Name: Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep (Video) | JoVE Journal
Uploaded: 2014-01-19T14:00:00.000+00:00
Duration: 13 min 42 s
Description: Learn a five-minute clinical examination protocol to detect classical and atypical scrapie in sheep and goats. This method helps veterinarians identify neurological signs and improve early disease detection.

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5 minutes

The studies providing the animals were funded by the UK Department for Food, Environment and Rural Affairs and the European Union (through funding of the EU TSE Reference Laboratory). We acknowledge the support of the project managers, Dr. M. Simmons and Dr. M. Jeffrey.

1. Assessment of Posture
<ol>
	<li>Assess the posture of the animal whilst undisturbed.</li>
	<li>Animals affected by TSEs may stand with wide-based limbs, may appear hunched, or may stand with a low head carriage.</li>
</ol>
2. Assessment of Behavior
<ol>
	<li>Study the animal&#8217;s behavior, when left alone, when approached, and when handled.</li>
	<li>TSE-affected animals may display altered mentation by standing separately from other sheep or not immediately following other sheep.</li>
	<li>When the animal is approached, it may run away and collapses, or it collapses to the floor when handled. Compulsive clockwise or counter-clockwise circling may be seen in sheep with atypical scrapie.</li>
</ol>
3. Menace Response Testing
<ol>
	<li>Hold the animal&#8217;s head for testing of the menace response: move the hand or several fingers several times towards each eye of the animal to induce a blink response but be careful not to touch any facial hairs or create any air turbulence that may cause the animal to blink.</li>
	<li>The menace response may be absent in scrapie-affected animals, particularly in sheep with atypical scrapie. Although testing of the menace response is the only cranial nerve testing used as part of the protocol, visual inspection of the face during this procedure may reveal other signs of neurologic deficits not normally seen in scrapie, e.g. facial paralysis. If the animal does not blink in response to the menace it is advisable to test the palpebral reflex by touching the eyelids to ensure that the animal&#8217;s inability to blink is not caused by facial paralysis.</li>
</ol>
4. Testing of the Scratch Response
<ol>
	<li>Ensure the animal is calm during this procedure because the test cannot be interpreted in a struggling animal.</li>
	<li>Scratch areas of the back at the thoracic, lumbar, and sacral regions, pausing between each scratching episode.</li>
	<li>If the animal responds with rhythmical head or body movements, or moves or licks its lips upon scratching of one particular area, repeat the scratch test to confirm reproducibility of the scratch response.</li>
	<li>A repeatable response is usually elicited in animals that are pruritic, which usually includes sheep with classical scrapie or goats with the pruritic form of scrapie, but there is generally no response in sheep with atypical scrapie unless other pruritic skin conditions or ectoparasites are present.</li>
</ol>
5. Checking for Wool Loss and Skin Lesions
<ol>
	<li>Inspect the skin.</li>
	<li>Pruritus due to scrapie usually causes hair loss, which may be on the poll, back, rump, side of chest or abdomen due to excessive rubbing or scratching where the underlying skin appears normal.</li>
	<li>Abrasions may appear later if the animal has the opportunity to rub on sharp objects. Bite wounds may appear, particularly on the limbs, due to excessive nibbling of the limbs.</li>
</ol>
6. Scoring Body Condition
<ol>
	<li>Assess the animal&#8217;s body condition by palpating the dorsal and transverse processes of the lumbar vertebrae.</li>
	<li>Scrapie may cause a progressive loss of body condition where the transverse processes of the lumbar vertebrae can be easily felt individually, and the ends of the processes appear sharp.</li>
</ol>
7. Blindfolding the Animal
<ol>
	<li>Cover the animal&#8217;s eyes with a hood, which can be made by using any nonsee-through bag where one corner is cut off to allow breathing of the animal.</li>
	<li>Release the animal only if there are no safety concerns, and there is no risk of injury due to a panicking animal; otherwise keep hold of the sheep and study animal movements whilst still in control of the animal.</li>
	<li>Blindfolding may exacerbate signs of a vestibular system or cerebellar dysfunction, which may be obscured by the animal&#8217;s ability to compensate through its vision. Loss of balance, incoordination, or circling may be elicited, particularly in otherwise clinically unremarkable sheep with atypical scrapie.</li>
</ol>
8. Assessment of the Animal&#8217;s Movement
<ol>
	<li>Study the animal&#8217;s gait and muscle movements when it moves freely.</li>
	<li>Incoordination may be characterized by wide-based movements of the hind limbs, hopping with both hind limbs, or swaying excessively in the hind quarters, which may result in stumbling or briefly sitting down.</li>
	<li>The presence of a head tremor is often subtle when the animal is undisturbed but may become more noticeable during or after completion of the clinical examination.</li>
</ol>
9. Interpretation
<ol>
	<li>Consider the significance of the findings with respect to scrapie.</li>
	<li>Although the presence of individual signs, such as a repeatable response to scratching, tremor, abnormal behavior, circling, collapsing episodes, ataxia, or an absent menace response, may have various causes, the combined occurrence of two or more of these signs is highly suggestive of scrapie in sheep or goats.</li>
</ol>

