Suspected inherited cerebellar neuroaxonal dystrophy in collie sheep dogs

A cerebellar neuroaxonal dystrophy in working collie sheep dogs from two properties in New Zealand and one property in Australia is described. Clinical signs developed from 2–4 months of age and included hypermetria, wide-based stance, difficulty in maintaining balance, intention tremor and ataxia. Numerous spheroids, associated with mild Wallerian degeneration, were present in the central cerebellar, adjacent peduncular and folia white matter, and associated cerebellar roof and lateral vestibular nuclei. The history of several affected pups in litters from successive matings of the same sire and dam is suggestive of an autosomal recessive mode of inheritance.     

Suspected inherited cerebellar neuroaxonal dystrophy in collie sheep dogs

A cerebellar neuroaxonal dystrophy in working collie sheep dogs from two properties in New Zealand and one property in Australia is described. Clinical signs developed from 2-4 months of age and included hypermetria, wide-based stance, difficulty in maintaining balance, intention tremor and ataxia. Numerous spheroids, associated with mild Wallerian degeneration, were present in the central cerebellar, adjacent peduncular and folia white matter, and associated cerebellar roof and lateral vestibular nuclei. The history of several affected pups in litters from successive matings of the same sire and dam is suggestive of an autosomal recessive mode of inheritance.     

A fodder mycotoxicosis of ruminants caused by contamination of a distillery by-product with Aspergillus clavatus

Cattle and sheep, grazed successively on the same pasture and given the same supplementary feeding, developed ataxia and several animals became recumbent. Three cattle died within two weeks and the worst affected sheep were killed for laboratory examination. The supplementary diet which consisted largely of a distillery by-product, malt culms, was submitted for mycological examination and fed to two housed lambs. Aspergillus clavatus was cultured from the culms, and both the affected sheep and the housed lambs showed cerebrospinal degenerative changes. The clinical signs and neuropathology were closely similar to a mycotoxicosis, attributed to A clavatus, which is seen infrequently in cattle in France, Bulgaria, South Africa and China.     

Diagnosis of the nervous form of Maedi-Visna infection with a high frequency in sheep in Castilla y Leon, Spain

Between 1997 and March 2004, the nervous form, or visna, of maedi-visna infection was diagnosed in 71 of 1631 sheep (4.35 per cent) examined in the Castilla y León region of Spain, of which 634 had shown nervous signs. The presence of the virus was confirmed by immunohistochemistry and in some cases by pcr on frozen-thawed or paraffin-embedded tissue samples. The main clinical signs were hindleg ataxia and paresis, but blindness or nystagmus were also observed. Thirty-three of the affected sheep (46.5 per cent) were two years old or younger. The affected sheep showed variable degrees of a non-suppurative meningoencephalitis, and immunohistochemistry identified positive cells in all cases, with no relation to the intensity of the inflammatory lesion.     

The Shetland Islands scrapie monitoring and control programme: analysis of the clinical data collected from 772 scrapie suspects 1985-1997

There were 574 scrapie positive suspects (histopathological scrapie lesions present) and 198 scrapie negative suspects (histopathological scrapie lesions absent). The greatest number of scrapie cases were recorded in sheep of 2, 3 and 4 years of age which represented 17%, 36% and 23% of the scrapie positive suspects, respectively. The sign sensitivities and specificities for the ten recorded signs were, respectively: pruritus (62%, 42%), ataxia (23%, 74%), hyperaesthesia (32%, 74%), wool loss (25%, 73%), fleece discolouration (29%, 85%), bruxism (23%, 69%), nibbling reflex (17%, 58%), head rubbing (47%, 78%), poll rubbing (25%, 83%). These single signs had poor discriminatory values with likelihood ratios close to one (range 0.89-1.21); combinations of the four signs, pruritus, wool loss, ataxia, hyperaesthesia and emaciation were more discriminatory (range 0.30-4.3). This study covered a time period when bovine spongiform encephalopathy (BSE) might have been introduced into the sheep population on the Shetland Islands via contaminated feed. No temporal changes could be detected in the age structure of the affected animals.     

