As scrapie is a neurological disease the clinical diagnosis should be based on a neurological examination. This is, however, time-consuming and not applicable when many animals have to be examined, e.g. at abattoirs. The short assessment protocol was designed to evaluate signs usually associated with classical or atypical scrapie in small ruminants, such as nervousness, pruritus, tremor, ataxia and poor bodily condition. The signs selected for identification of suspect cases (tremor, positive scratch test, extensive hair loss, ataxia and absent menace response) were highly specific but most of the scrapie cases would not have been detected using these criteria. This was to be expected since it has been shown previously that the postmortem tests are superior to a clinical examination of sheep in scrapie-affected flocks, even if limited to brain examination only . The conduction of the short clinical assessment lasted approximately five minutes per animal. After taking into account the signs that were significantly more frequent in confirmed scrapie cases in the herd cull (see Table 2) or seen at clinical end-stage in BSE or scrapie, it appears to be sufficient to assess animals for postural and gait abnormalities, signs of pruritus (scratch testing, hair loss predominantly on the poll and neck) and visual impairment (menace response testing).
As reported previously for herd B , evident (definite) signs of scrapie were found exclusively in goats homozygous for isoleucine at codon 142 of the caprine PRNP although one heterozygous (IM142) goat was initially considered to be a clinical suspect but the signs later regressed. Equally, all five clinical suspects reported by the farmer were I142 homozygotes, which suggests that scrapie in IM142 or MM142 goats may cause subclinical or a more protracted disease. BSE caused clinical disease in these PRNP genotypes but this may be due to the intracerebral route of infection. Although scrapie was diagnosed in goats of all breeds, clinical disease was not observed in the Alpine breed, but the number of clinically affected animals is too small to draw any conclusion on the effect of breed on the clinical presentation.
Contrary to TSE in cattle, where PrPd detection is almost entirely restricted to the CNS, small ruminants may present with PrPd in tissues of the LRS, some of which (tonsil, nictitating membrane and RAMALT) are accessible in the live animal. RAMALT samples, examined from goats in herd A (GZ1100 ), herd B  and BSE-affected goats did not always present with detectable PrPd despite PrPd accumulation in other tissues of the LRS. There is currently no evidence that PrPd accumulation in LRS produces clinical abnormalities since antemortem tests generally detect pre-clinical scrapie cases [27, 28], hence any animal with detectable PrPd in LRS only (35 cases in the present study) was likely to be missed as scrapie suspect. Two animals with detectable PrPd restricted to the LRS, however, displayed signs of scrapie. There are no pathognomonic clinical signs for scrapie (scrapie-like signs were also observed in goats without detectable PrPd in CNS or LRS, see Table 4) but the apparent clinical progression seen in these two goats (G08-1396: development of a positive scratch test on repeated examinations; G08-1430: consistent positive scratch test and later repeated display of over-reactivity to tactile stimuli) was consistent with scrapie although the lack of other signs suggested a less advanced clinical phase than in the CNS-positive goats. Either the signs were misleading, although we were unable to establish an alternative diagnosis, or scrapie can indeed produce clinical signs suggestive of CNS involvement in the absence of detectable PrPd in the CNS by current postmortem tests.
Circling, which was seen in one goat with scrapie when blindfolded and has also been described in one case report , is suggestive of an asymmetrical brain lesion whereas the neuropathological changes in caprine TSEs are generally bilateral symmetrical [10, 30]. Only half of the brain of the goat was available for histopathological examination, which prevented us from comparing the severity of lesions between both sides. Similarly, the magnitude of PrPd accumulation in the thalamus did not appear to be proportional to the frequency of pruritic behaviour or associated with a positive scratch test, even though thalamic lesions were considered to be responsible for the pruritus in caprine scrapie . There was some indication that extensive PrPd accumulation in the cerebellum was associated with more severe signs of cerebellar dysfunction but one animal with a similarly high score of PrPd deposits presented without any cerebellar signs. By contrast, the severity of clinical disease, i.e. the clinical status based on the frequency and severity of expressed clinical signs, appeared to be largely proportional to the total amount of PrPd accumulation in the brain, particularly in those scrapie-affected goats that were examined and observed repeatedly prior to cull: the scrapie case without evident clinical signs of scrapie had the lowest PrPd score compared to inconclusive cases or scrapie suspects. The goat with the widest range of clinical signs (G08-1447), however, was not the one with the highest PrPd score. Similarly, the mean PrPd score was lowest in the scrapie-affected goats without evident signs of scrapie that were only assessed once by the short protocol although the range in the PrPd score was more variable. This variability may be due to failure to detect some scrapie-associated signs using the short protocol only (e.g. pruritus) and the fact that some animals were culled up to 57 days after the short clinical assessment, during which time PrPd accumulation in the brain may have increased.