<ol><li>Benestad, S. L., Arsac, J. N., Goldmann, W., Nöremark, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Atypical%2FNor98+scrapie%3A+properties+of+the+agent%2C+genetics%2C+and+epidemiology%5BTitle%5D)+AND+%22Vet+Res.%22%5BJournal%5D)">Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology.</a> Vet Res.. 39 (4), 19 (2008).</li>
<li>D'Angelo, A., Maurella, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assessment+of+clinical+criteria+to+diagnose+scrapie+in+Italy%5BTitle%5D)+AND+%22Vet.+J%22%5BJournal%5D)">Assessment of clinical criteria to diagnose scrapie in Italy.</a> Vet. J. 174 (1), 106-112 (2007).</li>
<li>Eloit, M., Adjou, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((BSE+agent+signatures+in+a+goat%5BTitle%5D)+AND+%22Vet.+Rec%22%5BJournal%5D)">BSE agent signatures in a goat.</a> Vet. Rec. 156 (16), 523-524 (2005).</li>
<li>Fediaevsky, A., Maurella, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+prevalence+of+atypical+scrapie+in+sheep+from+positive+flocks+is+not+higher+than+in+the+general+sheep+population+in+11+European+countries%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">The prevalence of atypical scrapie in sheep from positive flocks is not higher than in the general sheep population in 11 European countries.</a> BMC Vet. Res. 6, 9 (2010).</li>
<li>Healy, A. M., Weavers, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+clinical+neurology+of+scrapie+in+Irish+sheep%5BTitle%5D)+AND+%22J.+Vet.+Intern.+Med%22%5BJournal%5D)">The clinical neurology of scrapie in Irish sheep.</a> J. Vet. Intern. Med. 17 (6), 908-916 (2003).</li>
<li>Houston, E. F., Gravenor, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+signs+in+sheep+experimentally+infected+with+scrapie+and+BSE%5BTitle%5D)+AND+%22%22%5BJournal%5D)">Clinical signs in sheep experimentally infected with scrapie and BSE.</a> 152 (11), 333-334 (2003).</li>
<li>Kittelberger, R., Chaplin, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Atypical+scrapie%2FNor98+in+a+sheep+from+New+Zealand%5BTitle%5D)+AND+%22J.+Vet.+Diagn.+Invest%22%5BJournal%5D)">Atypical scrapie/Nor98 in a sheep from New Zealand.</a> J. Vet. Diagn. Invest. 22 (6), 863-875 (2010).</li>
<li>Konold, T., Bone, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Associations+of+clinical+signs+and+prion+protein+genotypes+in+British+sheep+with+scrapie%5BTitle%5D)+AND+%22Dtsch.+Tier%C3%A4rztl.+Wochenschr%22%5BJournal%5D)">Associations of clinical signs and prion protein genotypes in British sheep with scrapie.</a> Dtsch. Tierärztl. Wochenschr. 116 (11), 380-388 (2009).</li>
<li>Konold, T., Bone, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Scrapie+in+goats%5BTitle%5D)+AND+%22Vet.+Rec%22%5BJournal%5D)">Scrapie in goats.</a> Vet. Rec. 161 (11), 395-396 (2007).</li>