Intervertebral disc disease of the cervical and cranial thoracic vertebrae in equidae: eight cases

Intervertebral disc disease in the cervical and cranial thoracic vertebrae is unusual in horses and the majority of documented cases have been associated with infection and resulted in ataxia. The current retrospective study documents the clinical and imaging features, and outcome in eight Equidae with neck stiffness ± forelimb lameness (n = 3) or ataxia (n = 2) assessed during a 10-year period at two clinics. The Equidae (one donkey and seven horses) ranged in age from 1.5 to 12 years (median 5.5 years). The duration of clinical signs ranged from 1 to 6 months (median 1.5 months). The donkey had a depressed demeanour. All Equidae had reduced range of neck movement. The donkey and one horse showed mild and severe ataxia respectively. Two horses showed a propensity to stumble on each forelimb, one of which exhibited forelimb lameness on the lunge or ridden. Two additional horses showed lameness in hand. One horse experienced ‘neck locking’ during grazing. Radiological abnormalities were identified involving the intervertebral symphysis between the sixth cervical vertebra (C6) and C7 in four Equidae; in two horses the articulation between C7 and the first thoracic vertebra (T1) was involved. One horse had abnormalities of the intervertebral symphyses of both C7 and T1, and T1 and T2. In one horse the articulation between C2 and 3 was affected. The donkey was treated with a prolonged course of doxycycline and improved. An advanced dressage horse returned to full-function after surgical fusion of the affected intervertebral symphysis. Intervertebral disc disease is a rare cause of neck stiffness ± lameness or ataxia.     

Cerebellar abiotrophy and segmental axonopathy: two syndromes of progressive ataxia of Merino sheep

Findings of a study of 39 sheep with progressive ataxia from 14 farms in the Yass district of New South Wales are described. Microscopic lesions in 25 sheep, 3.5 to 6 years of age, diagnosed as having clinical cerebellar disease, consisted of an apparent primary loss of cerebellar Purkinje neurons, and glial cell accumulation. It is suggested that this previously unreported disorder may be an hereditary cerebellar abiotrophy of Merino sheep. A further 14 sheep, 1 to 4 years of age, had distinguishable clinical signs referable to a spinal cord lesion with widespread segmental axonal ballooning, or "spheroids", in the white matter of the brain and spinal cord. It is suggested that these sheep have a unique form of neuroaxonal dystrophy, described here as segmental axonopathy, and that this is likely to be the same condition described previously as Murrurindi disease (Hartley and Loomis 1981).     

Cycad (zamia) poisoning in Australia

The Cycads belong to an ancient family of plants and were the cause of the first well documented plant poisoning in Australia when Captain Cook's men and their pigs were affected by eating them. Subsequent reports particularly by early explorers refer to toxicity of the seeds to man. One reason for this was the evidence that the natives ate them. Subsequent reports and experimental work established the toxicity to sheep and cattle. In sheep and cattle 2 syndromes occur, ataxia and liver damage. In cattle the former is the better known, the spinal cord lesion being mainly a demyelination of the sensory pathways. The liver damage is necrosis and fibrosis.     

