Morphological Variation of “Complex Vertebral Malformation” in Holstein Calves

A study was performed to investigate the morphological expression of the inherited syndrome “complex vertebral malformation” (CVM) in Holstein calves. A total of 107 late-term aborted, premature, or neonatal calves suspected of having CVM were necropsied and retrospectively analyzed for the causal mutation in the gene SLC35A3. Sixty-two calves were homozygous affected, 16 were heterozygous, and 29 were homozygous normal. Calves affected by CVM were growth retarded. Vertebral lesions identified by radiography were present in 61 cases, of which 58 also had costal malformation. Malformation of the head, primarily in the form of dysplasia or palatoschisis, was present in 15 cases. Bilateral symmetric flexion of the carpal and metacarpophalangeal joints was present in all cases, whereas posterior arthrogryposis was found in 54 cases. Interventricular septal defects occurred in 33 calves, often in combination with other cardiac malformations. A wide spectrum of additional malformations was found. Other congenital syndromes were in most cases distinguishable from CVM on a morphological basis. However, a calf with a prenatal infection with bovine virus diarrhea virus constituted a phenocopy. The study demonstrated that the morphological expression of CVM is wide, but certain aspects, i.e., growth retardation, vertebral malformation, and symmetric arthrogryposis, are almost constant findings. However, cases without vertebral defects and phenocopies constitute a diagnostic problem. A presumptive diagnosis of CVM can in most cases be based on necropsy findings combined with information on descent and paternal CVM genotype, whereas a definitive diagnosis requires genotyping.

Genome-wide next-generation DNA and RNA sequencing reveals a mutation that perturbs splicing of the phosphatidylinositol glycan anchor biosynthesis class H gene (PIGH) and causes arthrogryposis in Belgian Blue cattle

BACKGROUND

Cattle populations are characterized by regular outburst of genetic defects as a result of the extensive use of elite sires. The causative genes and mutations can nowadays be rapidly identified by means of genome-wide association studies combined with next generation DNA sequencing, provided that the causative mutations are conventional loss-of-function variants. We show in this work how the combined use of next generation DNA and RNA sequencing allows for the rapid identification of otherwise difficult to identify splice-site variants.

RESULTS

We report the use of haplotype-based association mapping to identify a locus on bovine chromosome 10 that underlies autosomal recessive arthrogryposis in Belgian Blue Cattle. We identify 31 candidate mutations by resequencing the genome of four cases and 15 controls at ~10-fold depth. By analyzing RNA-Seq data from a carrier fetus, we observe skipping of the second exon of the PIGH gene, which we confirm by RT-PCR to be fully penetrant in tissues from affected calves. We identify - amongst the 31 candidate variants - a C-to-G transversion in the first intron of the PIGH gene (c211-10C > G) that is predicted to affect its acceptor splice-site. The resulting PIGH protein is likely to be non-functional as it lacks essential domains, and hence to cause arthrogryposis.

CONCLUSIONS

This work illustrates how the growing arsenal of genome exploration tools continues to accelerate the identification of an even broader range of disease causing mutations, therefore improving the management and control of genetic defects in livestock.

[Pathologic-anatomical changes in newborn goats caused by an intrauterine Schmallenberg virus infection]

A complex of various malformations in newborns was observed to an increased extent in sheep farms in the 2011/2012 lambing season. An intrauterine Schmallenberg virus (SBV) infection was identified as the cause of these malformations. To date, a detailed pathological description of the deformity complex has only been given for bovine and ovine newborns.The aim of this study was therefore to provide a description of pathologic-anatomical congenital malformations in goat kids caused by intrauterine SBV infection. To this end, pathologic-anatomical and molecular biological investigations by PCR were carried out on 37 goat kids and 457 lambs from 238 sheep and goat farms in order to carry out an interspecies comparison. Of the 37 goat kids dissected, it was possible to identify a SBV infection in twelve animals (32.4%) by RT-PCR. In nine animals (24.3%) displaying pathological-anatomical malformations SBV could not be detected by PCR. The following malformations were observed: athrogryposis, deformation of spinal column, torticollis, asymmetry of the skull, brachygnathia inferior, cerebellar hypoplasia, cerebellar aplasia and internal hydrocephalus. Arthogryposis was the most common malformation, both in animals with positive PCR results and those with negative PCR results. This study documents congenital malformations caused by an intrauterine SBV infection for the first time on a large number of newborn goats.

