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Monitoring of clinical signs in goats with transmissible spongiform encephalopathies.

Konold T, Bone GE, Phelan LJ, Simmons MM, González L, Sisó S, Goldmann W, Cawthraw S, Hawkins SA - BMC Vet. Res. (2010)

Bottom Line: The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.Signs of pruritus were not always present despite similar prion protein genotypes.PrPd accumulation in the brain appeared to be related to the severity of clinical disease but not to the display of individual neurological signs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, KT15 3NB, UK. t.konold@vla.defra.gsi.gov.uk

ABSTRACT

Background: As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.

Results: The sensitivity and specificity of the short clinical protocol in detecting a scrapie case in the scrapie-affected herds was 3.9% and 99.6%, respectively, based on the presence of tremor, positive scratch test, extensive hair loss, ataxia and absent menace response. All BSE- and scrapie-affected goats displayed abnormalities in sensation (over-reactivity to external stimuli, startle responses, pruritus, absent menace response) and movement (ataxia, tremor, postural deficits) at an advanced clinical stage but the first detectable sign associated with scrapie or BSE could vary between animals. Signs of pruritus were not always present despite similar prion protein genotypes. Clinical signs of scrapie were also displayed by two scrapie cases that presented with detectable disease-associated prion protein only in lymphoid tissues.

Conclusions: BSE and scrapie may present as pruritic and non-pruritic forms in goats. Signs assessed for the clinical diagnosis of scrapie or BSE in goats should include postural and gait abnormalities, pruritus and visual impairment. However, many scrapie cases will be missed if detection is solely based on the display of clinical signs. PrPd accumulation in the brain appeared to be related to the severity of clinical disease but not to the display of individual neurological signs.

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Timeline of clinical progression in scrapie-affected goats. Each column of symbols for one animal represents a time point when an examination was carried out in this particular animal. Days after arrival refers to the days after transport to VLA Weybridge. Only the first animal (GZ1100, herd A) was a clinical suspect reported by the farmer whereas the other goats arrived without clinical suspicion as part of the herd cull (herd B). The latter goats displayed no apparent signs (G08-1475, G08-1396) or inconclusive signs of scrapie (G08-1447: head tremor, over-reactivity to handling, G08-1373: hind limb tremor) or were considered scrapie suspects [G08-1460: positive scratch test, repeated over-reactivity to auditory stimuli (hand clapping), G08-1430: positive scratch test] based on the short clinical assessment.
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Figure 1: Timeline of clinical progression in scrapie-affected goats. Each column of symbols for one animal represents a time point when an examination was carried out in this particular animal. Days after arrival refers to the days after transport to VLA Weybridge. Only the first animal (GZ1100, herd A) was a clinical suspect reported by the farmer whereas the other goats arrived without clinical suspicion as part of the herd cull (herd B). The latter goats displayed no apparent signs (G08-1475, G08-1396) or inconclusive signs of scrapie (G08-1447: head tremor, over-reactivity to handling, G08-1373: hind limb tremor) or were considered scrapie suspects [G08-1460: positive scratch test, repeated over-reactivity to auditory stimuli (hand clapping), G08-1430: positive scratch test] based on the short clinical assessment.

Mentions: Of the 24 goats from herd B that were kept for monitoring of clinical progression or milk collection, eight were scrapie-negative on postmortem tests: four continued to show no apparent signs of scrapie and four showed inconclusive signs prior to cull (see Table 3). The remaining 16 scrapie-infected goats (see Table 4) were or became clinical suspects on or after arrival at VLA (six goats, also included in. Figure 1), developed inconclusive signs of scrapie (seven goats) or continued to show no apparent signs of scrapie prior to cull (three goats).


Monitoring of clinical signs in goats with transmissible spongiform encephalopathies.

Konold T, Bone GE, Phelan LJ, Simmons MM, González L, Sisó S, Goldmann W, Cawthraw S, Hawkins SA - BMC Vet. Res. (2010)

Timeline of clinical progression in scrapie-affected goats. Each column of symbols for one animal represents a time point when an examination was carried out in this particular animal. Days after arrival refers to the days after transport to VLA Weybridge. Only the first animal (GZ1100, herd A) was a clinical suspect reported by the farmer whereas the other goats arrived without clinical suspicion as part of the herd cull (herd B). The latter goats displayed no apparent signs (G08-1475, G08-1396) or inconclusive signs of scrapie (G08-1447: head tremor, over-reactivity to handling, G08-1373: hind limb tremor) or were considered scrapie suspects [G08-1460: positive scratch test, repeated over-reactivity to auditory stimuli (hand clapping), G08-1430: positive scratch test] based on the short clinical assessment.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2875668&req=5

Figure 1: Timeline of clinical progression in scrapie-affected goats. Each column of symbols for one animal represents a time point when an examination was carried out in this particular animal. Days after arrival refers to the days after transport to VLA Weybridge. Only the first animal (GZ1100, herd A) was a clinical suspect reported by the farmer whereas the other goats arrived without clinical suspicion as part of the herd cull (herd B). The latter goats displayed no apparent signs (G08-1475, G08-1396) or inconclusive signs of scrapie (G08-1447: head tremor, over-reactivity to handling, G08-1373: hind limb tremor) or were considered scrapie suspects [G08-1460: positive scratch test, repeated over-reactivity to auditory stimuli (hand clapping), G08-1430: positive scratch test] based on the short clinical assessment.
Mentions: Of the 24 goats from herd B that were kept for monitoring of clinical progression or milk collection, eight were scrapie-negative on postmortem tests: four continued to show no apparent signs of scrapie and four showed inconclusive signs prior to cull (see Table 3). The remaining 16 scrapie-infected goats (see Table 4) were or became clinical suspects on or after arrival at VLA (six goats, also included in. Figure 1), developed inconclusive signs of scrapie (seven goats) or continued to show no apparent signs of scrapie prior to cull (three goats).

Bottom Line: The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.Signs of pruritus were not always present despite similar prion protein genotypes.PrPd accumulation in the brain appeared to be related to the severity of clinical disease but not to the display of individual neurological signs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Neuropathology, Veterinary Laboratories Agency Weybridge, New Haw, Addlestone, KT15 3NB, UK. t.konold@vla.defra.gsi.gov.uk

ABSTRACT

Background: As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.

Results: The sensitivity and specificity of the short clinical protocol in detecting a scrapie case in the scrapie-affected herds was 3.9% and 99.6%, respectively, based on the presence of tremor, positive scratch test, extensive hair loss, ataxia and absent menace response. All BSE- and scrapie-affected goats displayed abnormalities in sensation (over-reactivity to external stimuli, startle responses, pruritus, absent menace response) and movement (ataxia, tremor, postural deficits) at an advanced clinical stage but the first detectable sign associated with scrapie or BSE could vary between animals. Signs of pruritus were not always present despite similar prion protein genotypes. Clinical signs of scrapie were also displayed by two scrapie cases that presented with detectable disease-associated prion protein only in lymphoid tissues.

Conclusions: BSE and scrapie may present as pruritic and non-pruritic forms in goats. Signs assessed for the clinical diagnosis of scrapie or BSE in goats should include postural and gait abnormalities, pruritus and visual impairment. However, many scrapie cases will be missed if detection is solely based on the display of clinical signs. PrPd accumulation in the brain appeared to be related to the severity of clinical disease but not to the display of individual neurological signs.

Show MeSH
Related in: MedlinePlus