A survey of congenital defects of sheep

Occurrence of congenital disorders in Swiss sheep

BACKGROUND

The rates of congenital disorders in Swiss sheep were determined by a questionnaire which was sent to 3,183 members of the Swiss Sheep Breeders' Association.

FINDINGS

A total of 993 questionnaires were returned, giving a response rate of 31.2%. Of these, 862 questionnaires originated from farms keeping one of the predominant Swiss sheep breeds: Swiss White Alpine sheep, Brown-Headed Meat sheep, Swiss Black Brown Mountain sheep and Valais Blacknose sheep. During a 10-year-period, entropion was reported in 33.6% of the farms, brachygnathia inferior in 29.5%, abdominal/umbilical hernia in 15.9%, cryptorchidism in 10.5% and torticollis in 10.5%. The most significant difference between the four breeds (P<0.001) occurred for entropion in Swiss White Alpine sheep and Brown-Headed Meat sheep, brachygnathia inferior in Swiss Black Brown Mountain sheep, and scrotal/inguinal hernia in Valais Blacknose sheep. The Swiss White Alpine breed showed a significantly higher animal prevalence of entropion (6.2% in 2011 and 5.5% in 2012) than other breeds (P<0.001).

CONCLUSIONS

These findings indicate a breed-specific necessity for action, particularly regarding Swiss animal welfare legislation, especially entropion in Swiss White Alpine sheep is concerned. In general, careful selection of breeding stock is to be recommended.

An overview on congenital alopecia in domestic animals

Alopecia, that is, lack of hair in any quantity, is a frequent complaint of pet owners. Although mostly acquired, rare congenital forms of alopecia exist that are associated with abnormalities in hair follicle morphogenesis. Congenital alopecias can result in changes in quality or quantity of hair follicles and the hair fibres produced by them. They vary in terms of clinical presentation and mode of inheritance. Histopathology is usually needed in order to differentiate between a reduced number of otherwise normal hair follicles and qualitative hair follicle abnormalities. Although our understanding of the molecular mechanisms that drive hair follicle morphogenesis in mice and humans has significantly increased during the last decade, still very little is known about congenital alopecias in domestic animals. Because of their rarity and the general lack of knowledge about their pathophysiology, classification of congenital alopecias in domestic animals is still unsatisfactory. This article reviews hair follicle morphogenesis and its most important molecular mechanisms, and it discusses the various forms of congenital alopecia occurring in domestic animals that have been described in the literature, differentiating between hair follicle aplasia, hair follicle dysplasia (i.e. defects associated with hair follicle development and defects associated with hair shaft formation), and neuroectodermal dysplasias, the latter involving the hair follicle pigmentary system.

Clinical, cytogenetic and hormonal findings in a stallion with hypospadias--a case report

This case report describes a three-year-old Friesian stallion with hypospadias. Physical examination revealed a ventrocaudal deviation of the shaft of the penis and an incomplete glans penis. The urethral opening was 4 cm in length, slit-like and had a mucous membrane covering. A short fold ran from the ventral aspect of the anus and ended with a non-pigmented hairless area of skin. A human choriongonadotropin (hCG)-stimulation test resulted in an increase in the plasma levels of estrogen sulfate and testosterone, indistinguishable from that of a normal stallion. The karyogram had a normal number of chromosomes at 2n=64. The stallion was castrated, and histological evaluation of the testicular tissue was unremarkable. In contrast to other animal species and human beings, hypospadias is a rare congenital abnormality in stallions, the cause of which could not be elucidated in our patient.

Genetic alternatives to mulesing and tail docking in sheep: a review

A genetic solution to breech strike control is attractive, as it is potentially permanent, cumulative, would not involve increased use of chemicals and may ultimately reduce labour inputs. There appears to be significant opportunity to reduce the susceptibility of Merinos to breech strike by genetic means although it is unlikely that in the short term breeding alone will be able to confer the degree of protection provided by mulesing and tail docking. Breeding programmes that aim to replace surgical techniques of flystrike prevention could potentially: reduce breech wrinkle; increase the area of bare skin in the perineal area; reduce tail length and wool cover on and near the tail; increase shedding of breech wool; reduce susceptibility to internal parasites and diarrhoea; and increase immunological resistance to flystrike. The likely effectiveness of these approaches is reviewed and assessed here. Any breeding programme that seeks to replace surgical mulesing and tail docking will need to make sheep sufficiently resistant that the increased requirement for other strike management procedures remains within practically acceptable bounds and that levels of strike can be contained to ethically acceptable levels.

Hypospadias in a Himalayan cat

A one-year-old male Himalayan cat was presented with a history of chronic cystitis. Physical examination revealed that the cat had hypospadias. It was postulated that the abnormal urethral opening on the ventral aspect of the penis permitted faecal contamination of the preputial area and gave rise to the ascending infection. The hypospadias was surgically corrected and a complete recovery was achieved.

Congenital arthrogryposis: an inherited limb deformity in pedigree Suffolk lambs

Thirty of 52 pedigree Suffolk lambs (58 per cent) were born with arthrogryposis characterised by bilateral flexion rigidity of the metacarpophalangeal and carpal joints. The recent introduction of a breeding ram was identified as the only significant risk factor in the flock, and embryo transfer was used to test the hypothesis that the arthrogryposis was an inherited disorder associated with the introduction of this ram. Two adult ewes that had previously produced lambs with arthrogryposis by the ram and four of its affected daughters were available as donors, and 20 crossbred ewes were used as recipients. Ten Suffolk-crossed ewes that had no known familial relationship with the ram were also mated by the ram as controls and they produced 10 normal lambs. Following embryo transfer, 19 lambs were born, of which seven were stillborn; arthrogryposis was evident in 10 of the 12 live lambs. Analysis of the data suggested that in the population under study, arthrogryposis was inherited as an autosomal recessive condition.