[Congenital malformation of the front limbs in a llama (Lama glama): polydactyly in combination with arthrogryposis]

A male, 10 month old llama with malformation of both front limbs was presented. Both front limbs had one more digit located medially. The distal phalanx of this additional digit at the left front limb reached the ground by the tip of the keratinzed pad and the toenail. The accessory digit at the right front limb was bent in a 90 degree angle caudolateraly. Beside the digital bones of the accessory digits the second metacarpal bone and the first carpal bone could be detected in both front limbs by radiological examination. Secondary a bilateral slight carpal valgus deformity could be seen.

A pedigree-analysis approach to the descriptive epidemiology of autosomal-recessive disorders

We describe a pedigree-analysis approach to estimating descriptive epidemiological parameters for autosomal-recessive disorders when the ancestral source of the disorder is known. We show that the expected frequency of carriers in a cohort equals the gene contribution of the ancestral source to that cohort, which is equivalent to the direct (additive) genetic relationship of that ancestor to the cohort. Also, the expected incidence of affected foetuses ranges from (1/2)F* to F*, where F* is the mean partial inbreeding coefficient (due to the ancestor) of the cohort. We applied this approach to complex vertebral malformation (CVM) in Holstein-Friesians in Australia, for which the ancestral source is a USA-born bull, Carlin-M Ivanhoe Bell. The estimated frequency of carriers was 2.47% for the 1992-born and 4.44% for the 1997-born cohort of Holstein-Friesian cows in Australia. The estimated incidence of affected foetuses/calves was considerably less than one per thousand, ranging from 0.0024 to 0.0048% for the 1992-born cohort, and from 0.0288 to 0.0576% for the 1997-born cohort. These incidences correspond to expected numbers of affected female foetuses/calves ranging from 2 to 4 for the 1992-born cohort and from 28 to 56 for the 1997-born cohort. This approach is easy to implement using software that is readily available.

Linkage mapping of the locus for inherited ovine arthrogryposis (IOA) to sheep chromosome 5

Arthrogryposis is a congenital malformation affecting the limbs of newborn animals and infants. Previous work has demonstrated that inherited ovine arthrogryposis (IOA) has an autosomal recessive mode of inheritance. Two affected homozygous recessive (art/art) Suffolk rams were used as founders for a backcross pedigree of half-sib families segregating the IOA trait. A genome scan was performed using 187 microsatellite genetic markers and all backcross animals were phenotyped at birth for the presence and severity of arthrogryposis. Pairwise LOD scores of 1.86, 1.35, and 1.32 were detected for three microsatellites, BM741, JAZ, and RM006, that are located on sheep Chr 5 (OAR5). Additional markers in the region were identified from the genetic linkage map of BTA7 and by in silico analyses of the draft bovine genome sequence, three of which were informative. Interval mapping of all autosomes produced an F value of 21.97 (p < 0.01) for a causative locus in the region of OAR5 previously flagged by pairwise linkage analysis. Inspection of the orthologous region of HSA5 highlighted a previously fine-mapped locus for human arthrogryposis multiplex congenita neurogenic type (AMCN). A survey of the HSA5 genome sequence identified plausible candidate genes for both IOA and human AMCN.

Partial tarsal arthrodesis and botulinum toxin A injection for correction of tarsal arthrogryposis in a cat

An 11-week-old, domestic shorthair cat was presented for evaluation of a congenital right tarsal deformity. The cat was non-weightbearing lame on the right hindlimb. There was severe tarsal hyperextension and concurrent spasticity/contracture/shortening of the gastrocnemius muscle-tendon. The cat was otherwise healthy. Radiographically there was luxation of the proximal intertarsal joint and talocrural hyperextension. Treatment with 10 mu/kg botulinum toxin A (Botox; Allergan) intramuscular injections directly into the gastrocnemius muscle and passive physiotherapy marginally improved the range of motion in the talocrural joint. Definitive surgical treatment with partial tarsal arthodesis produced an excellent clinical outcome. This case report demonstrates the successful treatment of a severe congenital tarsal abnormality and also documents the first clinical use of botulinum toxin in a feline patient.

