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Intervertebral Disc Disease in African Hedgehogs (Atelerix albiventris): Four Cases
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Intervertebral Disc Disease in African Hedgehogs (Atelerix albiventris): Four Cases James T. Raymond, MS, DVM, Dip. ACVP, Roberto Aguilar, DVM, Freeland Dunker, DVM, John Ochsenreiter, DVM, Sally Nofs, DVM, Wynona Shellabarger, DVM, and Michael M. Garner, DVM, Dip. ACVP
Abstract Four, adult, captive, African hedgehogs (Atelerix albiventris) were diagnosed with intervertebral disc disease. Clinical signs associated with intervertebral disc disease were progressive hindlimb ataxia, urinary stasis, loss of proprioception, and lameness. Radiographs on 2 of the cases revealed narrowing of the cervical intervertebral spaces and spondylosis. Histologically, all hedgehogs had several intervertebral discs that were degenerative and protruded dorsally into the vertebral canal, which, in some cases, caused compressive damage to the spinal cord. The clinical signs exhibited by the animals described in this report were similar to the signs of wobbly hedgehog syndrome. Based on this case series, clinical evaluation for disc disease is recommended in hedgehogs with signs of ambulatory dysfunction. Copyright 2009 Elsevier Inc. All rights reserved. Key words: ataxia; Atelerix albiventris; degenerative; hedgehog; intervertebral disc disease
A
frican hedgehogs (Atelerix albiventris) are a popular exotic pet, as well as a small mammal commonly exhibited by many zoological parks. Diseases such as neoplasia, chronic interstitial nephritis, and cardiomyopathy are commonly diagnosed in captive, adult hedgehogs.1-3 Recently, a neurologic condition of unknown cause referred to as wobbly hedgehog syndrome (WHS) has been noted in captive hedgehogs.4,5 We report herein the first cases of intervertebral disc disease (IVD) in hedgehogs, which, in some instances, clinically resembles WHS.
Case Reports Case 1 involved a 6.5-year-old male hedgehog housed at a Northern Californian zoological park that devel-
220
oped peripheral vestibular disease characterized by ataxia that initially responded to supportive care and corticosteroids for several months after presentation of the problem. Radiographs revealed narrowing of C2-C3 and C3-C4 intervertebral spaces and spondy-
From the Northwest ZooPath, Snohomish, WA USA; the Audubon Zoo, The Audubon Nature Institute, New Orleans, LA USA; the San Francisco Zoo, San Francisco, CA USA; and The Toledo Zoo, Toledo, OH USA. Address correspondence to: Michael M. Garner, DVM, Dip. ACVP, Northwest ZooPath, 654 West Main, Monroe, WA 98296. E-mail: [email protected]. © 2009 Elsevier Inc. All rights reserved. 1557-5063/09/1803-$30.00 doi:10.1053/j.jepm.2009.06.007
Journal of Exotic Pet Medicine, Vol 18, No 3 ( July), 2009: pp 220-223
Intervertebral Disc Disease in African Hedgehogs
Figure 1. Hedgehog, case 1. Radiographic image showing focus of intervertebral disc disease in cervical vertebral column. Note narrowing of disc spaces at C2 to C3 and C3 to C4 (arrows) and spondylosis.
