Congenital occipitoatlantoaxial malformations in the horse

From a clinical, radiological and morphological study of 9 horses with congenital malformations of the occiput, atlas and axis, and from a study of 2 reported cases, 3 diseases were defined: A. Familial occipitalisation of the atlas with atlantalisation of the axis in Arabian horses (7 cases in this report and the case reported by Leipold, et al., 1974). These horses had congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis and modification of the atlantoaxial joint. B. Congenital asymmetrical occipitoatlantoaxial malformation (2 cases in this report). A Standardbred and a Morgan horse had atlantooccipital fusion, a wedge shaped vertebral piece attached to the caudal end of the axis and sigmoid scoliosis of the cervical vertebrae. C. Asymmetrical atlantooccipital fusion (the case reported by Schmaltz, 1915). This horse of an unknown breed had asymmetrical fusion between the atlas and occiput and cervical scoliosis. The clinical syndromes shown by horses with these malformations were variable but were broadly classified as: 1. Foal dead at birth, seen in one foal with A. 2. Tetraparesis at birth, seen in 5 foals with A. These foals were born with signs varying from tetraparesis to tetraplegia. 3. Progressive ataxia, seen in 2 foals with A. Clinical signs were due to a progressive focal cervical compressive myelopathy. 4. Congenital cervical scoliosis/deviated head, seen in the 2 horses with B and the horse with C. These horses had no signs of spinal cord or brain disease. The diagnoses were made clinically by palpation of the occipitoatlantoaxial region and were confirmed radiographically and/or by post mortem examination in all except one case. Pedigree analysis showed the familial nature of the particular occipitoatlantoaxial malformation seen in horses of only the Arabian breed.     

Vascular malformations and hemangiomas of the canine spinal cord.

An arteriovenous malformation and two hemangiomas in the canine spinal cord were found in three dogs. The malformation was ventral, extramedullary and largely subdural. Chronic hypoxia, consequent upon the shunt, had led to extensive local edema, necrosis and hemorrhage at T13-L1. Prominent intramedullary perivascular fibrosis, mineralization and obliteration were the presumed consequences of the hemodynamic insult. The hemangiomas, one of which was multiple, were deep lesions that produced compressive changes in the adjacent cord tissue. The masses were regarded as benign neoplasms with central sclerosis. These conditions appear not to have been reported previously in the dog.     

The differential diagnosis of spinal cord malformations in cattle

Hereditary developmental disorders of the CNS, especially spinal cord, are of increasing importance in the bovine species. Therefore, congenital spinal malformations of non-hereditary origin have to be ruled out by carefully directed neuromorphological procedures. The two cases of malformation of the spinal cord reported were not accompanied by vertebral defects: The first one represents a complete diplomyelia of the caudal lumbo-sacral medulla in an 18 months old Brown Swiss heifer, the second one a circumscribed hydromyelia of the fifth lumbal segment, based on an incomplete dysraphic defect, in a 4 months old male German Simmental calf. Problems of diagnostic measures and of terminology, concerning differentiation between diplomyelia and diastematomyelia, were discussed in detail.     

Congenital caudal vertebral malformations in the alpaca (Lama pacos)

OBJECTIVE: To assess radiologically the caudal vertebrae of a male alpaca with an abnormal tail, and nine of his offspring. PROCEDURE: Right lateral and ventrodorsal radiographs were taken of the caudal vertebrae. RESULTS: The caudal vertebral abnormalities in these alpacas included vertebral subluxation, hemivertebrae, wedge hemivertebrae and block vertebrae. CONCLUSION: These malformations in offspring of one sire suggest a hereditary basis for congenital caudal vertebral malformations in the alpaca.     

Congenital spinal stenosis in beef calves in western Canada

Nineteen calves with a clinical history of posterior weakness or ataxia were examined at necropsy. Dorsoventral narrowing of the vertebral canal and myelopathy were found in the thoracic and lumbar areas of the spinal cord; vertebral metaphyseal growth plates had focal areas of premature closure. Malformation of the cranial base and hydrocephalus were also observed. Shortening of long bones and malformation of long bone epiphyses were prominent findings and were associated with focal premature closure of metaphyseal growth plates. The cause of these lesions is unknown; possible causes, including a maternal deficiency of manganese, are discussed.     

Congenital malformations in sheep resulting from in utero inoculation of Cache Valley virus

Serologic evidence indicated that an episode of congenital abnormalities in sheep was caused by Cache Valley virus (CVV), a bunyavirus indigenous to the United States. To determine the teratogenic potential of CVV in sheep, fetuses were infected in utero between 27 and 54 days of gestation with an isolate (CK-102) obtained in 1987 from a sentinel sheep in San Angelo, Texas. The dams of these fetuses were euthanatized between 28 and 75 days after inoculation, and the fetuses were examined for malformations. Twenty-eight of 34 fetuses had congenital abnormalities, including arthrogryposis, hydranencephaly, mummification, reabsorption, and oligohydroamnion. Virus was isolated from the allantoic fluid of 11 of 17 fetuses euthanatized at less than 70 days of gestation. The virus-positive fetuses, which were all negative for CVV-neutralizing antibody, had lesions ranging from none to severe arthrogryposis and hydranencephaly. Virus was not recovered from the allantoic fluid of fetuses after 76 days' gestation when CVV-specific antibody could be detected in 5 of 8 fetuses examined. The 2 fetuses infected on days 50 and 54 of gestation appeared normal and 1 had antibody to CVV.     