<li>Konold, T., Bone, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pruritus+is+a+common+feature+in+sheep+infected+with+the+BSE+agent%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">Pruritus is a common feature in sheep infected with the BSE agent.</a> BMC Vet. Res. 4, 16 (2008).</li>
<li>Konold, T., Bone, G. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Monitoring+of+clinical+signs+in+goats+with+transmissible+spongiform+encephalopathies%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">Monitoring of clinical signs in goats with transmissible spongiform encephalopathies.</a> BMC Vet. Res. 6, 13 (2010).</li>
<li>Konold, T., Davis, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+findings+in+two+cases+of+atypical+scrapie+in+sheep%3A+a+case+report%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">Clinical findings in two cases of atypical scrapie in sheep: a case report.</a> BMC Vet. Res. 3, 1 (2007).</li>
<li>Passler, T., Walz, P. H., Pugh, D. G. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aPassler%2C+T+%22Diseases+of+the+Neurologic+System.+In%3A+Sheep+and+Goat+Medicine%22">Diseases of the Neurologic System. In: Sheep and Goat Medicine</a>. Pugh, D. G., Baird, A. N. , 2, W.B.Saunders. Saint Louis. 361-405 (2012).</li>
<li>Russel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Body+condition+scoring+of+sheep%5BTitle%5D)+AND+%22In+Pract%22%5BJournal%5D)">Body condition scoring of sheep.</a> In Pract. 6 (3), 91-93 (1984).</li>
<li>Simmons, H. A., Simmons, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Atypical+scrapie+in+sheep+from+a+UK+research+flock+which+is+free+from+classical+scrapie%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">Atypical scrapie in sheep from a UK research flock which is free from classical scrapie.</a> BMC Vet. Res. 5, 8 (2009).</li>
<li>Simmons, M. M., Konold, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+natural+atypical+scrapie+phenotype+is+preserved+on+experimental+transmission+and+sub-passage+in+PRNP+homologous+sheep%5BTitle%5D)+AND+%22BMC+Vet.+Res%22%5BJournal%5D)">The natural atypical scrapie phenotype is preserved on experimental transmission and sub-passage in PRNP homologous sheep.</a> BMC Vet. Res. 6, 14 (2010).</li>
<li>Spiropoulos, J., Lockey, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Isolation+of+prion+with+BSE+properties+from+farmed+goat%5BTitle%5D)+AND+%22Emerg.+Infect.+Dis%22%5BJournal%5D)">Isolation of prion with BSE properties from farmed goat.</a> Emerg. Infect. Dis. 17 (12), 2253-2261 (2011).</li>
<li>Ulvund, M. J. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aUlvund%2C+MJ+%22Clinical+Findings+in+Scrapie.+In%3A+Prions+in+humans+and+animals%22">Clinical Findings in Scrapie. In: Prions in humans and animals</a>. Hörnlimann, B., Riesner, D., Kretzschmar, H. , de Gruyter. Berlin. 398-407 (2006).</li>
</ol>