The sometimes poor correlation between clinical disease or clinical signs in particular and detectable PrPd accumulation in the brain, which has also been documented in other species, such as mice , cattle  and pigs , warrants further investigations into the cause of clinical abnormalities in TSEs.
The definition of excessive pruritic behaviour expressed as pruritus score and its cut-off value of 0.5 was arbitrary and not based on any published information. In addition, we only counted each event of pruritic activity and did not consider the duration of a pruritic session, which was usually brief (approximately 85% of these lasted less than 20 seconds). This may explain why a positive scratch test was not necessarily associated with excessive pruritus. A positive correlation between pruritus (based on wool loss) and scratch test response has been reported for Irish sheep with scrapie , whereas this was not found in British sheep where pruritus was based on the display of pruritic activity . The lack of "true" controls from a TSE-free herd - we only had exposed scrapie-negative goats - made it difficult to establish a baseline pruritic activity. In a behavioural study of sheep infested with Psoroptes ovis "increased rubbing" was defined as total time rubbing that was three standard deviations above the mean baseline rubbing time . If we defined a similar cut-off point by using the data from our very limited number of scrapie-free cases with available camera recordings none of the goats would have been pruritic due to the extremely high pruritic score of one of the scrapie-free goats. If this animal was excluded, the resulting cut-off point of 0.32 would have made almost every scrapie-positive goat excessively pruritic. In addition, other pruritic skin conditions may have existed in these goats, although we did detect ectoparasites macroscopically only in two goats and those that presented with skin conditions (crusts on ears suggestive of mange, ring-shaped hair loss suggestive of dermatomycosis but no further examination was carried out) did not display a positive scratch test. Ideally, each animal should have been kept under controlled, ectoparasite-free conditions and monitored pre- and post infection to assess changes in the pruritic activities individually but this would have only been possible in experimentally infected animals. Nevertheless, the low pruritus score in some animals (e.g. GX1030) suggests that indeed a non-pruritic form of TSEs exists in goats. The hair loss observed in many TSE-negative goats in the present study made this sign unreliable as indicator of pruritus. Unlike the Italian scrapie-affected goats that presented with thinning of hair, alopecia and skin lesions predominantly on the spinal region , this area was rarely affected in goats in the present study.
Signs that are reportedly frequent in goats with scrapie (in at least 80% of animals) are difficulty in milking and weight loss . Yet, a poor bodily condition was significantly more frequent in scrapie-negative goats, which may be due to other diseases that were not investigated as part of this study. Difficulty in milking in those goats that were milked was also more frequent in scrapie-negative goats. On the other hand, touching of the hind limbs, which may occur during milking, elicited kicking or restlessness in scrapie-affected goats, even on repeated examinations and in the vast majority of animals that were not considered to be over-reactive when the head was touched (data not shown). It was not known for both signs whether these were progressive changes, i.e. progressive loss of bodily condition and change in temperament characterised by recent difficulty in milking, because of the lack of any clinical history, which could explain why these signs did not appear to be particularly useful markers for scrapie in goats. However, comparison of the BCS between first and last clinical assessment in the 24 goats kept for a longer period did not even yield significant results between TSE-positive and negative animals (data not shown).
By contrast, weight loss was evident in four of five BSE-affected goats with a similar progression as reported for sheep with BSE  although the body condition score did not change. Weighing provides a more accurate estimation of loss of body mass but the problems of this technique, particularly in ruminants with the large amount of digesta in the gastrointestinal tract, has been highlighted .
Abnormal rising or delayed lying down was a behaviour that could have been easily missed if only clinical examinations were carried out. It is possible that conditions other than scrapie were responsible for this behaviour, for example diseases of the joints, which were not examined at necropsy. There was no clinical evidence for joint diseases although some of the goats had serum antibodies against Caprine Arthritis-Encephalitis Virus. This, however, included only one goat with abnormal rising or lying down (data not shown).
