Cervical vertebral canal endoscopy in a horse with cervical vertebral stenotic myelopathy

A 3-year-old Thoroughbred gelding presented with a history of neurological signs, including incoordination in his hindlimbs, of about 7 months' duration. On initial examination, the horse exhibited ataxia and paresis in all limbs with more severe deficits in the hindlimbs. Cervical radiographs displayed severe osteoarthritis of the articular processes between C5 and C6. On subsequent cervical myelography the dorsal contrast column was reduced by 90% at the level of the intervertebral space between C5 and C6. Cervical vertebral canal endoscopy, including epidural (epiduroscopy) and subarachnoid endoscopy (myeloscopy), was performed under general anaesthesia. A substantial narrowing of the subarachnoid space at the level between C6 and C7 was seen during myeloscopy, while no compression was apparent between C5 and C6. Epiduroscopy showed no abnormalities. After completion of the procedure, the horse was subjected to euthanasia and the cervical spinal cord submitted for histopathological examination. Severe myelin and axon degeneration of the white matter was diagnosed at the level of the intervertebral space between C6 and C7, with Wallerian degeneration cranially and caudally, indicating chronic spinal cord compression at this site. Myeloscopy was successfully used to identify the site of spinal cord compression in a horse with cervical vertebral stenotic myelopathy, while myelography results were misleading.     

Cervical stenotic myelopathy in a horse

A 13-year-old, Thoroughbred gelding presented with a 3-year history of progressive ataxia of all 4 limbs. Physical and neurological examinations indicated a compressive lesion affecting the cervical spinal cord. Radiographs confirmed a lesion, and a myelogram a narrowing of the spinal canal at cervical vertebrae (6-7). Necropsy confirmed cervical stenotic myelopathy.     

Contrast-enhanced computed tomography and myelography in six horses with cervical stenotic myelopathy.

The cervical spines of 6 horses with cervical stenotic myelopathy (CSM) were examined using myelography and contrast-enhanced computed tomography (CECT). Histopathology of the spinal cord of these horses identified 10 neurologically significant compressive lesions. Myelography and CECT were both able to demonstrate all 10 spinal cord compressive lesions, but myelography falsely identified 2 sites and CECT falsely identified 1 site as compressive lesions of the spinal cord which were not supported by histopathology. Additional qualitative information was obtained by CECT regarding the source, severity and location of spinal cord compression. Computed tomography identified stenosis of the vertebral canal with circumferential loss of contrast agent and documented lateral compressive lesions of the spinal cord due to malformed articular facets. Compression of the peripheral nerve roots by malformed articular facets encroaching on the intervertebral foramen was easily identified by CECT in the axial plane. No compressive lesions were identified in 3 unaffected horses by either method. Minimum sagittal diameter (MSD) values obtained from CECT images were strongly correlated with necropsy measurements, validating CECT as an accurate method of obtaining MSD values. The MSD values in the CSM-affected horses were significantly narrowed (P less than 0.05) from C3C6 regardless of the site of spinal cord compression, when compared with the unaffected controls. This finding supports previous reports suggesting that generalised stenosis of the vertebral canal is an important feature in the pathogenesis of cervical stenotic myelopathy.     

Unilateral degenerative joint disease of a cervical articular process joint between the fourth and fifth cervical vertebrae causing asymmetrical ataxia in a young horse

A 5-year-old horse was examined for investigation of asymmetrical, quadrilateral ataxia and paresis. Clinical examination was unremarkable, and a thorough neurological examination localised the lesion to the cervical spine. Following this, magnetic motor evoked potentials were acquired to allow for latency times to be determined. Abnormal conduction times were found to the right thoracic and right pelvic limbs, confirming that the horse had an asymmetrical cervical spinal myelopathy. Radiographs were acquired to ensure that the horse had no significant pathology which would contraindicate general anaesthesia. There were no abnormalities noted on these, so the horse underwent contrast-enhanced computed tomography of its cervical spine which revealed enlargement of the right articular process joint between C4 and C5 with dorsolateral impingement of the spinal canal and cord. Due to the poor prognosis for future performance, the horse was subsequently euthanised. A post-mortem examination confirmed the findings of degenerative joint disease, with some unexpected changes seen on histology of the spinal cord. The unilateral right-sided compression had caused degenerative changes to ascending and descending tract bilaterally indicating a dynamic component to this lesion, which would be more commonly understood to be static.     

Frequency and severity of osteochondrosis in horses with cervical stenotic myelopathy

We compared the frequency and severity of osteochondrosis lesions in young Thoroughbred horses with cervical stenotic myelopathy (CSM) vs that in clinically normal Thoroughbreds of the same age. All lesions of the cervical vertebrae and appendicular skeleton were classified histologically as osteochondrosis or nonosteochondrosis and were measured for severity. Minimal sagittal diameter was significantly smaller in horses with CSM from C2 through C6; no difference was detected at C7. Severity of cervical vertebral osteochondrosis was greater in the horses with CSM, however frequency was not different. Frequency and severity of nonosteochondrosis lesions were not different in cervical vertebrae or appendicular skeleton. Frequency and severity of appendicular skeleton osteochondrosis lesions were both greater in horses with CSM. Osteochondrosis and nonosteochondrosis lesions were more severe on facets at sites of compression than on facets at noncompressed sites in horses with CSM. However, compression was also observed at sites with no articular facet lesions. The association of widespread osteochondrosis and spinal canal narrowing with CSM suggests CSM may represent a systemic failure in the development or maturation of cartilage and bone.     