Radiation hybrid mapping of 18 positional and physiological candidate genes for arthrogryposis multiplex congenita on porcine chromosome 5

We report the chromosomal assignment of 18 porcine genes to human homologues using the INRA-Minnesota swine radiation hybrid panel (IMpRH). These genes (CACNA1C, COL2A1, CPNE8, C3F, C12ORF4, DDX11, GDF11, HOXC8, KCNA1, MDS028, TMEM106C, NR4A1, PHB2, PRICKLE1, Q6ZUQ4, SCN8A, TUBA8 and USP18) are located on porcine chromosome 5 (SSC5) and represent positional and functional candidates for arthrogryposis multiplex congenita (AMC), which maps to SSC5. CPNE8, PRICKLE1, Q6ZUQ4 and TUBA8 were mapped to the interval for pig AMC between microsatellites SW152 and SW904. Three SNPs in TUBA8 co-segregated with the AMC phenotype in 230 pigs of our research population without recombination and could be used as a genetic marker test for AMC. In addition, we provide evidence that a small chromosomal region of HSA22q11.2 evolutionarily corresponds to SSC5q12-q22 (and contains the human homologues of porcine SW152, Q6ZUQ4, TUBA8 and USP18), while the regions flanking HSA22q11.2 on SSC5 correspond to HSA12p13 and HSA12q12. We identified seven distinct chromosomal blocks, further supporting extensive rearrangements between genes on HSA12 and HSA22 in the AMC region on SSC5.

Radiation hybrid mapping of genes and newly identified microsatellites in candidate regions for bovine arthrogryposis-palatoschisis and progressive ataxia based on comparative data from man, mouse and rat

A comparative pathology and mapping strategy was used to initiate a study on two bovine genetic diseases: arthrogryposis-palatoschisis and progressive ataxia, which affect mainly Charolais cattle. Bibliographic studies provided information on the pathology of these diseases, which helped to define similar diseases in other species. Animals affected by bovine arthrogryposis-palatoschisis display similar symptoms to those of muscular dysgenesis, mouse mutants and animals with progressive ataxia to those of Long Evans Shaker rat mutants. Candidate regions are respectively human chromosome 1q32 (BTA16) containing the gene CACNA1S and human chromosome 18q23 (BTA24) containing the gene myelin basic protein (MBP). Primer pairs were designed for 15 loci around each candidate gene, in a region of about 20 megabases and were used to screen a bovine Bacterial Artificial Chromosome (BAC) library. Eighteen microsatellites were found in the identified BAC clones, 11 on BTA24 and seven on BTA16. The genes and microsatellites were mapped by radiation hybrid (RH) analysis and a RH map was obtained for each region with 18 new localizations on BTA16 and 23 on BTA24. Comparative human-bovine analysis of the MBP region shows a good conservation of gene order while that of the CACNA1S region shows several breakpoints.

Evaluation of the inheritance of the complex vertebral malformation syndrome by breeding studies

To investigate the congenital complex vertebral malformation syndrome (CVM) in Holstein calves, two breeding studies were performed including 262 and 363 cows, respectively. Cows were selected from the Danish Cattle Database based on pedigree and insemination records. Selected cows were progeny of sires with an established heterozygous CVM genotype and pregnant after insemination with semen from another sire with heterozygous CVM genotype. Following calving the breeders should state, if the calf was normal and was requested to submit dead calves for necropsy. In both studies, significantly fewer CVM affected calves than expected were obtained; a finding probably reflecting extensive intrauterine mortality in CVM affected foetuses. The findings illustrate increased intrauterine mortality as a major potential bias in observational studies of inherited disorders.

Comparison of plasma disposition of alkaloids after lupine challenge in cattle that had given birth to calves with lupine-induced arthrogryposis or clinically normal calves

OBJECTIVE

To compare plasma disposition of alkaloids after lupine challenge in cattle that had given birth to calves with lupine-induced arthrogryposis and cattle that had given birth to clinically normal calves and determine whether the difference in outcome was associated with differences in plasma disposition of anagyrine.

ANIMALS

6 cows that had given birth to calves with arthrogryposis and 6 cows that had given birth to clinically normal calves after being similarly exposed to lupine during pregnancy.

PROCEDURES

Dried lupine (2 g/kg) was administered via gavage. Blood samples were collected before and at various time points for 48 hours after lupine administration. Anagyrine, 5,6-dehydrolupanine, and lupanine concentrations in plasma were measured by use of gas chromatography. Plasma alkaloid concentration versus time curves were generated for each alkaloid, and pharmacokinetic parameters were determined for each cow.