losis between C2 and C3 (Fig 1). In April 2001, the hedgehog had another episode of neurologic disease that was unresponsive to treatment and 2 months later was humanely euthanized. At necropsy, the lungs were congested and the liver was pale with increased firmness. The kidneys had cortical infarcts, and the hedgehog’s adrenal glands were enlarged. Case 2 was a 4-year-old female hedgehog from the same Northern Californian zoological park that developed lameness in the left front limb. Radiographs revealed spondylosis between C2 and C3 and C4 and C5 and narrowing of C4-C5 intervertebral space with increased radiodensity (mineralization) of the intervertebral disc. For humane reasons, the hedgehog was euthanized. At necropsy, the hedgehog was in good body condition, had slightly enlarged kidneys, pinpoint consolidation of the left caudal lung, and a 3-cm mass infiltrating the dorsocervical and retroscapular soft tissues. Case 3 was a male, approximately 4-year-old hedgehog from a zoological park in the southeastern United States that had a prolonged history of urinary bladder atony with urinary stasis and progressive bilateral hindlimb ataxia with loss of proprioception. Euthanasia was performed for humane and diagnostic purposes. At necropsy, there was severe distention of the urinary bladder and a 1-cm area of dark discoloration on the spleen. Longitudinal sections of the lumbar spine revealed expansion of adjacent intervertebral joints associated with thickening and white
221 discoloration of the intervertebral discs. Affected discs were partially prolapsed into the spinal canal, and the adjacent spinal cord was dorsally displaced and slightly compressed (Fig 2). Case 4 was an approximately 6-year-old male hedgehog from a zoological park in the Midwestern United States that was humanely euthanized because of infiltrative, oral squamous cell carcinoma. At necropsy, there was a segment of cervical spine that had two small, hard, 0.5-mm ventral protrusions interpreted as spondylosis. Tissues from the 4 hedgehogs were submitted to Northwest ZooPath fixed in 10% neutral buffered formalin. Northwest ZooPath subsequently decalcified the bone, which, along with other tissue samples, were embedded in paraffin, sectioned the tissues at 5.0 m, and then stained them with hematoxylin and eosin. Histologically, all hedgehogs described in this report had multiple intervertebral disc degeneration of the nucleus pulposus and annulus fibrosus, fissures and neovascularization in the annulus fibrosus, and mild to moderate, dorsal extrusion of the annulus fibrosus and nucleus pulposus into the spinal canal. Some of the intervertebral discs were incompletely protruded and still covered by thin layers of annulus fibrosus. Some of the completely protruding intervertebral discs had replacement of the mucinous nucleus pulposus by irregularly mineralized and fragmented cartilaginous tissue. In cases 1 to 3, the cervical vertebrae were primarily affected. In addition, case 4 had similar degenerative disc lesions in the lumbar vertebral column (Fig 3). Three hedgehogs had ventral bridging osteophytes (spondylosis) between cervical vertebrae with degenerate intervertebral discs. In all cases, there was mild to moderate multifocal compression of the spinal cord by the dorsally protruding disc material. The compressed
Figure 2. Hedgehog, case 3. Note thickening and calcification of intervertebral discs in the lumbar spinal column (arrows), with partial disc proptosis and associated compression of the spinal cord (arrowhead).
222
Figure 3. Hedgehog, case 4. Tangentially sectioned lumbar spinal column. Note complete degeneration of lumbar intervertebral disc, thickening of the joint space (j), and nodular cartilaginous material above the joint (arrows) that extends into the vertebral canal. The spinal cord (c) has some vacuolar change corresponding to axonal degeneration. The adjacent intervertebral disc (d) is normal. Hematoxylin and eosin (bar) ⫽ 300 m.
spinal cord had multifocal axonal swelling, edema, and digestion chambers (Fig 4), and these lesions were more severe in the lateral and ventral funiculi. Case 2 had several spinal nerve roots that had degenerate and swollen axons. Case 1 also had a fibrocartilaginous embolus within a longitudinal venous sinus.