Cervical and Thoracic Vertebral Malformation ("Weak Neck") in Colombia Lambs

The purpose of this study is to describe a developmental defect of the caudal cervical and cranial thoracic vertebrae in 11 purebred Colombia lambs. The lambs were either affected at birth, or developed the condition within the first 18 days of age. Cervicothoracic kyphosis, with a compensatory cervical lordosis and ataxia were common; 8 lambs had abnormal head posture, characterized by inability to lift the head from the ground. One lamb had rigid head and neck, and had to move the entire body to look to the left or right. Neurological signs included ataxia, tetraparesis, diminished conscious proprioception, and increased patellar and triceps reflexes. One lamb had inspiratory stridor because of compression of the trachea in the area overlying the abnormal vertebrae (cervical vertebrae 6 [C6] and 7 [C7]). Radiographic and pathological abnormalities included malalignment and malarticulation of the caudal cervical and cranial thoracic spine, rounded cranioventral margins in the bodies of vertebrae C7 and T1, wedging of the intervertebral disc spaces between C6 and T1 vertebrae, and hypoplasia of the dens. Pathological changes in the soft tissues included hypoplasia of the cervical epaxial and hypaxial musculature, with associated focal areas of myodegeneration. Mild Wallerian axonal degeneration, compatible with a mild cord compression syndrome, was found in 3 lambs in the cervicothoracic spinal cord adjacent to the vertebral anomalies. The concentrations of copper and selenium in blood, plasma, or tissues were normal in 10 of 11 lambs. All but one of the lambs in which pedigree information was provided were genetically related. Siblings born as twins to 5 of the affected lambs were normal, but both lambs from one twin pregnancy were affected. Owners reported that breeding stock had been shared among the ranches. Because of the close familial relationships of the affected lambs, the condition is suspected to have a hereditary basis.     

Compressive cervical myelopathy in young Texel and Beltex sheep

BACKGROUND: This investigation was prompted by the referral of increasing numbers of young Texel and Beltex rams with ataxia and weakness, or wobbler syndrome. HYPOTHESIS: The study aims were to describe the clinical and pathologic findings in affected sheep. ANIMALS: The animals evaluated in this study included 7 Texel sheep (6 male and 1 female) and 3 Beltex sheep (2 male and 1 female) referred from pedigree flocks. Typically, the sheep were 15-18 months of age at referral. METHODS: Diagnostic investigations included radiographic and computed tomographic (CT) myelography followed by gross postmortem and histopathologic examinations. RESULTS: Clinical findings typical of cervical spinal cord compression were present in all sheep but varied in severity. Myelography confirmed dorsal spinal cord compression in the region of C6-C7. No bony abnormalities were identified as described in cases of canine and equine wobbler syndrome. Postmortem examinations revealed discrete, smooth, nodular to polypoid projections of adipose tissue apparently prolapsing through the dorsolateral intervertebral space at C6-C7 and causing localized spinal cord compression. Histopathology of the nodules confirmed that they were composed of well-differentiated adipocytes typical of fatty tissue. Spinal cord lesions were similar in all sheep with marked Wallerian degeneration at the site of compression and mild Wallerian degeneration present cranial and caudal to the lesion. CONCLUSIONS AND CLINICAL IMPORTANCE: The findings of this study suggest a novel cervical myelopathy in these sheep breeds caused by the presence of fatty nodules encroaching into the dorsal vertebral canal at C6-C7. Additional investigations are required to establish the etiology and possible hereditary risk factors for this unique clinicopathologic syndrome.     

Ovine neuroaxonal dystrophy in New Zealand

A condition of neuroaxonal dystrophy of Coopworth sheep is described. This was characterised clinically by progressive ataxia from weaning with collapse of hindquarters and ultimately death. One per cent to 10% of the lamb flock on three commerical farms were affected over several years. Histopathological features were bilateral spheroid formation in specific brain stem nuclei and in the dorsal horn (especially in and about Clarke's column) along the length of the spinal cord. The condition appears virtually identical to that recorded earlier in Californian Suffolk sheep and that seen previously in the Romney, Perendale and Coopworth breeds in New Zealand. The cause was undetermined but it is suggested there may be an inherited component, as has been postulated in the Suffolks.     

Familial episodic ataxia in lambs

Abstract

HISTORY: A similar episodic neurological disorder occurred in new born lambs on two unrelated properties involving disparate breeds of sheep. Because of the number of lambs born, cross-breeding and the fact it occurred in some mating groups and not others, a dominant mode of inheritance was, initially and separately, suspected in each case. The sires of affected lambs were apparently normal. Whereas one was New Zealand Romney, the other was a composite breed with East Friesian genetics, but both rams originated from the same source property. To investigate the pathogenesis of the disorder these two rams were acquired and mated with unrelated sheep, under experimental conditions in a more controlled environment.

