A Clinical, Pathological and Demographic Study of an Unusual Locomotor Disorder of Sheep

Clements, Archie C. A (2000) A Clinical, Pathological and Demographic Study of an Unusual Locomotor Disorder of Sheep. MVM(R) thesis, University of Glasgow.

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Abstract

Kangaroo Gait is a locomotor disorder of sheep, which was first described in New Zealand in 1978, and was subsequently reported in the United Kingdom, initially in 1986. The reported features of the condition included acute onset bilateral forelimb paresis in adult female sheep occurring during lactation or late gestation, Wallerian degeneration of the radial nerves, subsequent regeneration, and, in most cases, clinical recovery. The aetiology of Kangaroo Gait remained obscure and there was little information regarding the incidence, the geographical distribution or the economic importance of this condition. This study was undertaken with the aims of characterising Kangaroo Gait in northern Britain in terms of its clinical, pathological and demographic features. Thirteen adult female sheep from six flocks in south west Scotland, which had presented with an abnormal forelimb gait, were subjected to a clinical investigation, and four of these adult female sheep, as well as two lambs from one adult female, were submitted for pathological examination. The anamnesis for each flock did not reveal consistent problems with general management, nutrition, disease occurrence, or the presence of toxic plants or chemicals. Apart from the abnormal locomotion, physical examinations and ancillary investigations did not detect any consistent abnormalities. Neurological examinations resulted consistently in findings of bilateral forelimb paresis and reduced muscle bulk of the proximal forelimbs. Variable findings included proprioceptive deficits in the forelimbs and normal pedal withdrawal reflexes in all four limbs. A clinical diagnosis of Kangaroo Gait was determined for the 13 sheep. Evidence of Wallerian degeneration was found in the radial nerves of one adult female (onset of clinical signs during lactation), and minor changes were found in the radial nerves of a second (onset of clinical signs during gestation) but no significant abnormalities were detected in the peripheral nerves of the remaining adult females or the lambs. Non-specific changes were detected in the spinal cord of two adult females and the brain of one adult female (onset of clinical signs during gestation). Results suggested that Kangaroo Gait could occur in adult female sheep of a number of breeds, between the ages of one and seven years, onset of clinical signs could occur during late gestation or early to mid lactation, and recovery from clinical signs was not dependent on cessation of lactation. It was suggested that a range of pathological changes were associated with this condition, and that close observation of animals around the time of onset of clinical signs, and recruitment of individuals for detailed pathological examinations at that time, would be essential for determining the aetiopathogenesis of Kangaroo Gait. In order to gain more information, two questionnaire studies were undertaken. The first survey was mailed to veterinary surgeons in all practices in Northern Britain which, according to the Directory of Veterinary Practices (Hall, 1997), provided veterinary care for sheep, and the second was mailed to sheep flock owners and managers located in the Scottish Borders, who were recruited via veterinary surgeons. Response rates of 84.7% and 30.7% were achieved. In total, 29.7% and 24.1% of respondents had identified one or more cases of Kangaroo Gait in their practice area or flocks at some time. Almost all respondents who had identified cases indicated that adult females were affected, most often during lactation, and less commonly during late gestation. Results suggested that Kangaroo Gait was more common among commercial cross breeds, and was less common on hill farms than upland or lowland farms. The annual number of affected individuals and flocks had increased since the condition was first identified. Comparing the results of the two surveys revealed that a majority of cases of Kangaroo Gait and other locomotor disorders were not reported to veterinary surgeons. Further epidemiological investigations could prove useful in determining risk factors for the occurrence of Kangaroo Gait. However, it was suggested that economic crises in the UK sheep industry, accompanied by a perception that Kangaroo Gait is of little economic importance, make it unlikely that detailed studies of this condition will be conducted in the foreseeable future.

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Additional Information: Adviser: Julie Fitzpatrick
Keywords: Veterinary science, Animal diseases
Date of Award: 2000
Depositing User: Enlighten Team
Unique ID: glathesis:2000-76165
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 16:33
Last Modified: 19 Nov 2019 16:33
URI: http://theses.gla.ac.uk/id/eprint/76165

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