RESULTS

No significant differences in area under the plasma concentration versus time curve, maximum plasma concentration, time to reach maximum plasma concentration, and mean residence time for the 3 alkaloids were found between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Because no differences were found in plasma disposition of anagyrine following lupine challenge between cattle that had given birth to calves with arthrogryposis and those that had not, our findings do not support the hypothesis that between-cow differences in plasma disposition of anagyrine account for within-herd differences in risk for lupine-induced arthrogryposis.

Arthrogryposis, hydranencephaly and cerebellar hypoplasia syndrome in neonatal calves resulting from intrauterine infection with Aino virus

To determine the teratogenic potential of Aino virus (AINOV) in cattle, pregnant cows and fetal cattle were infected with a fresh isolate of AINOV. Five pregnant cows were inoculated intravenously with the virus at 122 to 162 days of gestation and allowed to give birth. All of the cows developed neutralizing antibodies to the virus, indicating that the cows had been infected with the virus; however, no clinical abnormalities were seen in their six newborn calves, and no specific antibodies to the virus were detected in the precolostral serum of calves. Five fetuses with fetal ages ranging from 132 to 156 days were inoculated in utero with the virus. One weak newborn and four stillborn calves were delivered at gestation days 256 to 263, i.e., less than the standard gestation term; they had congenital abnormalities including arthrogryposis, hydranencephaly and cerebellar hypoplasia. Antibodies specific to AINOV were detected in their precolostral serum. These results demonstrate that AINOV is a potential etiological agent of congenital malformation of cattle.

[Arthrogryposis associated with facial scoliosis and torticollis in German Holstein calves]

In 13 German Holstein calves from two different dairy farms arthrogryposis of the front legs, facial scoliosis and torticollis were observed. Obvious environmental reasons could not be found. Chromosomal anomalies in two affected calves were not detectable. A striking feature was the high frequency of affected calves among the offspring of one natural service sire. A plausible explanation of the congenital anomalies observed is a dominantly inherited mutation restricted to germ cells.

Survival motor neuron (SMN) polymorphism in relation to congenital arthrogryposis in two Piedmont calves (piemontese)

The term arthrogryposis refers to a symptom complex that is characterised by congenital limb contractures. Arthrogryposis has been reported in man, in farm animals and in pets. Several forms have been reported to have a genetic origin in man. In Brown Swiss and Holstein Friesian cattle, congenital contractures have been recorded and classified as spinal muscular atrophy (SMA). The survival motor neuron gene (SMN) has been suggested as a candidate gene for SMA. In the last 20 years, the National Association of Piedmont Cattle have recorded arthrogryposis cases. We cloned and sequenced SMN cDNA extracted from the spinal cord samples of two animals: one Piedmont calf showing a severe clinical form of arthrogryposis and one normal Piedmont calf. In the affected calf, more than 50% of the 5' end clones showed a ATG > TTG single nucleotide polymorphism (SNP) in exon 1 that should determine a Met > Leu aminoacid change (single point mutation M3L). This mutation is associated with a 9 bp increase length of 5' UTR and to a TTC-->TTT silent mutation in exon 1. No single point mutation or 5' end polymorphism was shown in healthy animals and in the remaining 50% of the clones from the affected calf. We hypothesise a possible pathogenic effect of the 5' end-exon 1 polymorphism.

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.

Perosomus elumbis (vertebral agenesis and arthrogryposis) in a stillborn Holstein calf

Perosomus elumbis, an infrequently encountered congenital anomaly of unknown etiology, was studied in a female Holstein calf. This error of morphogenesis represents a set of multiorgan malformations that produce a deformity of the caudal one third of the fetus. In this case, the spinal and pelvic malformations were radiographed and then dissected. Intra-abdominal abnormalities of the soft tissues are also described. The normal sequential embryologic development of the vertebrate skeleton, anterior-posterior fetal positioning, and neural tube migration are discussed. An extensive literature of this birth defect in cattle (and sheep) is reveiwed. The reports from a period covering 165 years are compared with the pathologic features in this case. Chromosomal aberrations within the homeobox gene family are postulated to be contributory factors in the development of this type of dysorganogenesis.