All procedures involving animals were carried out in accordance with the Animal (Scientific Procedures) Act 1986, under license from the UK Government Home Office. 
The authors declare that they have no competing financial interests.

Scrapie is a listed disease by the World Health Organization for Animal Health (OIE), which, in the absence of a quick and reliable ante mortem test, relies on the farmers&#8217; or veterinarians&#8217; ability to recognize the clinical signs associated with this disease. Most scrapie cases, particularly atypical scrapie cases, however, are currently found by targeted TSE surveillance, i.e. by brain examination of small ruminants subject to slaughter or fallen stock animals. Breeding sheep for resistance to classical scrapie, which reduced the number of classical scrapie cases, most likely also reduced people&#8217;s awareness for the disease so that it is less often considered in the differential diagnosis of neurologic disorders in sheep. Atypical scrapie also has a low prevalence with approximately five cases in abattoirs and eight cases in fallen stock per 10,000 tested in Europe4. In addition, pruritus, usually evident as alopecia with or without excoriation, is often considered a characteristic sign of scrapie13. Thus, a neurologic disease without concomitant pruritus as observed in atypical scrapie12 or the nonpruritic form of caprine scrapie11 may not raise suspicion of scrapie.
This examination protocol was designed to identify clinical signs of TSE in sheep by evaluating specific clinical signs associated with various types of scrapie (atypical and classical scrapie, the latter represented by an atypical BSE-inoculated sheep, which presented with classical scrapie-like signs). In classical scrapie, the percentage of cases that displayed a positive scratch response (&#8220;nibble reflex&#8221;) ranged from 50-77 in over 100 sheep studied5,8. Movement disorders can be observed in up to 81% of classical scrapie cases based on various studies18. Incoordination is also a major sign in various naturally occurring cases of atypical scrapie, often accompanied by behavioral changes1, but additional signs reported in both naturally and experimentally infected atypical scrapie sheep were circling and visual impairment12,15,16, which is why blindfolding and the testing of the menace response is included in the examination protocol. Scoring the body condition, for example using a 6 point scoring system14, enables evaluation of emaciation, which may be observed in scrapie-affected sheep5. Although clinical criteria to aid in the detection of scrapie in sheep have been proposed previously2, these only related to the detection of classical scrapie and took the clinical history into account, which may not be available if animals are presented at an abattoir.
The current protocol allows screening of many animals for signs of scrapie within a short period of time. Furthermore, the examination protocol can be applied to experimental studies of scrapie in sheep and goats to monitor clinical onset, progression, and end-point. However, it does not replace a more detailed physical and neurologic examination with appropriate recording of the clinical case history, possibly followed by ancillary diagnostic tests (examination of blood and cerebrospinal fluid; more sophisticated imaging techniques if appropriate), which may be necessary subsequently to rule out various other conditions in small ruminants that present with similar signs, such as metabolic or inflammatory neurological diseases, brain abscesses, or tumors.
Although a clinical examination is generally less sensitive in detecting TSE-affected animals than post mortem tests based on detection of prion protein2,11, particularly in an early stage of the incubation period, this is currently the only detection method in live animals and most relevant to those countries that do not have a targeted surveillance system in place to identify TSE-affected small ruminants.

Scrapie is a transmissible spongiform encephalopathy (TSE) of sheep and goats, which belongs to the group of protein misfolding disorders, like bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease in deer, and Creutzfeldt-Jakob disease in humans. The diagnosis is made post mortem by detecting the abnormal form of the prion protein, which is proteinase-resistant, usually in the brain. Two major naturally occurring scrapie forms can be distinguished, which are epidemiologically, pathologically, and biochemically different: classical scrapie and atypical scrapie. In addition, a neurological disease with classical scrapie-like clinical signs can be induced in sheep and goats by experimental infection with the BSE agent6,10-11. In fact, naturally occurring BSE has been diagnosed in goats3,17. Control of classical scrapie (and BSE in sheep if it occurred naturally) has been achieved by breeding for genetic resistance targeting the prion protein gene, but this is more difficult for atypical scrapie, which is believed to be a sporadic disease and has been diagnosed in countries considered to be free from classical scrapie, e.g. New Zealand7.
Scrapie is a neurologic disease of adult sheep and goats resulting in changes in behavior, sensation, and movement, but the disease is slowly progressive, and clinical signs are often not recognized because the animal keeper or veterinary surgeon may not be familiar with the clinical signs, or scrapie is not considered at all in the differential diagnosis of neurologic diseases in small ruminants.
The proposed examination protocol was designed to aid in the clinical diagnosis of scrapie with two purposes in mind: it should be considerably brief to allow scanning of many animals within a short period of time but specific enough to allow detection of scrapie-affected animals, which is achieved by assessing the presence of clinical signs frequently encountered in scrapie-affected animals. This protocol is a slight modification from the one used to monitor goats for signs of classical scrapie11 and includes blindfolding of the animal, which may exacerbate clinical signs not normally associated with scrapie9.

