occurrence of SR occurred at a frequency of about 1% in about 7000 cases of dystocia. Interestingly 60% of those cases were resolved y fetotomy, 25% by cesarean section and 3% by mutation and traction. The remainder were euthanized. Others have reported lower incidence of SR than 1%
Selected references
Citek, J. 2012 Pedigree analysis of Czech Holstein calves with schistosoma reflexum. Acta Vet. Scand. 54:22
Knight, R.P. 1996. The occurrence of schistosomus reflexus in bovine dystocia. Australian Vet. J. 73: 105–107
Laughton K.W. et al 2005, Schistosomus Reflexus Syndrome: A Heritable Defect in Ruminants Anat. Histol. Embryol. 34: 312–318