Discussion Intervertebral disc disease is a progressive debilitating condition that involves the degeneration of one or more intervertebral discs. Ultimately, there is dorsal protrusion of the damaged discs that results in compressive damage to the spinal cord. The disease usually manifests by progressive neurologic signs including loss of proprioception, ataxia, paresis, and, in some cases, paralysis. Hindlimb ataxia with progression to paresis and paralysis, as noted in case 3, is a common clinical sign in dogs with IVD.6 Also, the urinary bladder atony in case 3 was likely due to compressive damage to spinal nerve roots from herniated disc material in the lumbosacral region. Neurogenic distension of the urinary bladder is a common sequela to lumbar disc herniation in dogs. The forelimb lameness in hedgehog 2 was from compression of cervical spinal nerve roots by the prolapsed intervertebral disc. The vestibular signs (e.g., ataxia) in case 1 can be attributed in part to the spinal cord damage from the histologically observed protruding cervical intervertebral discs. The clinical signs exhib-
Raymond et al
ited by these hedgehogs with IVD were directly related to the compressive damage to the spinal cord and spinal nerve roots by the herniated disc material. Although myelography is the diagnostic technique of choice for IVD, standard radiographs of the vertebral column helped make a clinical diagnosis of IVD in cases 1 and 2. Spinal radiographs made for evaluation of IVD in hedgehogs should include lateral views of the cervical and lumbar regions. Fortunately, hedgehogs are small enough that the entire spine can be visualized on one lateral radiographic view. Radiographs were not available for cases 3 and 4. Intervertebral disc disease in the hedgehogs described in this report had histologic features of chondrodystrophic breed–associated disc disease in canids. In all of the hedgehogs, there was replacement of the mucinous component of the nucleus pulposus with cartilage-like tissue that eventually became mineralized. This is a characteristic lesion described in chondrodystrophic dogs with IVD.7 Spondylosis, as noted in 3 hedgehogs, develops in ongoing cases of IVD because of the creation of abnormal movement between vertebrae from degeneration of the annulus fibrosis and from inflammation with bone proliferation elicited by ventrally protruding disc material. Case 1 had fibrocartilaginous embolus, which has been noted in large-breed dogs with herniated fragments of nucleus pulposus. Recently, there has been an emergence of a condition in captive African hedgehogs referred to as wobbly hedgehog syndrome (WHS).4,5 This condition mainly affects hedgehogs ⬍2 years of age. The main clinical sign of WHS is progressive ataxia orig-
Figure 4. Hedgehog, case 4. Higher magnification of spinal cord in Figure 3. Note vacuolar change likely reflecting axonal edema (arrows), and a vacuole containing cellular debris (arrowhead). Hematoxylin and eosin (bar) ⫽ 120 m.
223
Intervertebral Disc Disease in African Hedgehogs
inating in the rear limbs. Histologically, there is demyelination primarily within the spinal cord. The underlying etiology for WHS is still unknown at the present time. Early clinical signs of hedgehogs with WHS are very similar to the clinical signs exhibited by the hedgehogs with IVD. It may be difficult to clinically differentiate IVD from early stages of WHS without the aid of radiographs or postmortem examination of the spinal column. One difference in the clinical presentation between hedgehogs with IVD and hedgehogs with WHS is that hedgehogs with IVD were typically older at the time of presentation than hedgehogs with WHS. A paralytic condition associated with demyelination in the central nervous system has also been reported in European hedgehogs (Erinaceus europaeus).8 The cause for this neurologic disease has not been determined at this time. The clinical signs of this disease are very similar to those noted in the hedgehogs with IVD and those described for hedgehogs with WHS. The primary difference in the European hedgehog demyelinating disease is the histologic presence of inflammation within the central nervous system, a feature neither noted in our hedgehogs with IVD nor in African hedgehogs with WHS. The purpose of this report was to present 4 cases of IVD in hedgehogs. Given the close similarities of the clinical signs of IVD and WHS in African hedgehogs, diagnostic imaging is recommended for all hedgehogs with progressive neurologic disease to screen for evidence of IVD. Histologic examination of the spinal column is helpful for detection of IVD and associated lesions in the spinal cord.