clinical examination protocol to detect atypical and classical scrapie in sheep

Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep

The diagnosis of scrapie, a transmissible spongiform encephalopathy (TSEs) of sheep and goats, is currently based on the detection of disease-associated prion protein by post mortem tests. Unless a random sample of the sheep or goat population is actively monitored for scrapie, identification of scrapie cases relies on the reporting of clinical suspects, which is dependent on the individual&#39;s familiarization with the disease and ability to recognize clinical signs associated with scrapie. Scrapie may not be considered in the differential diagnosis of neurological diseases in small ruminants, particularly in countries with low scrapie prevalence, or not recognized&#160;if it presents as nonpruritic form like atypical scrapie. To aid in the identification of clinical suspects, a short examination protocol is presented to assess the display of specific clinical signs associated with pruritic and nonpruritic forms of TSEs in sheep, which could also be applied to goats. This includes assessment of behavior, vision (by testing of the menace response), pruritus (by testing the response to scratching), and movement (with and without blindfolding). This may lead to a more detailed neurologic examination&#160;of reporting animals as scrapie suspects. It&#160;could also be used in experimental TSE studies of sheep or goats to evaluate disease progression or to identify clinical end-point.

Clinically healthy sheep. Poll Dorset wether from a scrapie-free flock intracerebrally inoculated with bovine brain of New Zealand origin and examined at 49 months post inoculation. This sheep has a normal posture, behaves normally, displays a normal menace response (Figure 1), does not react to the scratch test, has an intact fleece, and a very good body condition. It is clinically unremarkable when blindfolded and shows no signs of a movement disorder.
Atypical scrapie sheep presenting with the nonpruritic form of TSEs in sheep. Cheviot wether from a scrapie-free flock intracerebrally inoculated with brain homogenate from an atypical scrapie field case of the same prion protein genotype (AHQ/AHQ) and examined at 36 months post inoculation. This sheep also has a normal posture but behaves differently to the other sheep in the pen and circles in clockwise direction. It does not blink when the menace response is tested. Scratching does not elicit any response, and no fleece changes are apparent, but the body condition is only fair. It circles clockwise when blindfolded (Figure 2) and loses balance. The gait is ataxic, and a fine head tremor is visible.
Atypical BSE sheep presenting with the pruritic form of TSEs in sheep, which is clinically similar to the clinical presentation of classical scrapie-affected sheep. For this reason, a classical scrapie case is not included. Poll Dorset wether from a scrapie-free flock intracerebrally inoculated with bovine atypical (L-type) BSE brain homogenate and examined at 50 months post inoculation. This sheep stands slightly hunched, tends to keep the hind limbs wide-based and falls on the floor when caught. The menace response is weak. Scratching of various areas of the back elicits head or lip movements (Figure 3), and there is wool loss with minor skin trauma on the poll. The body condition is good. When blindfolded, it is reluctant to move and rests its rear end on the hurdle to maintain balance. The sheep is ataxic and displays fore limb hypermetria.
<img alt="Sheep handling in genetic research procedure, with tagged animal and gloved researcher in lab coats." fo:content-width="5in" fo:src="/files/ftp_upload/51101/51101fig1highres.jpg" src="/files/ftp_upload/51101/51101fig1.jpg" data-altupdatedat="1787630408000" data-alt="Figure 1"> 
Figure 1. Menace response testing. Menacing gesture towards the animal’s eye induces a blink response. <a href="https://www.jove.com/files/ftp_upload/51101/51101fig1highres.jpg" target="_blank">Click here to view larger image.</a>
<img alt="Sheep behavior study; animal in controlled environment; observational research; data collection." fo:content-width="5in" fo:src="/files/ftp_upload/51101/51101fig2highres.jpg" src="/files/ftp_upload/51101/51101fig2.jpg" data-altupdatedat="1787630408000" data-alt="Figure 2"> 
Figure 2. Blindfolding. Clockwise circling elicited by blindfolding the sheep with a hood. <a href="https://www.jove.com/files/ftp_upload/51101/51101fig2highres.jpg" target="_blank">Click here to view larger image.</a>
<img alt="Sheep handling process, farm management technique, animal husbandry, livestock care demonstration." fo:content-width="5in" fo:src="/files/ftp_upload/51101/51101fig3highres.jpg" src="/files/ftp_upload/51101/51101fig3.jpg" data-altupdatedat="1787630408000" data-alt="Figure 3"> 
Figure 3. Testing of the scratch response. Scratching of the back elicits lip licking with sideward movements of the head <a href="https://www.jove.com/files/ftp_upload/51101/51101fig3highres.jpg" target="_blank">Click here to view larger image.</a>