Teratogenic and fetotoxic effects of two piperidine alkaloid-containing lupines (L. formosus and L. arbustus) in cows

Cleft palate and minor front limb contractures were induced in calves by maternal ingestion of the piperidine alkaloid-containing lupines, Lupinus formosus and L. arbustus. Crooked calf disease, which includes an occasional cleft palate, is a congenital condition of widespread occurrence in cattle in the western U.S. and Canada. It is known to occur after maternal ingestion of certain species of Lupinus during specific gestational periods. Although many lupine species contain quinolizidine alkaloids including the teratogenic alkaloid anagyrine, L. formosus and L. arbustus produce piperidine alkaloids including the reported teratogen ammodendrine. In addition to ammodendrine, L. formosus contains both N-acetyl hystrine and N-methyl ammodendrine, whereas L. arbustus contains ammodendrine, trace amounts of N-methyl ammodendrine, and no N-acetyl hystrine. L. formosus and L. arbustus were fed to pregnant cows at equivalent ammodendrine doses during a 10-day period from days 40-50 of gestation. One calf from a cow fed L. formosus had a full cleft palate. Embryonic death and resorption of one fetus and minor front limb contractures (arthrogryposis) in another calf occurred with two cows fed L. arbustus. Alkaloid analysis of blood samples taken during the feeding period, and up to and including 48 hours after the last dose, demonstrated comparative plasma elimination times with N-methyl ammodendrine > ammodendrine > N-acetyl hystrine. The objectives of this experiment were to: 1) determine if N-acetyl hystrine is a potential teratogen; and 2) define the narrow cleft palate induction period in cows.

Teratogenicity of Aino virus in the chick embryo

Aino virus (JaNAr 28 strain), a possible agent of a congenital anomaly of calves, was inoculated into the yolk sac of chick embryos at a dose of 10(2), 10(3), 10(4) or 10(5) TCID50 0.2 ml-1 at four, six or eight days of incubation. At 21 days of incubation all the unhatched embryos or hatched chickens in the experimental and control groups were sacrificed for pathological examination. The incidence of hydranencephaly, cerebellar hypoplasia or agenesis and arthrogryposis or scoliosis was highest (85 per cent in the chicks inoculated with 10(3) TCID50 0.2 ml-1 at eight days of incubation. The lesions were very similar to those found in congenital abnormalities in calves suspected of a natural infection with Aino virus.

Ovine fetal malformations induced by in utero inoculation with Main Drain, San Angelo, and LaCrosse viruses

The teratogenic potential of three bunyaviruses, two California serogroup bunyaviruses, LaCrosse virus and San Angelo virus, and a Bunyamwera serogroup member, Main Drain virus, in sheep was studied following in utero inoculation of ewes in early gestation. Although Main Drain virus appeared to be most teratogenic, all three viruses induced a range of lesions including arthrogryposis, hydrocephalus, fetal death, axial skeletal deviations, anasarca, and oligohydramnios. The teratogenic effects of these viruses are identical to those described in ovine infections by Cache Valley and Akabane viruses. Demonstration of a common bunyaviral tropism for fetal tissue infection that results in congenital brain and musculoskeletal malformations provides evidence that human in utero infection by bunyaviruses could result in similar malformations in human infants.

Hydranencephaly, cerebellar hypoplasia, and myopathy in chick embryos infected with aino virus

Pathogenesis of Aino virus (AIV), a suspected causative agent of congenital abnormalities of calves, has not yet been established by experimental infection of dams. To investigate the pathogenesis, 10(3) median tissue culture infective doses per 0.2 ml of AIV strain JaNAr 28 was inoculated into the yolk sac of 8-day-old chick embryos. At 4, 7, 10, and 13 days post-inoculation (PI) 20 eggs were opened and macro- and microscopic studies combined with virus recovery and immunohistochemical detection of the virus antigen were performed. At 7 to 13 days PI chick embryos manifested marked hydranencephaly, cerebellar hypoplasia, arthrogryposis, and scoliosis, with the highest incidences of 86.7%, 73.3%, 80.0%, and 20.0%, respectively. At 4 days PI the viral antigen was found in nerve cells, gitter cells in mild necrotic foci of the central nervous system (CNS), degenerative myotubules, and macrophages in the interstitium, which was associated with the early phase of AIV-induced encephalitis and polymyositis, with occasional accompanying hemorrhage and clumping of myotubular fragments. From 7 to 10 days PI, AIV antigen increased markedly in the liquefactive necrosis and in both degenerative and normal-looking myotubules in conjunction with developing hydranencephaly and arthrogryposis. The encephalitis and myositis had a tendency to mitigate by 10 days PI, coincident with a slight decrease in amount of AIV antigen. At 13 days PI there was almost no detectable AIV antigen in CNS and skeletal muscles, probably due to depletion of cells having affinity to AIV.

