Cardiomyopathy in adult Holstein Friesian cattle in Britain.

The clinical signs, pathology and breeding data of two cases of cardiomyopathy of an unusual kind in adult Holstein Friesian cattle in Britain are reported and compared with those in similar entities in Switzerland, Japan and Canada. The principal and primary lesions affect the heart and these produce secondary changes, particularly in the liver, and result in fatal congestive heart failure. The cardiac lesions consist of extensive myocyte vacuolation, endomysial and perimysial fibrosis and focal cardiac myocyte degeneration, atrophy and hypertrophy resulting in an extended range of myocyte size. Lesions affected all four heart chambers but were most severe in the ventricles. Vascular lesions, particularly moderate medial hypertrophy and intimal thickening of arterioles and arteries, occurred in heart, lung, kidney and lymph nodes. The liver showed severe fibrosis, chronic congestion and hepatocyte loss. There was a chronic multifocal nephritis. The cause is unknown, but the affected animals were full brother and sister and have a common ancestor in the male and female line five generations earlier.

A vertically transmitted cystic renal dysplasia of lambs.

A new form of bilateral renal dysplasia in lambs appeared in a commercial sheep flock in 1982. The nature of the problem, the field investigations and the laboratory examinations carried out over three lambing seasons are described. It was concluded that the condition was vertically transmitted and genetic in origin. During the two years that accurate records were kept approximately 30 per cent of the suspected ram's progeny died with lesions of renal dysplasia. The condition recurred during a breeding trial in progeny from one of the two commercial rams originally used on the farm. An autosomal dominant mode of inheritance is suggested. The incidence illustrates the importance of keeping breeding records, especially when several rams are maintained in a flock, and the value of examining a large number of lambs post mortem.

Estimation of the developmental age of the bovine fetus and newborn calf.

Jersey cows from several herds provided 97 fetuses and 24 calves at fixed gestational intervals between 80 and 290 days after conception. The fetuses and calves were killed, weighed and measured and, after dissection, the sizes and weights of a range of skeletal and soft tissues were recorded. Six morphological measurements emerged as most suitable for the determination of developmental age in the normal fetus. By plotting their mean values and 95 per cent tolerance limits, the rates of growth and the variability of each measurement were defined. Long bone length was the most useful single measurement for predicting the developmental age of the fetus. Brain weight, bodyweight, crown-anus length and long bone length showed curvilinear growth patterns; age prediction equations derived from these measurements are complicated to use and additional simplified formulae have been derived. The number of appendicular ossification centres also had predictive value, but it could not be used to determine fetal developmental age between 100 and 160 days gestation.

A study of the inheritance of susceptibility to bovine spongiform encephalopathy.

A genetic study of 75 cases of bovine spongiform encephalopathy (BSE) of which 51 were confirmed by histopathology in 29 pedigree and seven non-pedigree herds of Holstein Friesian cattle revealed that 73 per cent of 60 BSE cases had first or second degree relatives also affected. All the 44 cases assigned to families could be traced back in the previous three generations to one cow and 11 bulls, which were of Canadian Holstein or Dutch Friesian heredity. No single common ancestor could be identified in the parentage of BSE-affected animals in pedigree studies up to six or more generations. The number of common ancestors and the degree of relatedness of the affected animals in a multiple-case herd was no more than would be expected from the breeding structure of the herd. The segregation ratio of affected cows in the proband generation within sire and maternal grandsire sibships in 12 pedigree herds was not inconsistent with Mendelian expectation for autosomal recessive inheritance with complete penetrance. The data analysed shows that the disease itself is not simply inherited. However, there remains a real possibility that the susceptibility of individual animals to BSE is inherited. This should be taken into account in current and future research on the aetiology and control of the disease.

A genetic, pathological and virological study of congenital hypotrichosis and incisor anodontia in cattle.

Two Friesian cows, half-sibs by a common dam, produced four bull calves with severe congenital hypotrichosis and incisor anodontia and three normal heifers by six unrelated Holstein, Friesian, Devon and Hereford bulls. The two dams, and their dam, had coats of a short, stubbly nature and the pigmented areas appeared rusty grey rather than black. Pathological examination of skin samples taken from multiple standardised sites from two of the affected calves showed a reduction in the number of large first-formed hair follicles. Smaller calibre hair follicles were present but, unlike those of normal neonatal calves, all were in the telogen (inactive) phase. Although the herd was infected with bovine virus diarrhoea virus there was no convincing evidence that the virus was implicated in the pathogenesis of these cases of congenital hypotrichosis with incisor anodontia. The family breeding information on the few severely affected and normal progeny and mildly affected and normal parents may be explained by the genetic hypothesis of an X-linked incompletely dominant gene.