A short clinical examination protocol is presented to aid in the detection of classical and atypical scrapie in sheep and goats.

The diagnosis of scrapie, a transmissible spongiform encephalopathy (TSEs) of sheep and goats, is currently based on the detection of disease-associated ...

Scrape is a transmissible Spongiform encephalopathy in sheep and goats, which causes neurological signs in affected animals. Confirmation of disease is made post-mortem on examination of the brain, which also allows classification into different forms of scrape, classical, scrape, atypical scrape, and rarely other forms transmitted from other species such as bovine fungi form encephalopathy. Abbreviated BSE Scrape is a listed disease by the World Health Organization for Animal Health, but the disease is often not recognized and affected small ruminants.This video demonstrates a short clinical examination protocol lasting approximately five minutes to aid in the detection of clinical cases affected by transmissible, spongy form and encephalopathies using three sheep as examples. Example one is A clinically healthy sheep cerebrally inoculated with BSC. Free bovine brain homogenate examined at 49 months post inoculation, which represents a control.Example two is a clinically affected sheep interest cerebrally inoculated with atypical scrapy OV brain homogenate examined at 36 months post inoculation, which represents an atypical scrapy case. Example three is a clinically affected sheep interest re inoculate with atypical BSE bovine brain Homogenate examined at 50 months post inoculation, which presents clinically similar to classical scrapy. For this reason, a classical scrapy case is not included.Assessment or posture. The healthy sheep carrying the ear tag number one and indicated by the red arrow displays a normal posture when undisturbed in the pen. The posture of the atypical scrapy sheep also appears normal.The sheep with atypical BSC appears slightly hunched and tends to sound with its hind limbs. Wide based assessment of behavior as expected in normal sheep, the healthy sheep stays within the group and follows the movements of the examiner. With its size approaching and catching the sheep does not elicit any abnormality.The atypical scrapy sheep behaves differently to the other sheep in the pen and stands with its rear towards the camera, whereas all other sheep look towards the camera. Sheep are social animals are moving groups, but this sheep does immediately follow other sheep and appears to be slow in realizing that the other sheep are gone clockwise. Circling is elicited after examination of this sheet.This compulsive behavior only stops when the sheep is approached and it runs away. The sheep with atypical BSC falls on the floor when handled after being caught. Menace response testing, moving the hand or several fingers several times towards each eye of the animal without touching any facial hairs or creating any air.Turbulence should elicit blinking as seen for both eyes and the healthy sheep. The men's response is lost in the sheep with atypical scrapy, which does not blink. Although its ability to blink when the eyelids are touched is not impaired.The atypical BSE sheet blinks in response to the menace, but the blink response is weak in the left eye compared to the blink response. When the eyelid is touched, Testing of the scratch response, the tests are here performed whilst the sheep stands next to a wall, and this is prevented from escaping forward by one leg of the examiner, the sheep is calm enough to continue with the test. Several areas of the back are scratched here, the sacral lumbar tho columbar, mid-thoracic, and cranial thoracic regions with a pause between each scratching episode to observe the response.This clinically healthy sheep does not show a repeatable stereotypical response. Similarly, the sheep with atypical scrapy does not respond to scratching of several areas of the back. A response, however, is elicited when the sheep with atypical BSC is scratched.Depending on the area that is scratched, is either reacts with nibbling movements of the lip or head movements. This response is