Acknowledgments We thank R. Brown at Histology Consulting Service for expertise in slide preparation, Jamie Kinion of Northwest ZooPath for data retrieval, and Christie Buie of Northwest ZooPath for photo editing and manuscript submission.
References 1.
2.
3.
4.
5. 6. 7.
8.
Raymond JT, White MR: Necropsy and histopathologic findings in 14 African hedgehogs (Atelerix albiventris): a retrospective study. J Zoo Wildl Med 30:273277, 1999 Raymond JT, Garner MM: Cardiomyopathy in captive African hedgehogs (Atelerix albiventris). J Vet Diagn Invest 12:468-472, 2000 Raymond JT, Garner MM: Spontaneous tumours in captive African hedgehogs (Atelerix albiventris): a retrospective study. J Comp Pathol 124:128-133, 2001 Graesser D, Spraker TR, Dressen P, et al: Wobbly hedgehog syndrome in African pygmy hedgehogs (Atelerix sp.). J Exotic Pet Med 15:59-65, 2006 Garner MM, Graesser D: Wobbly hedgehog syndrome. Exotic DVM 8:27-29, 2006 Simpson ST: Intervertebral disc disease. Vet Clin North Am Small Anim Pract 22:889-897, 1992 Palmer N: Bones and joints, in Jubb KV F, Kennedy PC, Palmer N (eds): Pathology of Domestic Animals (ed 4). San Diego, CA, Academic Press, Inc., pp 153158, 1993 Palmer AC, Blakemore WF, Franklin RJM, et al: Paralysis in hedgehogs (Erinaceus europaeus) associated with demyelination. Vet Rec 143:550-552, 1998
Intervertebral Disc Disease in African Hedgehogs (Atelerix albiventris): Four Cases James T. Raymond, MS, DVM, Dip. ACVP, Roberto Aguilar, DVM, Freeland Dunker, DVM, John Ochsenreiter, DVM, Sally Nofs, DVM, Wynona Shellabarger, DVM, and Michael M. Garner, DVM, Dip. ACVP
Abstract Four, adult, captive, African hedgehogs (Atelerix albiventris) were diagnosed with intervertebral disc disease. Clinical signs associated with intervertebral disc disease were progressive hindlimb ataxia, urinary stasis, loss of proprioception, and lameness. Radiographs on 2 of the cases revealed narrowing of the cervical intervertebral spaces and spondylosis. Histologically, all hedgehogs had several intervertebral discs that were degenerative and protruded dorsally into the vertebral canal, which, in some cases, caused compressive damage to the spinal cord. The clinical signs exhibited by the animals described in this report were similar to the signs of wobbly hedgehog syndrome. Based on this case series, clinical evaluation for disc disease is recommended in hedgehogs with signs of ambulatory dysfunction. Copyright 2009 Elsevier Inc. All rights reserved. Key words: ataxia; Atelerix albiventris; degenerative; hedgehog; intervertebral disc disease
A
frican hedgehogs (Atelerix albiventris) are a popular exotic pet, as well as a small mammal commonly exhibited by many zoological parks. Diseases such as neoplasia, chronic interstitial nephritis, and cardiomyopathy are commonly diagnosed in captive, adult hedgehogs.1-3 Recently, a neurologic condition of unknown cause referred to as wobbly hedgehog syndrome (WHS) has been noted in captive hedgehogs.4,5 We report herein the first cases of intervertebral disc disease (IVD) in hedgehogs, which, in some instances, clinically resembles WHS.
Case Reports Case 1 involved a 6.5-year-old male hedgehog housed at a Northern Californian zoological park that devel-
220
oped peripheral vestibular disease characterized by ataxia that initially responded to supportive care and corticosteroids for several months after presentation of the problem. Radiographs revealed narrowing of C2-C3 and C3-C4 intervertebral spaces and spondy-
From the Northwest ZooPath, Snohomish, WA USA; the Audubon Zoo, The Audubon Nature Institute, New Orleans, LA USA; the San Francisco Zoo, San Francisco, CA USA; and The Toledo Zoo, Toledo, OH USA. Address correspondence to: Michael M. Garner, DVM, Dip. ACVP, Northwest ZooPath, 654 West Main, Monroe, WA 98296. E-mail: [email protected]. © 2009 Elsevier Inc. All rights reserved. 1557-5063/09/1803-$30.00 doi:10.1053/j.jepm.2009.06.007
Journal of Exotic Pet Medicine, Vol 18, No 3 ( July), 2009: pp 220-223
Intervertebral Disc Disease in African Hedgehogs
Figure 1. Hedgehog, case 1. Radiographic image showing focus of intervertebral disc disease in cervical vertebral column. Note narrowing of disc spaces at C2 to C3 and C3 to C4 (arrows) and spondylosis.