Dermoid sinus and spinal malformations in a Yorkshire terrier: Diagnosis and follow-up

An unusual case of a Yorkshire terrier with a dermoid sinus associated with multiple spinal/costal malformations is described. The dog presented with ataxia and pain in the dorsal thoracic region. Diagnostic characterisation of the lesions was obtained with radiography, myelography and computed tomography. After surgical removal of the sinus, the dog showed marked clinical improvement over a two-year period.     

Congenital Neospora caninum infection in a calf with spinal cord anomaly

Neospora caninum was identified in a calf with spinal cord anomaly in Australia. The calf was full-term and born dead. The caudal cervical and cranial thoracic segments of the spinal cord of the calf were asymmetric because of marked unilateral reduction of ventral gray matter and focal cavitation. Mild focal disseminated nonsuppurative encephalomyelitis was associated with N caninum tissue cysts. Tissue cysts were 16 to 35 microns X 10 to 27 microns, and the cyst walls were 1 to 3 microns thick. In an immunohistochemical test, the parasite stained with N caninum serum but not T gondii serum.     

Congenital malformations of the tricuspid valve in domestic carnivores: a retrospective study of 50 cases

A retrospective study was done on 14 cats and 36 dogs diagnosed with right atrioventricular valve malformations (RAVM), either tricuspid dysplasia (n = 38) or Ebstein's anomaly (n = 12). Comparison with a large reference population including 85 250 animals allowed an epidemiologic analysis of these RAVM, demonstrating that Labrador, Boxer and Chartreux cats had a 35, 7 and 11-fold higher risk respectively to be affected by one of these heart diseases than other breeds, without sexual predisposition. In 93% of cases, cardiac auscultation revealed a heart murmur, whose grade was not significantly correlated with the echographic stages of the valvular disease. The echocardiographic examination confirmed the frequent association between RAVM and other congenital anomalies, particularly mitral dysplasia, in 84% and 20% of tricuspid dysplasia and Ebstein anomaly respectively. Last, the prognosis of RAVM was worsened by atrial fibrillation and right-sided heart failure.     

Congenital spinal stenosis and dam mortality associated with feeding moldy cereal straw

We describe herein an epidemiological investigation of the cause of a syndrome of congenital spinal stenosis (CSS) in four beef herds in western Canada. Three of the herds were affected with the syndrome in 1987, the fourth was affected in 1990. The prevalence of CSS in affected groups of calves varied from 29% (16/55) to 100% (14/14). All affected calves had congenital posterior paralysis or paresis; some calves also had one or more of the following: shortened limbs, forelimb varus deformities, superior brachygnathia, and a dome-shaped cranium. Affected calves showed focal premature closure of axial and appendicular metaphyseal growth plates. At three of the four farms most of the pregnant cows were affected with alopecia with or without pruritus in January, and 25% of the cows in one herd died during the winter. The investigation indicated that CSS was associated with feeding moldy cereal straw to pregnant beef cows during the winter. At all four farms, the cereal straw bales were thoroughly soaked by rain prior to stacking, and obvious mold was present when they were broken open for feeding. Species of both Penicillium and Fusarium were abundant within the bales. The most likely cause of the disease was a fungal mycotoxicosis, although the mycotoxin responsible was not isolated.     

Congenital ocular anomalies.

This discussion provides an idea of the diversity and relative prevalence of certain congenital ocular conditions of horses. Many are not difficult to diagnose, yet curative treatment may be impossible. When dealing with owners of horses affected with unusual anomalies, responsible client service requires veterinarians to provide accurate information and to know where answers to unusual questions can be found. Again, most veterinarians never encounter all of the diverse congenital defects. As a result, the horse owner frequently receives misinformation. Hopefully, this brief coverage of congenital ocular anomalies will provide useful information and assist in appropriate communication to concerned parties.     

Congenital skeletal malformations induced by maternal ingestion of Conium maculatum (poison hemlock) in newborn pigs

Skeletal malformations were induced in newborn pigs from gilts fed Conium maculatum seed or plant during gestation days 43 through 53 and 51 through 61. The teratogenic effects in groups dosed during gestation days 43 through 53 were more severe than those in groups dosed during the later period, with many newborn pigs showing arthrogryposis and twisted and malaligned bones in the limbs and with 1 pig showing scoliosis and deformity of the thoracic cage. The pigs born to gilts given C maculatum during gestation days 51 through 61 had excessive flexure primarily in the carpal joints, without scoliosis or bone malalignment in the limbs. The teratogenicity of poison hemlock depends on the alkaloid concentration and content. Based on the data presented, we speculate that gamma-coniceine is the teratogenic alkaloid in the poison hemlock fed to the gilts.