The occurrence of schistosomus reflexus in bovine dystocia

The occurrence of schistosomus reflexus as a cause of bovine dystocia in south western Victoria is described. Examination of records made by 21 veterinarians during a 20-year period (1966 to 1985) showed that of 6901 cases of bovine dystocia attended, 90 (1.3%) were caused by schistosomus reflexus. Most cases (56.7%) were treated by embryotomy, 25.6% by caesarean section and 3.3% by simple traction. Treatment of the remaining 14.4% of cases was not completed and was considered hopeless, mainly because of the emphysematous condition of the foetus and the toxic condition of the cow, which gave a poor prognosis. Some of these hopeless cases were sent to slaughter, but most were euthanased by the attending veterinarian. Sixty-nine (76.7%) of the patients were cows and 21 (23.3%) were heifers. Seventy-two (80%) were dairy breeds and 18 (20%) were beef breeds. Jersey was the main dairy breed (63.8%) and Hereford the dominant beef breed.

Congenital defects of sheep

With increasing incrimination of viruses, plants, and drugs as causes of ovine congenital defects, concerted efforts are required to identify environmental teratogens. Expanding knowledge of congenital defects requires studying as many defective lambs as possible; recording and documenting; detailed diagnostic examinations; genetic analyses and chromosomal examinations, whenever possible; and field investigations. Adopting standardized classification, terminology, and diagnostic procedures should improve descriptions, diagnoses, and interdisciplinary exchange of information. That, in turn, should improve our knowledge of and diagnosis of congenital defects of sheep in the future. Finally, veterinary clinicians and diagnosticians are encouraged to take an interest in congenital defects and teratology.

Genetic diseases of sheep and goats

Congenital malformations and inherited disorders constitute a substantial proportion of the afflictions seen in sheep and goats. Of these, malformations tend to be similar in both species, whereas the genetic diseases encountered to date, with the exception of a few, are different. Of the 28 genetic diseases of sheep and goats described in this review, 60% and 62.5%, respectively, are monogenic disorders. For a majority of the monogenic recessive disorders encountered in these species, the carrier state is not detectable at present, whereas in others, in which a biochemical lesion is known (dermatosparaxis, erythrocyte glutathione deficiency, globoid cell leukodystrophy and glycogen storage disease), the carrier state is detectable with the aid of enzyme and surface protein markers. The latter group and the dominant disorders (anury, cataract, glomerulonephritis, and lethal grey in sheep; gynecomastia and anotia-microtia complex in goats) are easy to eliminate through selective breeding. The polygenic disorders (entropion, epidermolysis bullosa, hereditary chondrodysplasia, and muscular dystrophy of sheep, and udder problems in goats) are more difficult to eradicate, because the mutant genes responsible for these traits generally do not declare themselves until inbreeding brings together a critical concentration to create a health crisis in some, whereas others, which are only short of a few of these mutant genes, might go totally unaffected and therefore undetected. Chromosome defects of the structural nature (translocations) seen in sheep and goats generally create meiotic disturbances, which in a majority of cases lead to subfertility, whereas sex chromosome aneuploids are generally sterile.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital ocular defects in food-producing animals

Congenital ocular defects in neonates pose a diagnostic challenge to veterinarians. Defects are usually obvious at birth, but detection depends on the nature and extent of the defect. In addition to congenital ocular defects, other abnormalities may be manifest including multiple system involvement with embryonic mortality, fetal death, mummification, abortion, dysmaturity, premature birth, full-term stillbirth, or nonviable or viable neonate. Many defective neonates are not reported or escape monitoring systems. Although congenital ocular defects are rare, they are important and should be diagnosed. All congenital defects should be regarded as genetic until proven otherwise. Many ocular defects are inherited as simple autosomal recessive traits. Polygenic inheritance appears to be of increasing importance.

Concepts of multiple congenital contractures (arthrogryposis) in man and animals

This is a concept of multiple congenital contractures, based upon clinical experience with the malformation and available literature, leading to a conception of the multiple categories of etiology, which cause neuropathic or myopathic muscle weakness or limb immobilization. The muscle weakness and imbalance of muscle power around the joints elicits a physiological compensatory collagenic response, which replaces atrophied muscle fibers with connective tissue and thickens the joint capsule sufficiently to result in prenatal fixation of limb segments at the joint.

Frequency of congenital abnormalities and of anatomical variations among JAX rabbits

The frequency of congenital abnormalities and anatomical variations as observed among JAX rabbits is reported. Data were drawn from 32,082 inbred and partially inbred rabbits and 3,208 hybrids from the colony of the Jackson Laboratory over an eight-year period. Data reported here include stillbirths, rabbits dying from natural causes, and those killed for specific experimental regimens. Frequency data are based on the number of abnormalities observed in each category as a function of the total number of animals necropsied. This is approximately 95% of the animals born during the eight-year period and gives the frequency of abnormalities within each category rather than the number of individuals with one or more abnormalities. Anatomical variations have been found in almost all organ systems of JAX rabbits. Their presence adds to our knowledge of the characteristics of these strains, a knowledge that is critical to the understanding of the results of experimental manipulation or for determination of the presence of new mutations. There is considerable between-strain variation. Where frequencies are relatively high, the conditions are either known or suspected to be of genetic origin. Most of the anomalies are not deleterious, or their frequency is so low as to cause no problems within the colony. Hybrid populations have substantially fewer anomalies than do the parental strains. Where frequency is relatively high, it tends to be intermediate between the parental strains.