CLINICAL FINDINGS: A proportion of lambs born to both sires exhibited a similar neurological disorder. Some lambs were noted to be abnormal at birth, both on home properties and in the experimental flock. They tended to adopt a head and neck extended posture and were slow to get to their feet and suckle when they then became more or less normal. When forced to move, they and other more robust lambs elicited an asymmetric gait, base-wide extensor hypertonia (hypometria) of thoracic limbs and flexor hypertonia (hypermetria) of pelvic limbs. In some there was nystagmus. After several metres of asymmetric ataxic gait they would fall to one side, sometimes adopting a sitting position. Recovery usually occurred in one to several minutes. As lambs aged, it became more difficult to elicit the episodes of dysfunction and by 6 months of age they appeared normal.

DIAGNOSIS: The disorder was diagnosed as a dominant familial episodic cerebellovestibular ataxia inherited as a dominant trait, with incomplete penetration of observed clinical signs and variable expressivity.

CLINICAL RELEVANCE: A proportion of affected lambs are likely to die in the neonatal period so the specific nature of the disorder may go unrecognised. Because of incomplete penetrance and varying expressivity, many of the lambs carrying this mutation will survive without showing clinical signs and may enter breeding flocks, where the disorder may be perpetuated and contribute to neonatal deaths.     

A tremorgenic mycotoxicosis of cattle caused by maize sprouts infested with Aspergillus clavatus

An outbreak of disease affecting a herd of 16 dairy cattle which were fed mouldy, sprouted maize is described. Eight of the cattle were affected, 5 of which died. The clinical signs included muscular tremors, hypersensitivity, ataxia, anorexia and salivation. Aspergillus clavatus was the only fungus isolated from the sprouts. Clinical signs that were indistinguishable from those in the field outbreak were reproduced by dosing the mouldy maize sprouts to a steer and a sheep, and by dosing another sheep with maize inoculated with a pure culture of A. clavatus isolated from the mouldy maize on the farm. Light microscopical examination revealed neuronal degeneration and necrosis in the midbrain, medulla oblongata and spinal cord of all 3 of these animals. The disease is clinically and pathologically indistinguishable from the disease caused by the ingestion of sorghum beer residue, and in certain respects it is similar to toxicoses caused by the ingestion of wheat sprouts and malt sprouts infested with A. clavatus.     

Staggers induced by consumption of perennial ryegrass in cattle and sheep from northern California

Staggers was diagnosed in sheep and cattle from the northern California coast. The diagnosis was made on the basis of history of ingestion of perennial ryegrass (Lolium perenne) stubble, clinical signs of transient ataxia, which was aggravated by stimulation, and nearly complete recovery after removal of ryegrass as the primary forage. Morbidity was high, but death did not occur in any affected animals. The toxic endophyte, Acremonium lolii, was in most lower leaf sheaths from the ryegrass. Injection of extracts of the ryegrass from affected farms into mice induced signs of toxicosis. Additionally, ryegrass from all 3 farms contained the tremorgenic mycotoxin, lolitrem-B.     

Cerebellar abiotrophy in crossbred cattle

Cerebellar abiotrophy affected 9 of 74 calves sired by a Poll Hereford bull over 2 successive calving seasons. The disease was characterised by episodes of recumbency and ataxia, with hypermetria and wide base stance. Clinical signs commenced between birth and 8 months of age. Two calves which were affected first at 8 months of age recovered clinically 9 months later. Histological lesions were found in the cerebellar cortex of 7 calves and consisted of segmental degeneration and loss of Purkinje cells, and axonal swellings. The clinical signs and pathological findings were consistent with bovine familial convulsions and ataxia, which has not been described previously in Australia. The clinical signs were not attributable to the lesions observed in the cerebellum and an underlying electrophysiological abnormality is proposed. The aetiology of the condition is probably genetic and appears to have a multifactorial basis.     

