Spontaneous congenital developmental abnormalities observed at necropsy in a large survey of newly born dead lambs

Abstract

In a systematic necropsy study of 4408 newly born dead lambs derived from 79 flocks over two lambing seasons malformation considered sufficient to impair viability was observed in 80 carcasses. Agnathia was observed in 25 carcasses and comprised the major component of congenital lethal malformations. Lambs of both sexes were affected. Its occurrence was often associated with anotia, ear displacement, or ear malformation. Factors thought to be associated with this abnormality are reviewed and attention drawn to the lack of knowledge concerning the embryonic development of the first branchial arch and related structures in sheep. Developmental defects of the muscular and skeletal systems, central nervous system, cardiovascular system (particularly ventricular septal defects), and imperforate intestinal tract were the next most common malformations.

Anthelmintic induced congenital malformations in sheep embryos using netobimin

“…The incidence of lethal congenital malformations in lambs is 0·2 to 0·3 per cent (Hughes and others 1972), even though congenital defects can affect up to 2 per cent of newborn lambs. Since they are caused by genetic and environmental factors, the frequency and total number of individual defects vary with breed, geographic area, year, sex, parental age and level of nutrition (Dennis and Leipold 1979).…”

“…Congenital renal defects are uncommon in sheep (Angus 1990), although hydronephrosis and cystic or polycystic kidneys have been recorded (Hughes and others 1972, Dennis and Leipold 1979, Angus 1990).…”

“…Congenital vascular anomalies, excluding cardiac anomalies, are rare in lambs (Hughes and others 1972, Dennis and Leipold 1979), although some spontaneous vascular malformations have been described in sheep (Dominguez and others 1993). No teratological studies with benzimidazole compounds have reported vascular anomalies.…”

A Case History of Gross and Radiological Observations of Agnathia: Otocephaly in a Mehraban Ewe-lamb

“…Pursuant to classification, breeds of sheep, and grade of agnathia, this malformation in sheep differs amidst the reported studies. In 1972, on scrutiny of spontaneous congenital defects in Merinos breed herds, 25 cases of agnathia (31% deadly anomalies) were detected in 80 lifeless carcasses of newborn lambs (Hughes et al, 1972). According to the study of Dennis and Leipold (1972), in Western Australia, over 3 years, 401 deformed lambs were evaluated, and 74 cases of diverse forms of agnathia (18.3% lethal defects) were recorded.…”

Intestinal Atresia and Stenosis in Animals: A Report of 34 Cases

“…There were 17 in the calf [8,16,17,23,32,41], five in the lamb [lo, 15,22,24,38], and two in the pup [19,28]. Atresia or stenosis of the large intestine has been described in 202 animals: 40 cases in foals [2,7,11,33,47] and 162 in calves [3,4,14,18,20,23,29,30,36,37,39,40,41].…”