considered Positive Checking for wall loss and skin lesions. Extensive areas of wall loss with or without skin lesions can usually be observed from a distance, but closer examination of the sheep during restraint may identify smaller areas of wall loss caused by excessive pruritus.These areas are often found on the head, back, rum and side of thorax or abdomen, often bilateral symmetrical. While no wall loss is detected in the control sheep and the sheep with atypical scrapy, the sheep with atypical BSC has lost its wool on the pole. The skin is otherwise intact except for a small scab that has formed after damage of the skin.This may have been caused by excessive pruritus scoring body condition. The animal's body condition is scored by feeling the transverse and dorsal processes of the lumbar. This can also be done during the scratch testing of the sheep.A score from nought to five may be used with five being assigned to a very obese sheep. This is represented in the drawn image of a cross section through the lumbar vertebral column. The processes of the vertebrae are covered by muscle in red and fat tissue in yellow, and it would be impossible to fill the ends of the transverse processes even if you applied pressure to the skin.By contrast, the body condition is poor. If the ends of the spinal processes feel sharp, that applying any pressure and no overlaying factor sheet can be felt as demonstrated in this image. This would be scored as naught.The body condition is very good in the clinically healthy sheep with a score of four atypical scrapie caused a loss in bodily condition, which is only fair with a score of two. Whereas the sheep with atypical BSC has maintained a good body condition score of three blindfolding. The animal, the sheep's head is covered here with a handmade blindfold, which could be any non C3 bag where one corner is cut off the animal's nose to allow breathing before releasing the sheep, make sure it is safe for the animal to do so.Some sheep may panic and run or jump around and may be in danger of hurting themselves or others. In this case, do not release the sheep completely and study animal movements while still holding the animal. The healthy sheep remains calm and blindfolded, but tosses its head in an attempt to remove the blindfold.Its movement or balance is not impaired. In contrast, the sheep with atypical scrapie starts circling in clockwise direction. There is also loss of balance.The sheep with atypical BSC is reluctant to move and leans against the hurdle, but whilst doing so, it cross its four legs and loss of balance is evident. Assessment of the animal's movement, the gait in the clinically healthy sheep appears normal. There is no obvious tremor, neither when the sheep is left undisturbed nor earlier during handling.Ataxia is present in the sheep with atypical scrapie. It slips when it follows the other sheep and its hind limb movements appear. Incoordinated a fine head tremor can be observed briefly when the sheep stands in the group.A texture is also apparent in the sheep notated with atypical BSE. There is a loss of balance in coordination and hyper metra as can be seen by the high stepping fall. Gait interpretation.Clinical signs shown in those sheep affected by transmissible spongy form, encephalopathies included abnormal behavior, an absent menace response, a positive scratch response alopecia, skin damage circling when blindfolded in coordination and tremor, the display of one or in the case is presented here. More of any of these signs should alert the examiner and scrape should be considered as one of the causes.Conclusion. This video shows the clinical examination protocol performed on a clinically healthy sheep and gives examples of abnormal findings in sheep affected by transmissible spongiform encephalopathies.This protocol is useful to detect clinically suspicious cases which may be examined in more detail to rule out other diseases with a similar clinical presentation or may be used to assess clinical onset disease progression or clinical endpoints. In experimental studies of transmissible spongy form encephalopathies in small ruminants.