losis between C2 and C3 (Fig 1). In April 2001, the hedgehog had another episode of neurologic disease that was unresponsive to treatment and 2 months later was humanely euthanized. At necropsy, the lungs were congested and the liver was pale with increased firmness. The kidneys had cortical infarcts, and the hedgehog’s adrenal glands were enlarged. Case 2 was a 4-year-old female hedgehog from the same Northern Californian zoological park that developed lameness in the left front limb. Radiographs revealed spondylosis between C2 and C3 and C4 and C5 and narrowing of C4-C5 intervertebral space with increased radiodensity (mineralization) of the intervertebral disc. For humane reasons, the hedgehog was euthanized. At necropsy, the hedgehog was in good body condition, had slightly enlarged kidneys, pinpoint consolidation of the left caudal lung, and a 3-cm mass infiltrating the dorsocervical and retroscapular soft tissues. Case 3 was a male, approximately 4-year-old hedgehog from a zoological park in the southeastern United States that had a prolonged history of urinary bladder atony with urinary stasis and progressive bilateral hindlimb ataxia with loss of proprioception. Euthanasia was performed for humane and diagnostic purposes. At necropsy, there was severe distention of the urinary bladder and a 1-cm area of dark discoloration on the spleen. Longitudinal sections of the lumbar spine revealed expansion of adjacent intervertebral joints associated with thickening and white
221 discoloration of the intervertebral discs. Affected discs were partially prolapsed into the spinal canal, and the adjacent spinal cord was dorsally displaced and slightly compressed (Fig 2). Case 4 was an approximately 6-year-old male hedgehog from a zoological park in the Midwestern United States that was humanely euthanized because of infiltrative, oral squamous cell carcinoma. At necropsy, there was a segment of cervical spine that had two small, hard, 0.5-mm ventral protrusions interpreted as spondylosis. Tissues from the 4 hedgehogs were submitted to Northwest ZooPath fixed in 10% neutral buffered formalin. Northwest ZooPath subsequently decalcified the bone, which, along with other tissue samples, were embedded in paraffin, sectioned the tissues at 5.0 m, and then stained them with hematoxylin and eosin. Histologically, all hedgehogs described in this report had multiple intervertebral disc degeneration of the nucleus pulposus and annulus fibrosus, fissures and neovascularization in the annulus fibrosus, and mild to moderate, dorsal extrusion of the annulus fibrosus and nucleus pulposus into the spinal canal. Some of the intervertebral discs were incompletely protruded and still covered by thin layers of annulus fibrosus. Some of the completely protruding intervertebral discs had replacement of the mucinous nucleus pulposus by irregularly mineralized and fragmented cartilaginous tissue. In cases 1 to 3, the cervical vertebrae were primarily affected. In addition, case 4 had similar degenerative disc lesions in the lumbar vertebral column (Fig 3). Three hedgehogs had ventral bridging osteophytes (spondylosis) between cervical vertebrae with degenerate intervertebral discs. In all cases, there was mild to moderate multifocal compression of the spinal cord by the dorsally protruding disc material. The compressed
Figure 2. Hedgehog, case 3. Note thickening and calcification of intervertebral discs in the lumbar spinal column (arrows), with partial disc proptosis and associated compression of the spinal cord (arrowhead).
222
Figure 3. Hedgehog, case 4. Tangentially sectioned lumbar spinal column. Note complete degeneration of lumbar intervertebral disc, thickening of the joint space (j), and nodular cartilaginous material above the joint (arrows) that extends into the vertebral canal. The spinal cord (c) has some vacuolar change corresponding to axonal degeneration. The adjacent intervertebral disc (d) is normal. Hematoxylin and eosin (bar) ⫽ 300 m.
spinal cord had multifocal axonal swelling, edema, and digestion chambers (Fig 4), and these lesions were more severe in the lateral and ventral funiculi. Case 2 had several spinal nerve roots that had degenerate and swollen axons. Case 1 also had a fibrocartilaginous embolus within a longitudinal venous sinus.
Discussion Intervertebral disc disease is a progressive debilitating condition that involves the degeneration of one or more intervertebral discs. Ultimately, there is dorsal protrusion of the damaged discs that results in compressive damage to the spinal cord. The disease usually manifests by progressive neurologic signs including loss of proprioception, ataxia, paresis, and, in some cases, paralysis. Hindlimb ataxia with progression to paresis and paralysis, as noted in case 3, is a common clinical sign in dogs with IVD.6 Also, the urinary bladder atony in case 3 was likely due to compressive damage to spinal nerve roots from herniated disc material in the lumbosacral region. Neurogenic distension of the urinary bladder is a common sequela to lumbar disc herniation in dogs. The forelimb lameness in hedgehog 2 was from compression of cervical spinal nerve roots by the prolapsed intervertebral disc. The vestibular signs (e.g., ataxia) in case 1 can be attributed in part to the spinal cord damage from the histologically observed protruding cervical intervertebral discs. The clinical signs exhib-
Raymond et al
ited by these hedgehogs with IVD were directly related to the compressive damage to the spinal cord and spinal nerve roots by the herniated disc material. Although myelography is the diagnostic technique of choice for IVD, standard radiographs of the vertebral column helped make a clinical diagnosis of IVD in cases 1 and 2. Spinal radiographs made for evaluation of IVD in hedgehogs should include lateral views of the cervical and lumbar regions. Fortunately, hedgehogs are small enough that the entire spine can be visualized on one lateral radiographic view. Radiographs were not available for cases 3 and 4. Intervertebral disc disease in the hedgehogs described in this report had histologic features of chondrodystrophic breed–associated disc disease in canids. In all of the hedgehogs, there was replacement of the mucinous component of the nucleus pulposus with cartilage-like tissue that eventually became mineralized. This is a characteristic lesion described in chondrodystrophic dogs with IVD.7 Spondylosis, as noted in 3 hedgehogs, develops in ongoing cases of IVD because of the creation of abnormal movement between vertebrae from degeneration of the annulus fibrosis and from inflammation with bone proliferation elicited by ventrally protruding disc material. Case 1 had fibrocartilaginous embolus, which has been noted in large-breed dogs with herniated fragments of nucleus pulposus. Recently, there has been an emergence of a condition in captive African hedgehogs referred to as wobbly hedgehog syndrome (WHS).4,5 This condition mainly affects hedgehogs ⬍2 years of age. The main clinical sign of WHS is progressive ataxia orig-
Figure 4. Hedgehog, case 4. Higher magnification of spinal cord in Figure 3. Note vacuolar change likely reflecting axonal edema (arrows), and a vacuole containing cellular debris (arrowhead). Hematoxylin and eosin (bar) ⫽ 120 m.