Suckling calves with symptoms of swayback

Within a 1-year period, three calves from the same herd developed ataxia of the hind limbs and urinary incontinence at about 6 months of age. Signs progressed and the calves were slaughtered 1-8 months after the onset of signs. The calves belonged to a suckling beef herd of 35 cattle. Blood samples from 11 cattle of different ages were collected and glutathione peroxidase and copper levels were measured. Glutathione peroxidase levels were below the normal range in all cattle and copper levels were below the normal range in 7 of ll cattle. Pathological examination of an affected calf revealed a Wallerian type of degeneration of myelinated nerve fibres in the lateral and ventral spinal cord tracts. In addition, the hepatic copper content was very low. Copper deficiency is a well-known cause of swayback in young sheep and goats. To our knowledge, this is the first report of a possible association between a swayback-like syndrome and copper deficiency in calves.     

The effects of road transportation on physiological responses and meat quality in sheep differing in age

The aim of this study was to determine the effects of 8 h of road transportation on physiological responses and meat quality traits of sheep at 6, 12, and 24 mo of age. Seventy-two male sheep were equally divided into transported (TRANS) and nontransported (CON) treatments (n = 36), and each treatment was subdivided into 3 groups by age (n = 12). Sheep in CON groups were weighed, blood sampled, and slaughtered, whereas sheep in TRANS groups were weighed, transported, blood sampled, and slaughtered to collect meat samples. The BW of sheep in TRANS groups was reduced significantly (P < 0.001) compared with CON sheep, and older sheep lost more BW than younger animals. However, dressing percentages of TRANS sheep were significantly (P < 0.001) greater than those of CON sheep. Some meat quality variables were affected by transportation, and responses of different ages of sheep varied. Total pigment content and lipid oxidation of LM and gluteus medius of TRANS sheep increased significantly (P < 0.001) compared with CON sheep. Cooking loss of LM and gluteus medius was influenced significantly (P < 0.01) by interaction effect between transportation and age, and the values for 6-mo-old TRANS sheep were less than those of CON sheep. Serum total protein (P = 0.036), globulin (P = 0.026), triglyceride (P < 0.001), and total cholesterol concentrations (P = 0.028) of TRANS sheep decreased compared with CON sheep. Serum NEFA concentration of TRANS sheep increased in relation to CON sheep with a significant interaction (P < 0.001) between transportation and age effect. Numbers of white blood cells were influenced (P = 0.002) by an interaction effect between transportation and age, and values for 6-mo-old sheep were not influenced by transportation. Numbers of platelets were influenced (P = 0.014) by age; they decreased more in 6-mo-old sheep than in older sheep. Transportation and age had no significant effects (P > 0.05) on packed cell volume and lymphocyte number. Serum creatine kinase activities in TRANS sheep were affected (P = 0.01) by an interaction effect between transportation and age. The 2-thiobarbituric acid reactive substances in serum of TRANS sheep increased (P = 0.009) with the greatest change for 6-mo-old compared with older sheep. In conclusion, 8 h of road transportation resulted in greater heme pigment concentrations but improved meat tenderness and induced physiological responses of sheep. However, different ages of sheep showed different responses to the present transportation pattern.     

Natural scrapie in goats: case histories and clinical signs.

The case histories of the 20 goats affected with natural scrapie which have been examined since 1975 at the Central Veterinary Laboratory, Weybridge, are reviewed. Their ages ranged from two to seven years (median three years, four months) and 85 per cent of them were between two and four years old. The most common clinical signs were hyperaesthesia, ataxia and pruritus. The histories indicated that scrapie can occur in goats which have not been in contact with sheep.     

COMPUTED TOMOGRAPHY OF RAMBOUILLET SHEEP AFFECTED WITH NEURONAL CEROID LIPOFUSCINOSIS

Computed tomography (CT) was performed on 3 normal Rambouillet sheep and 6 Rambouillet sheep affected with neuronal ceroid lipofuscinosis. Characteristic lesions seen in the brain of affected sheep included dramatically enlarged lateral ventricles and reduced cerebral thickness. The lesions were seen in sheep as young as 4 months of age. Antemortem CT observations correlated well with postmortem findings in this model of Neuronal Ceroid Lipofuscinosis.