Perinatal lamb mortality in Western Australia. 7. Congenital defects.

Four hundred and one malformed lambs were examined during a 3-year investigation into the causes of perinatal lamb mortality. Frequence of involvement of the various body systems was: musculo-skeletal 55.4%, digestive 12.7%, cardiovascular 9.7%, uro-genital 7.1%, nervous 6.0%, special senses 3.5%, integument 3.2%, and endocrine 1.5%. A third of the defects (32.9%) involved more than one body system. There was a sex difference of 3 males: 2 females. The common defects in the lambs autopsied in order of frequence were: agnathia, atresia ani, cardiac defects, arthrogryposis, micrognathia, scrotal bifurcation, embryonic duplications, hernias, meningocele, and perosomus elumbis. Agnathia, atresia ani and persistent umbilical haemorrhage appeared to be hereditary. There was no relationship between congenital defects and the time of lambing and phytoestrogens.