Congenital defects of the bovine musculoskeletal system and joints

A variety of structural and functional congenital defects affecting the central nervous system of cattle have been identified. This article discusses specific defects of the central nervous system. Spastic and paralytic, metabolic, and storage diseases are reviewed.

An outbreak of Akabane virus-induced abnormalities in calves after agistment in an endemic region

During 1988, 2 farmers in the Bega district agisted pregnant cattle in the Hunter Valley of New South Wales. On return to the district to calve, 54% of calves from herd 1 and 30% of calves from herd 2 were affected with congenital arthrogryposis or hydranencephaly caused by Akabane virus infection. Field observations and laboratory findings from this outbreak are presented, illustrating the danger of moving immunologically naive animals into areas where Akabane virus is endemic.

Searching for genetic markers for hereditary diseases in cattle by means of DNA fingerprinting

Losses caused by inherited diseases affect not only the breeder's income but also the breeding programs themselves. In Switzerland the cardiomyopathy of cattle and the syndrome of arachnomelia and arthrogryposis are currently being investigated in order to find genetic markers for these diseases. It seems that DNA fingerprinting with multilocus probes is the most efficient approach available at present. Microsatellites analyzed with the polymerase chain reaction technique will provide a usable marker map within the next ten years and will therefore provide a perfect tool to find markers for hereditary diseases.

[The occurrence of hereditary congenital arthromyodysplasia (arthromyodysplasia congenita hereditaria) in calves of the Hessian cattle population]

The Arthromyodysplasia congenita hereditaria is marked by the flexion and fixation of the front leg joints. The statistic analysis of all available data from 536 calves showed that male calves and twins are significantly more affected. The course, duration and delivery date in the pregnancy of cows with arthromyodysplastic calves showed no peculiarity. Concomitant defects of arthromyodysplasia of the forelimbs were spine- and heart defects and neuromyodysplasia of the hind legs. Three bulls KUR, KER and ALD were ancestors of 37% of all registered calves. This frequency of arthromyodysplasia in the bloodline of these three bulls seem to be a sign for a genetic factor with a strong penetrance in male calves.

Evidence that Cache Valley virus induces congenital malformations in sheep

An outbreak of congenital abnormalities occurred in sheep at San Angelo, Texas, between December 1986 and February 1987. Of 360 lambs born, 19.2% had arthrogryposis or other musculo-skeletal problems and hydranencephaly (AGH), and the total neonatal loss was 25.6%. In 1987, all ewes that were tested with AGH lambs had antibody to Cache Valley virus (CVV), whereas 62% of the ewes with normal lambs had CVV-specific antibody. Pre-colostral serum samples from AGH lambs had neutralizing antibody to CVV. An increase in prevalence of CVV-specific antibody, from 5% during the spring of 1986 to 63.4% during the winter of 1987, occurred during a time that included the gestation of these affected lambs, as well as a period of increased rainfall. The isolation of a CVV-related strain from a sentinel sheep in October 1987 confirmed the continued presence of this virus in the pasture where this outbreak occurred and provided a recent field strain for future studies.

Laboratory investigation of a naturally occurring outbreak of arthrogryposis-hydranencephaly in Texas sheep

An epizootic of abortions, weak lambs, stillbirths, and congenital arthrogryposis-hydranencephaly occurred in a sheep flock in West Texas. The outbreak began during the first week of January 1987 and continued through the third week of February 1987. Lambs born after February 1987 were not affected. A high incidence of antibodies to Cache Valley virus (Texas 7856 isolate) was demonstrated in the ewes' serum and in precolostral serum from affected lambs. No virus was isolated from tissues and body fluids of the affected lambs. The clinical, pathological, and immunological features of the epizootic were similar to those reported in Akabane virus infection in sheep. Although serological findings strongly suggest Cache Valley virus as the etiological agent of this outbreak, transmission studies are needed.