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Research

JoVE Journal

Medicine

Scavengers have potential to translocate infectious transmissible spongiform encephalopathy prions in their feces to disease-free areas.  We detail methods used to determine if mouse-adapted scrapie prions remain infectious after passage though the digestive tract of American crows (Corvus brachyrhynchos), a common consumer of dead animals.

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Measuring the barrier to the interspecies transmission of prion diseases is challenging and typically involves animal challenges or biochemical assays. Here, we present an in vitro prion protein conversion assay with the ability to predict species barriers.

Assessing Transmissible Spongiform Encephalopathy Species Barriers with an In Vitro Prion Protein Conversion Assay

Here, we present a protocol to describe a simple, fast and efficient prion amplification technique, the real-time quaking-induced conversion (RT-QuIC) method.

Real-time Quaking-induced Conversion Assay for Detection of CWD Prions in Fecal Material

The direct rapid immunohistochemical test (DRIT) offers a World Organization for Animal Health and World Health Organization (OIE/WHO) recognized alternative to the direct fluorescent antibody (DFA) test for rabies diagnosis. This test allows for field-based applications that can be performed in approximately 1 h upon brain impressions using light microscopy.

Enhanced Rabies Surveillance Using a Direct Rapid Immunohistochemical Test

The goal of this protocol is to demonstrate safe necropsy techniques in small and large animals to obtain satisfactory tissue samples for rabies testing.

Rabies Necropsy Techniques in Large and Small Animals

We present a complete protocol for postmortem diagnosis of animal rabies under field conditions using a rapid immunochromatographic diagnostic test (RIDT), from brain biopsy sampling to final interpretation. We also describe further applications using the device for molecular analysis and viral genotyping.

Field Postmortem Rabies Rapid Immunochromatographic Diagnostic Test for Resource-Limited Settings with Further Molecular Applications

Immunolabeling abnormal prion protein using immunohistochemistry protocols requires specific sample and anti-PrP antibody preparation methodologies. The present protocol describes the key steps in epitope demasking to ensure proper PrP immunolabeling and to minimize non-specific background staining. Also, this approach considers biosafety measures when conducting immunohistochemistry studies with the prion-infected tissues.

Detection of Abnormal Prion Protein by Immunohistochemistry

Experimental autoimmune encephalomyelitis is one of the most widely used murine models of multiple sclerosis. In the current protocol, C57BL/6J mice of both sexes are immunized with myelin oligodendrocyte glycoprotein peptide, resulting mainly in ascending paresis of the tail and limbs. Here we discuss the protocol of EAE induction and evaluation.

Modeling Multiple Sclerosis in the Two Sexes: MOG35-55-Induced Experimental Autoimmune Encephalomyelitis

This protocol demonstrates the pan-lyssavirus LN34 real-time reverse transcription-polymerase chain reaction (RT-PCR) assay from tissue collection to result interpretation, including updates to primer sequences and formulations to improve assay performance for some non-rabies lyssaviruses and lagomorphs. We also demonstrate the assay setup for a single-well LN34 multiplexed (LN34M) format.

Postmortem Diagnosis of Rabies in Animals by the Updated, Multiplexed LN34 Real-Time Reverse Transcription-Polymerase Chain Reaction Assay

A method to assess commonly used areas in laboratory settings for prion contamination and effective decontamination is lacking. The protocol described here provides key fundamentals for implementing a laboratory prion safety swipe test that can easily be modified to meet the individual needs of specific laboratories.

Prion Safety Laboratory Swipe Test

Learn a five-minute clinical examination protocol to detect classical and atypical scrapie in sheep and goats. This method helps veterinarians identify neurological signs and improve early disease detection.

Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep

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