Changes

==Clinical Signs==  

==Clinical Signs==  

Early clinical signs may include subtle behavioural changes such as staring or fixed gaze, teeth grinding (bruxism), fine tremor, and hyperaesthesia to sound or sudden movements. Affected animals may later become intolerant to exercise and develop ataxia (awkwardness at turning, swaying of the hindquarters and some gait abnormalities such as a high stepping gait in the forelimbs or a bunny hopping gait in the hindlimbs). Some sheep have intense pruritis that leads to compulsive rubbing, nibbling at the skin, or scraping against fixed objects and may lead to wool loss (especially over the hindquarters and lateral thorax). A characteristic lip smacking or nibbling reflex can often be elicited by scratching over the lumbar region. In later stages there can be significant weight loss even without a noticeable decrease in appetite, weakness, recumbency, and death. <ref name="Bradley, 1997"> Bradley R, 1997. Animal prion diseases. In: Collinge J, Palmer MS, eds. Prion diseases. Oxford, UK: Oxford University Press, 89-129.</ref>, <ref name="Dickinson, 1976"> Dickinson AG, 1976. Scrapie in sheep and goats. Frontiers in Biology, 44:209-241</ref>, <ref name="Kimberlin, 1981"> Kimberlin RH, 1981. Scrapie. British Medical Journal, 137:105-112.</ref>, <ref name="Palmer, 1976, "> Palmer AC, 1976. Scrapie. In: Palmer AC, ed. Introduction to animal neurology. Oxford, UK: Blackwell Scientific Publications, 177-178.</ref>, <ref name=" Parry and Oppenheimer, 1983" />.  It is important to note that some scrapie-infected sheep may appear healthy until stressed by  transport, shearing, or pregnancy <ref name="Detwiler and Baylis, 2003" />.

Early clinical signs may include subtle '''behavioural and neuorological changes'''.  Sheep often have a fixed gaze, and suffer from bruxism, fine tremors, and hyperaesthesia to sound or sudden movements. Affected animals may later become exercise intolerant and develop progressive ataxia.  Sheep often find difficulty in turning, sway on their hind hindquarters and have gait abnormalities such as a high stepping gait in the forelimbs or a bunny hopping gait in the hindlimbs. Some sheep have intense pruritis that leads to compulsive rubbing, nibbling at the skin, or scraping against fixed objects.  Wool loss is typically seen over the hindquarters and lateral thorax. Lip smacking or nibbling reflex can often be elicited by scratching over the lumbar region, which is characteristic og scrapie. Significant weight loss with or without a decrease in appetite, weakness, recumbency, and death are all seen within the later stages of the disease.  

==Diagnosis==

==Diagnosis==