Ovine arthrogryposis and central nervous system malformations associated with in utero Cache Valley virus infection: spontaneous disease

Gross appearance and histologic lesions seen in 15 newborn lambs in an outbreak of congenital arthrogryposis with hydrocephalus or hydranencephaly (CAH) in Texas are described. Severe arthrogryposis with skeletal muscle hypoplasia was seen in limbs of affected lambs. Spinal column deformities were also present. Multiple central nervous system (CNS) malformations were present in CAH lambs including micrencephaly, cerebellar hypoplasia, micromelia, hydrocephalus, hydranencephaly, and porencephaly. Histologic lesions consisted primarily of areas of necrosis and loss of the paraventricular neuropil and motor neurons in the CNS and a resolving myositis with poorly developed myotubular myocytes in skeletal muscle. Seroepidemiologic studies on the flock and serologic data from heart blood taken from the stillborn affected lambs indicated that the outbreak was due to in utero infection with Cache Valley Virus.

The development of Akabane virus-induced congenital abnormalities in cattle

A prospective study of the incidence and severity of congenital deformities of calves, attributable to maternal infection by Akabane virus, was carried out on a population of 174 susceptible animals that were between one and nine months pregnant at the time of infection. The study was carried out in the Hunter Valley of New South Wales during 1983, after an epidemic of Akabane virus infection in late February to early March 1983. The incidence of virus-induced abnormalities in calves and fetuses was 17.8 per cent (31/174). The highest incidence of abnormalities occurred during the third and sixth months of gestation (27 to 29 per cent). The earliest abnormality was observed after infection at 76 days of gestation, and the last after infection at 249 days. The development of the pathological entities of hydranencephaly/porencephaly and arthrogryposis were found to be quite distinct. Cases of hydranencephaly and porencephaly developed after infection between 76 and 104 days of gestation whereas arthrogryposis developed after infection between 103 and 174 days of infection. It was concluded that the type of congenital deformity produced by maternal infection with Akabane virus was dependent on the stage of fetal development at the time of infection. The data suggest that the infection was transplacental and that fetuses of less than two months of age were protected from infection.

Congenital hydranencephaly and arthrogryposis of Corriedale sheep

A syndrome of congenital malformations in Corriedale sheep characterised by brachygnathia inferior, campylognathia, tetraemlic arthrogryposis, kyphoscoliosis, hydranencephaly and hypoplasia of the brain stem, cerebellum and spinal cord occurring in various combinations is described. Histologically there was generalised hypomyelinogenesis and hypoplasia of the central nervous system with neurogenic atrophy of skeletal muscle. The syndrome resembled that caused by congenital infection with Akabane virus, however, serological, pathological and epidemiological data indicated that Akabane virus was not involved. The results of a breeding trial suggested that the disorder may be transmitted with an autosomal recessive mode of inheritance.

Decreased number of alpha-motoneurons in the cervical intumescence of calves with arthrogryposis multiplex congenita of both thoracic limbs

The number of alpha-motoneurons in the spinal cord segments C6 to Th2 of five calves with Arthrogryposis Multiplex Congenita (AMC) and of five normal calves was compared. A statistically highly significant reduction in the number of alpha-motoneurons in segment C6 was observed in the affected calves. Two hypotheses to explain the effect of these findings were proposed. Firstly, it was thought that AMC may result from paresis of some muscles of the girdle, shoulder and elbow. Secondly, it was postulated that the decrease in the number of alpha-motoneurons in C6 may have induced a radial nerve dysfunction resulting in AMC.

Crooked calf disease: a histological and histochemical examination of eight affected calves

Macroscopic, histopathologic, and histochemical investigations were made on a group of eight neonatal Angus X Hereford calves, selected from an ongoing outbreak of crooked calf disease among calving heifers. Arthrogryposis of the forelimbs was seen to varying degrees in all eight animals, and torticollis was present in six calves. Histopathology, using hematoxylin and eosin stain, did not reveal any striking or consistent lesion in the affected animals; the majority of the tissues sampled were normal. Muscle samples were processed for adenosine triphosphatase (ATPase) and NADH-tetrazolium reductase (NADH-tr) histochemistry, and the data suggest that a primary myopathy is not responsible for the congenital anomalies in the affected calves.