Previous experimental studies of scrapie in goats produced two different clinical phenotypes: the scratching syndrome with evident pruritic behaviour amongst other neurological signs and the nervous or drowsy syndrome where pruritus was generally absent [9, 10]. The findings in the present study suggest that the predominant clinical sign in goats with TSE at clinical end-stage is either a positive scratch test or ataxia without signs of pruritus, which is comparable to the pruritic and ataxic type of scrapie-affected sheep reported in Japan . Initial clinical signs may vary, with some animals presenting with a single sign over weeks (e.g. scrapie-affected goats G08-1373 and G08-1460), whereas others present simultaneously with a range of neurological signs (e.g. BSE-affected goat GX1035). It remains unknown what causes the difference in the clinical presentation but different scrapie strains, goat breeds and genotypes may account for the observed differences. Sheep infected with classical BSE appeared to develop a prion disease characterised by pruritus, which was regardless of prion protein genotype and route of inoculation (, T Konold, unpublished observation on further cases intracerebrally infected with BSE), and it was hypothesised that the clinical picture was mainly influenced by the strain. Scrapie-affected goats in herd B displayed pruritus whereas this was neither observed in any goat from herd A nor described by the farmer in previous cases on this farm, which may suggest that different strains may influence the clinical picture. Two of five goats, all of which were infected with the BSE agent, however, did not show any evidence of pruritus, and one of these displayed the drowsy form of the disease. This difference was unlikely to be caused by breed because all five goats were similar Saanen crossbreeds. It is possible that different polymorphisms of the caprine PRNP may influence the clinical presentation as it has been observed for sheep with scrapie [2, 20]. Several PRNP polymorphisms have been associated with susceptibility to infection and disease, including IM142, which produced an increased incubation period in BSE-infected goats . Although this genotype also seemed to increase the incubation period in the BSE-challenged goats in our study, it had no effect on the clinical presentation since both the pruritic and nervous or drowsy syndrome were found in IM142 goats. Similarly, both syndromes were also found in I142 homozygous scrapie-affected goats (e.g. Anglo-Nubian goat G08-1475: nervous syndrome; Alpine X Saanen goat G08-1147: scratching syndrome). Further studies would be required to assess whether other polymorphisms, not necessarily restricted to PRNP, may influence the clinical picture.
Drooling of saliva was observed only in one scrapie-affected goat whereas studies on a limited number of scrapie-affected goats in the UK and USA suggested that this sign was more frequent [4, 5]. In an Italian study of 500 goats, approximately 10% of the cases displayed salivation, which was seen in the terminal phase of the disease . Drooling of saliva accompanied by aspiration pneumonia may be suggestive of a dysfunction of the accessory, vagal and glossopharyngeal nerves . The jaw and tongue tone appeared normal in this goat; although the goat was seen eating hay attempts to make the animal swallow by palpation of the pharynx were unsuccessful.
Our findings in the BSE-affected goats were in disagreement with earlier reports that described it a disease with short clinical duration in the absence of pruritus [13, 14]. It is likely that the detailed clinical assessment, which included testing of the scratch response, enabled us to detect clinical cases earlier and document clinical signs that would have been missed under normal husbandry procedures. One intracerebrally infected goat presented with the drowsy form, which had previously only been reported for orally infected goats . As reported for sheep , the clinical presentation of BSE - based on the limited number of BSE-affected animals in the present study - and scrapie appears to be largely similar in goats, with some individual variability in the clinical presentation, whereas scrapie and BSE in cattle are clinically different . A deficient menace response was rare in scrapie-affected goats but it was displayed in three of five BSE-affected goats. Similarly, spontaneous head tossing during the examination was a sign predominantly seen in BSE-affected goats, possibly caused by disturbance of the trigeminal nerve sensory area as hypothesised for BSE in cattle . We cannot exclude that the intracerebral inoculation of the BSE cases may have affected the pathways involving the menace response or facial sensation although this is not supported by similar studies in sheep with BSE (rarely seen regardless of route of inoculation ) or atypical scrapie (menace response may be absent in naturally  and intracerebrally infected sheep [T Konold, unpublished observation]). The topographical distribution of neuropathological changes in experimentally infected goats was found to be consistent regardless of route of inoculation . The report of blindness in a goat with atypical scrapie  may justify the assessment of the menace response in goats.
The clinical presentation of scrapie in goats is usually described as similar to scrapie in sheep [44, 45] but specific differences seem to exist. Rubbing was reportedly more frequent in TSE-affected sheep than goats . The present study confirmed that nibbling of body parts was the most frequent pruritic activity in goats; in a separate study in 162 scrapie-affected sheep rubbing was most frequently observed (T Konold, unpublished observation). Sheep with scrapie were found to display hypoaesthesia in the limbs , whereas the kicking elicited by many TSE-affected goats when the hind limb were touched were suggestive of hyperaesthesia. Indeed, hyperaesthesia was considered more pronounced in goats than sheep with scrapie . In addition, repeated spontaneous startle responses observed in all BSE-affected goats and some scrapie-affected goats are rarely mentioned in sheep with scrapie whereas it occurs in BSE of cattle (T Konold, unpublished observation).