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Intervertebral Disc Disease in AfricanHedgehogs (Atelerix albiventris):Four CasesJames 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

at a North

220

Abstract

Four, adult, captive, African hedgehogs (Atelerix albiventris) were diagnosed with inter-vertebral disc disease. Clinical signs associated with intervertebral disc disease wereprogressive hindlimb ataxia, urinary stasis, loss of proprioception, and lameness.Radiographs on 2 of the cases revealed narrowing of the cervical intervertebral spacesand spondylosis. Histologically, all hedgehogs had several intervertebral discs that weredegenerative and protruded dorsally into the vertebral canal, which, in some cases, causedcompressive damage to the spinal cord. The clinical signs exhibited by the animals de-scribed in this report were similar to the signs of wobbly hedgehog syndrome. Based on thiscase series, clinical evaluation for disc disease is recommended in hedgehogs with signs ofambulatory dysfunction. Copyright 2009 Elsevier Inc. All rights reserved.

Key words: ataxia; Atelerix albiventris; degenerative; hedgehog; intervertebral disc disease

African hedgehogs (Atelerix albiventris) are a pop-ular exotic pet, as well as a small mammal com-monly exhibited by many zoological parks. Dis-

eases such as neoplasia, chronic interstitial nephritis,and cardiomyopathy are commonly diagnosed in cap-tive, adult hedgehogs.1-3 Recently, a neurologic condi-tion of unknown cause referred to as wobbly hedgehogsyndrome (WHS) has been noted in captive hedge-hogs.4,5 We report herein the first cases of interverte-bral disc disease (IVD) in hedgehogs, which, in someinstances, clinically resembles WHS.

Case Reports

Case 1 involved a 6.5-year-old male hedgehog housed

ern Californian zoological park that devel-

Journal of E

oped peripheral vestibular disease characterized byataxia that initially responded to supportive care andcorticosteroids for several months after presentationof the problem. Radiographs revealed narrowing ofC2-C3 and C3-C4 intervertebral spaces and spondy-

From the Northwest ZooPath, Snohomish, WA USA; the AudubonZoo, The Audubon Nature Institute, New Orleans, LA USA; the SanFrancisco 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: zoopath@aol.com.

© 2009 Elsevier Inc. All rights reserved.1557-5063/09/1803-$30.00

doi:10.1053/j.jepm.2009.06.007

xotic Pet Medicine, Vol 18, No 3 ( July), 2009: pp 220-223

Intervertebral Disc Disease in African Hedgehogs 221

losis between C2 and C3 (Fig 1). In April 2001, thehedgehog had another episode of neurologic dis-ease that was unresponsive to treatment and 2months later was humanely euthanized. At necropsy,the lungs were congested and the liver was pale withincreased firmness. The kidneys had cortical in-farcts, and the hedgehog’s adrenal glands were en-larged.

Case 2 was a 4-year-old female hedgehog from thesame Northern Californian zoological park that de-veloped lameness in the left front limb. Radiographsrevealed spondylosis between C2 and C3 and C4 andC5 and narrowing of C4-C5 intervertebral space withincreased radiodensity (mineralization) of the inter-vertebral disc. For humane reasons, the hedgehogwas euthanized. At necropsy, the hedgehog was ingood body condition, had slightly enlarged kidneys,pinpoint consolidation of the left caudal lung, and a3-cm mass infiltrating the dorsocervical and ret-roscapular soft tissues.

Case 3 was a male, approximately 4-year-old hedge-hog from a zoological park in the southeastern UnitedStates that had a prolonged history of urinary blad-der atony with urinary stasis and progressive bilateralhindlimb ataxia with loss of proprioception. Eutha-nasia was performed for humane and diagnostic pur-poses. At necropsy, there was severe distention of theurinary bladder and a 1-cm area of dark discolora-tion on the spleen. Longitudinal sections of thelumbar spine revealed expansion of adjacent inter-

Figure 1. Hedgehog, case 1. Radiographic image showing focus ofintervertebral disc disease in cervical vertebral column. Note nar-rowing of disc spaces at C2 to C3 and C3 to C4 (arrows) andspondylosis.

vertebral joints associated with thickening and white

discoloration of the intervertebral discs. Affecteddiscs were partially prolapsed into the spinal canal,and the adjacent spinal cord was dorsally displacedand slightly compressed (Fig 2).

Case 4 was an approximately 6-year-old malehedgehog from a zoological park in the MidwesternUnited States that was humanely euthanized becauseof infiltrative, oral squamous cell carcinoma. At nec-ropsy, there was a segment of cervical spine that hadtwo small, hard, 0.5-mm ventral protrusions inter-preted as spondylosis.

Tissues from the 4 hedgehogs were submitted toNorthwest ZooPath fixed in 10% neutral bufferedformalin. Northwest ZooPath subsequently decalci-fied 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 eo-sin. Histologically, all hedgehogs described in this re-port had multiple intervertebral disc degeneration ofthe nucleus pulposus and annulus fibrosus, fissuresand neovascularization in the annulus fibrosus, andmild to moderate, dorsal extrusion of the annulusfibrosus and nucleus pulposus into the spinal canal.Some of the intervertebral discs were incompletelyprotruded and still covered by thin layers of annulusfibrosus. Some of the completely protruding inter-vertebral discs had replacement of the mucinousnucleus pulposus by irregularly mineralized andfragmented cartilaginous tissue. In cases 1 to 3, thecervical vertebrae were primarily affected. In addi-tion, case 4 had similar degenerative disc lesions inthe lumbar vertebral column (Fig 3). Three hedge-hogs had ventral bridging osteophytes (spondylosis)between cervical vertebrae with degenerate interver-tebral discs. In all cases, there was mild to moderatemultifocal compression of the spinal cord by thedorsally protruding disc material. The compressed

Figure 2. Hedgehog, case 3. Note thickening and calcification ofintervertebral discs in the lumbar spinal column (arrows), with partialdisc proptosis and associated compression of the spinal cord

(arrowhead).