Reproductive anatomy and cytogenetics of freemartin heifers.

Out of a batch of 46 heifers obtained for breeding 19 were found to be freemartins by both anatomical and cytogenetic examination. Considerable variation existed in the reproductive tracts of these freemartins from structures that were essentially female to some that were essentially male in type. One heifer had a functional ovary containing a corpus luteum and had shown signs of oestrus. Sex chromosome chimaerism was detected in cultured leucocytes and in bone marrow from each of the freemartins, ranging from 2 per cent to 96 per cent male cells. Chimaerism was also detected in cell cultures from spleen, lung and gonad but at very low levels (less than 2 per cent male cells). None of the freemartins consistently showed the presence of male cells in all organs cultured. The problem of the clinical diagnosis of freemartins is discussed in relation to these results.

Inherited renal cysts in pigs: results of breeding experiments.

A landrace boar with a previous history of siring progeny with cystic kidneys was bred to five unrelated large white sows. Thirty-eight of 61 progeny (62 per cent) were affected with renal cysts. This incidence does not differ significantly from that expected with autosomal dominant inheritance. Three of the dams and the boar were found at post mortem examination to have renal cysts. The number of cysts may be determined by polygenic inheritance. Study of the pathology of the cysts in one-day-old, 25- to 32-day-old and 370-day-old progeny indicated a complex pathogenesis including probable recruitment to the cyst population throughout the period studied. The syndrome studied did not resemble previously described polycystic syndromes of the pig nor was it closely comparable to any of the well described polycystic syndromes and renal cystic disorders of man.

A locomotor disorder clinically similar to spastic paresis in an adult Friesian bull.

A 5-year-old Friesian stud bull developed a progressive locomotor disorder on return to stud after a period of rest. He had defects in conformation exacerbated by poor condition. The hind limbs were excessively straight. When he stood or moved, the Achilles tendons and their associated muscles were rigid. The disorder clinically resembled spastic paresis of calves. Necropsy showed a degenerative arthropathy in all hind limb joints below the hip. Lesions were also in tendons and skeletal muscles. The M. flexor digitorum superficialis had severe type II cell atrophy with many ring, lobulated and moth-eaten type I cells.

Studies on a sheep freemartin.

A case of intersexuality in a Dorset horn ewe is described. Although possessing female external genitalia this animal had a male internal reproductive tract with inguinal testes, epididymes, vasa deferentia and seminal vesicles. No traces of cervix or uterus were present and the vagina was represented in its caudal part only. Chromosomal studies revealed chimaerism in peripheral leucocytes of the type 54, XX/54, XY, while other tissues revealed the normal female karyotype 54, XX. The ewe was born in a set of triplets with one dead male fetus and one living male. It was therefore concluded that the animal was a freemartin. The significance of this case and of the phenomenon of freemartisism in sheep is discussed.

Heifer sterility associated with single-birth freemartinism.

Thirty-four heifers not conceiving to three or more inseminations or natural service were bled and karyotyped by leucocyte culture. Twelve were found to be sex-chromosome chimeras of which five were single-born. Three out of the five singleton sex-chromosome chimeric heifers were slaughtered and at post mortem examination abnormalities of the reproductive tract were observed. Two the the slaughtered animals were Friesian heifers that had shown normal oestrous cycles and had reproductive organs apparently normal on clinical examination; however, one of them with 5 per cent male cells had a nonpatent cervix, while the other with 12 per cent male cells had non-patent uterine horns. Both heifers possessed functional ovaries, the former had an active corpus luteum and the latter had a developing follicle. The third heifer with 45 per cent male cells had a normal vagina, enlarged clitoris, seminal vesicles and gonads resembling fetal testes with both primitive ovarian and testicular structures. The Old Gloucester and Friesian heifers with 2-5 per cent and 12-0 per cent male cells are alive and have normal external genitalia but rudimentary uterine horns with no palpable gonads. Cytogenetic examination has demonstrated for the first time the existence of single-born freemartins resulting from the death of their male co-twins after fetal vascular anastomosis has been established.

The "barker" (neonatal respiratory distress) syndrome in the pig: its occurrence in the field.

A new syndrome, characterised by acute respiratory distress and by abnormalities of the skin, hair and thyroid, was the apparent cause of neonatal death in 35 (24 per cent) of 146 piglets sired by a large white boar in four small commercial pig units. The syndrome appears to be of genetic origin, inherited as an autosomal recessive trait. Its similarities with the respiratory distress syndrome (RDS) of the newborn infant and the "barker" syndrome of the newborn foal are discussed.