[Congenital flexure of the forelimbs in calves]

The incidence of congenital multiple arthrogryposis in newborn calves during the period from September 1982 to September 1983 was studied by conducting a questionnaire on 2,204 dairy farms in the province of Overijssel. This entity was observed on 19 per cent of the farms with Meuse-Rhine-IJssel breed and on 12 per cent of those with the Friesian-Dutch or Friesian-Dutch/Dutch-Friesian breed of cattle. Bull-calves showing normal or heavy birth weights following a normal period of gestation were mainly affected. There was a considerable difference in incidence between sires.

Multiple congenital malformations of the face, nervous system and musculoskeletal system of pigs

Multiple congenital malformations occurred in 21 of 26 pigs (81%) in 3 litters from 2 piggeries. Two of 26 pigs (7%) were mummified while 3 of 26 (11%) were normal. Cheiloschisis was seen in all malformed pigs and was accompanied by various combinations of palatoschisis, arhinencephaly, hypoplasia of the spinal cord, arthrogryposis of the pelvic limbs, polydactyly, renal lesions and cauliflower ears. Histological examination suggested that arthrogryposis was due to neurogenic muscular atrophy. The teratogen was not identified.

Neurologic diseases

The responses of apparently healthy newborn foals to neurologic testing differ significantly from those of adult horses. These responses and the diagnostic techniques pertinent to neurologic problems are reviewed as a basis for evaluation of the compromised neonatal foal. The more frequently encountered neurologic diseases are discussed in a problem-oriented format. These clinical problems include behavioral abnormalities, convulsions, changes in consciousness, blindness, ataxia without loss of strength, ataxia with weakness and paralysis, and the floppy foal.

High incidence of abortions and congenital deformities of unknown aetiology in a beef herd

In 1980, 16 abortions or stillbirths occurred and 26 deformed calves were born in a beef herd of 115 Friesian cross Hereford cows mated to Charolais bulls. The deformities were principally arthrogryposes with contractures, particularly of the forelimbs, and various skull abnormalities. Following investigation it was considered highly unlikely that hereditary causes, infectious agents or a nutritional deficiency were responsible. The most likely cause was exposure to an unidentified teratogen early in pregnancy.

Variability in limb malformations and possible significance in the pathogenesis of an inherited congenital neuromuscular disease of Charolais cattle (syndrome of arthrogryposis and palatoschisis)

Limb abnormalities in 30 calves with an inherited congenital neuromuscular disorder known as syndrome of arthrogryposis and palatoschisis were classified according to the range of severity of joint deformity in either flexion or extension, and restricted joint movement. Joint movement was variably affected; it was either normal, lax, restricted in the range of mobility, or occasionally, fixed. The characteristic findings were: bilateral hyperextension of the hind fetlock, flexion deformity of the forelimb that particularly involved the fetlock and the carpus, with restricted articular movement and complete rigidity in some cases. One-third of calves also had medial deviation of the forelimb due to angular deformity of articular surfaces in the carpus. All nine live calves were floppy due to marked generalized muscular hypotonia. Birth weight of deformed calves was reduced. In some calves muscle development was impaired as judged by muscle weight, and histological examination. In some calves the gross appearance, muscle weight and histological examination revealed no abnormal development and indicated that the effects on skeletal muscle were secondary. No lesions were found in the spinal cord of 23 of 24 calves examined histologically. The remaining calf had a localized cavitation in the dorsal white matter at T2-3. Based on the observations in calves in this study it is proposed that both primary and secondary factors contribute to the phenotypic expression of this congenital deformity. The primary lesion is considered to be a neurogenic abnormality of differentiation in the central nervous system. Cytogenetic analysis of 16 carrier cows and two deformed calves showed normal karyotypes. Serology for Akabane virus in 16 carrier cows was negative.

Neuromuscular arthrogryposis multiplex congenita in a thoroughbred foal

Arthrogryposis multiplex congenita was studied in a newborn thoroughbred foal. The syndrome affected only the left hind limb allowing the right hind limb to serve as a reference. There was a significant depletion of large motor neurons from the ventral horn of the spinal cord from L3 to S4 on the affected side. Hypoplasia of nerves, muscles, and bones was present in the affected limb. Histologically, hypoplasia and degeneration of myofibers and nerve bundles were seen. No cause of the syndrome, which corresponds to most human cases, was determined. Neuromuscular arthrogryposis was diagnosed because of the difficulty in distinguishing primary neuropathic from primary myopathic forms of the disease.