222 Raymond et al

spinal cord had multifocal axonal swelling, edema,and digestion chambers (Fig 4), and these lesionswere more severe in the lateral and ventral funiculi.Case 2 had several spinal nerve roots that had de-generate and swollen axons. Case 1 also had a fibro-cartilaginous embolus within a longitudinal venoussinus.

Discussion

Intervertebral disc disease is a progressive debilitat-ing condition that involves the degeneration of oneor more intervertebral discs. Ultimately, there is dor-sal protrusion of the damaged discs that results incompressive damage to the spinal cord. The diseaseusually manifests by progressive neurologic signs in-cluding loss of proprioception, ataxia, paresis, and,in some cases, paralysis. Hindlimb ataxia with pro-gression to paresis and paralysis, as noted in case 3,is a common clinical sign in dogs with IVD.6 Also, theurinary bladder atony in case 3 was likely due tocompressive damage to spinal nerve roots from her-niated disc material in the lumbosacral region. Neu-rogenic distension of the urinary bladder is a com-mon sequela to lumbar disc herniation in dogs. Theforelimb lameness in hedgehog 2 was from compres-sion of cervical spinal nerve roots by the prolapsedintervertebral disc. The vestibular signs (e.g., ataxia)in case 1 can be attributed in part to the spinal corddamage from the histologically observed protruding

Figure 3. Hedgehog, case 4. Tangentially sectioned lumbar spinalcolumn. Note complete degeneration of lumbar intervertebral disc,thickening of the joint space (j), and nodular cartilaginous materialabove the joint (arrows) that extends into the vertebral canal. Thespinal cord (c) has some vacuolar change corresponding to axonaldegeneration. The adjacent intervertebral disc (d) is normal. Hema-toxylin and eosin (bar) � 300 �m.

cervical intervertebral discs. The clinical signs exhib-

ited by these hedgehogs with IVD were directly re-lated to the compressive damage to the spinal cordand spinal nerve roots by the herniated disc mate-rial.

Although myelography is the diagnostic tech-nique of choice for IVD, standard radiographs of thevertebral column helped make a clinical diagnosis ofIVD in cases 1 and 2. Spinal radiographs made forevaluation of IVD in hedgehogs should include lateralviews of the cervical and lumbar regions. Fortunately,hedgehogs are small enough that the entire spine canbe visualized on one lateral radiographic view. Radio-graphs were not available for cases 3 and 4.

Intervertebral disc disease in the hedgehogs de-scribed in this report had histologic features of chon-drodystrophic breed–associated disc disease in canids.In all of the hedgehogs, there was replacement of themucinous component of the nucleus pulposus withcartilage-like tissue that eventually became mineral-ized. This is a characteristic lesion described in chon-drodystrophic dogs with IVD.7 Spondylosis, as notedin 3 hedgehogs, develops in ongoing cases of IVDbecause of the creation of abnormal movement be-tween vertebrae from degeneration of the annulusfibrosis and from inflammation with bone prolifera-tion elicited by ventrally protruding disc material.Case 1 had fibrocartilaginous embolus, which hasbeen noted in large-breed dogs with herniated frag-ments of nucleus pulposus.

Recently, there has been an emergence of a con-dition in captive African hedgehogs referred to aswobbly hedgehog syndrome (WHS).4,5 This condi-tion mainly affects hedgehogs �2 years of age. Themain clinical sign of WHS is progressive ataxia orig-

Figure 4. Hedgehog, case 4. Higher magnification of spinal cord inFigure 3. Note vacuolar change likely reflecting axonal edema(arrows), and a vacuole containing cellular debris (arrowhead). He-

matoxylin and eosin (bar) � 120 �m.

Intervertebral Disc Disease in African Hedgehogs 223

inating in the rear limbs. Histologically, there isdemyelination primarily within the spinal cord. Theunderlying etiology for WHS is still unknown at thepresent time. Early clinical signs of hedgehogs withWHS are very similar to the clinical signs exhibitedby the hedgehogs with IVD. It may be difficult toclinically differentiate IVD from early stages of WHSwithout the aid of radiographs or postmortem exam-ination of the spinal column. One difference in theclinical presentation between hedgehogs with IVDand hedgehogs with WHS is that hedgehogs withIVD were typically older at the time of presentationthan hedgehogs with WHS.

A paralytic condition associated with demyelina-tion in the central nervous system has also beenreported in European hedgehogs (Erinaceus euro-paeus).8 The cause for this neurologic disease has notbeen determined at this time. The clinical signs ofthis disease are very similar to those noted in thehedgehogs with IVD and those described for hedge-hogs with WHS. The primary difference in the Eu-ropean hedgehog demyelinating disease is the histo-logic presence of inflammation within the centralnervous system, a feature neither noted in ourhedgehogs with IVD nor in African hedgehogs withWHS.

The purpose of this report was to present 4 casesof IVD in hedgehogs. Given the close similarities ofthe clinical signs of IVD and WHS in African hedge-hogs, diagnostic imaging is recommended for allhedgehogs with progressive neurologic disease toscreen for evidence of IVD. Histologic examinationof the spinal column is helpful for detection of IVD

and associated lesions in the spinal cord.

Acknowledgments

We thank R. Brown at Histology Consulting Servicefor expertise in slide preparation, Jamie Kinion ofNorthwest ZooPath for data retrieval, and ChristieBuie of Northwest ZooPath for photo editing andmanuscript submission.

References

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