223
Intervertebral Disc Disease in African Hedgehogs
inating in the rear limbs. Histologically, there is demyelination primarily within the spinal cord. The underlying etiology for WHS is still unknown at the present time. Early clinical signs of hedgehogs with WHS are very similar to the clinical signs exhibited by the hedgehogs with IVD. It may be difficult to clinically differentiate IVD from early stages of WHS without the aid of radiographs or postmortem examination of the spinal column. One difference in the clinical presentation between hedgehogs with IVD and hedgehogs with WHS is that hedgehogs with IVD were typically older at the time of presentation than hedgehogs with WHS. A paralytic condition associated with demyelination in the central nervous system has also been reported in European hedgehogs (Erinaceus europaeus).8 The cause for this neurologic disease has not been determined at this time. The clinical signs of this disease are very similar to those noted in the hedgehogs with IVD and those described for hedgehogs with WHS. The primary difference in the European hedgehog demyelinating disease is the histologic presence of inflammation within the central nervous system, a feature neither noted in our hedgehogs with IVD nor in African hedgehogs with WHS. The purpose of this report was to present 4 cases of IVD in hedgehogs. Given the close similarities of the clinical signs of IVD and WHS in African hedgehogs, diagnostic imaging is recommended for all hedgehogs with progressive neurologic disease to screen for evidence of IVD. Histologic examination of the spinal column is helpful for detection of IVD and associated lesions in the spinal cord.
Acknowledgments We thank R. Brown at Histology Consulting Service for expertise in slide preparation, Jamie Kinion of Northwest ZooPath for data retrieval, and Christie Buie of Northwest ZooPath for photo editing and manuscript submission.
References 1.
2.
3.
4.
5. 6. 7.
8.
Raymond JT, White MR: Necropsy and histopathologic findings in 14 African hedgehogs (Atelerix albiventris): a retrospective study. J Zoo Wildl Med 30:273277, 1999 Raymond JT, Garner MM: Cardiomyopathy in captive African hedgehogs (Atelerix albiventris). J Vet Diagn Invest 12:468-472, 2000 Raymond JT, Garner MM: Spontaneous tumours in captive African hedgehogs (Atelerix albiventris): a retrospective study. J Comp Pathol 124:128-133, 2001 Graesser D, Spraker TR, Dressen P, et al: Wobbly hedgehog syndrome in African pygmy hedgehogs (Atelerix sp.). J Exotic Pet Med 15:59-65, 2006 Garner MM, Graesser D: Wobbly hedgehog syndrome. Exotic DVM 8:27-29, 2006 Simpson ST: Intervertebral disc disease. Vet Clin North Am Small Anim Pract 22:889-897, 1992 Palmer N: Bones and joints, in Jubb KV F, Kennedy PC, Palmer N (eds): Pathology of Domestic Animals (ed 4). San Diego, CA, Academic Press, Inc., pp 153158, 1993 Palmer AC, Blakemore WF, Franklin RJM, et al: Paralysis in hedgehogs (Erinaceus europaeus) associated with demyelination. Vet Rec 143:550-552, 1998