Management of equine ataxia caused by cervical vertebral stenotic myelopathy: A European perspective 2010–2015

The diagnosis and therapy of cervical vertebral stenotic myelopathy (CVSM) are challenging and have been most frequently described in racehorses. We aimed to analyse CVSM cases presented for diagnostic work‐up and treatment in a nonracing horse population. We hypothesised that our diagnostic work‐up protocol including clinical/orthopaedic/neurological/radiographic and myelographic examinations may provide practical reference points for in vivo diagnosis/prognosis and adequate CVSM management. Medical records from 2010 to 2015 were reviewed retrospectively. Cases were included if our standardised work‐up protocol was followed, there was no evidence of any infectious diseases causing the neurological signs, and native cervical radiographs and myelograms confirmed CVSM. Age/breed/sex/type of performance/degree of neurological deficits and number/sites/quality/therapy of stenosis were recorded. Sixty‐two horses met the inclusion criteria. The majority of the horses were aged 5–10 years (44%) or >10 years (35%); nine horses (15%) were 1–4 years and four <1 year (6%) old. Forty‐six horses were Warmbloods (73%), 10 ponies (16%) and six of other breeds (11%). Males were more affected (69%) than females (31%). Sixty‐one percent were pleasure‐horses, 26% were sport‐horses and no information was available for 13%. Most cases presented with mild–moderate neurological signs (grade 2/5 = 18%, grade 2–3/5 = 31%). On myelograms, 23 horses (37%) had single‐level, 22 (35%) had double‐level, and eight (13%) triple‐level stenosis, while nine cases (15%) did not have stenosis. Fifty horses (55%) showed dynamic and 41 (45%) static stenosis. Dynamic stenosis was more common (46%) than static (29%) stenosis and/or combined stenosis (25%). Stenoses were more frequently observed in the mid‐to‐caudal vertebrae. Static stenoses tended to be located more caudally. Based on our protocol, 15% of horses were subjected to euthanasia without therapy, 62% treated conservatively and 23% underwent cervical ventral interbody fusion. In conclusion, our diagnostic work‐up protocol provided practical reference points for in vivo diagnosis/prognosis and adequate management of CVSM in a nonracing horse population.     

Osteochondromatosis of the cervical spine causing compressive myelopathy in a dog

A 10-month-old Alaskan malamute presented with cervical pain and hindlimb proprioceptive deficits. Plain and myelographic radiographic studies of the cervical spine demonstrated extradural compression of the spinal cord at the level of C7 and C5. Computed tomography assisted presurgical characterisation of the lesions as osteochondromatosis. Laminectomy permitted successful removal of the lesions.     

Ruptured capsule of the elbow joint of a draught horse

A cyst filled with fluid was found to be the cause of an enlarged antebrachium in a horse. Communication between the cyst and the elbow joint was demonstrated by: 1) finding, during radiographic examination of the elbow, radiopaque contrast solution instilled into elbow joint within the cyst; 2) finding cytological values in fluid aspirated from the cyst that were similar to those in fluid aspirated from the elbow joint; and 3) finding hyperechoic foci, assumed to be air bubbles, during ultrasonographic examination of the cyst after administration of air into the elbow joint. Communication of the cyst with the elbow joint was confirmed during post mortem examination of the affected limb.     

Postanesthetic hemorrhagic myelopathy in a horse

Acute hemorrhagic myelopathy developed in the sixth cervical to the eighth thoracic spinal cord segments of a 1-year-old Quarter Horse colt that was castrated under general anesthesia while in dorsal recumbency. Clinical signs were consistent with severe transverse myelopathy caudal to the brachial enlargement and cranial to the lumbosacral enlargement of the spinal cord. Histologic examination of the spinal cord revealed hemorrhage in the gray matter, with multiple blood-filled clefts in otherwise normal neuropil. Hemodynamic changes in the spinal cord associated with anesthesia and dorsal recumbency may have led to hypoxic vessel damage, with massive hemorrhage after surgery, when the horse was returned to lateral recumbency. Postanesthetic hemorrhagic myelopathy is a possible complication of positioning in dorsal recumbency, during anesthesia, in rapidly growing, young horses.     

Fibrocartilaginous embolic myelopathy in a horse

Fibrocartilaginous embolic myelopathy was diagnosed in a 11-year-old, male, Tennessee Walking Horse by histopathological examination of the spinal cord after the horse was killed because of severe neurological dysfunction. Both ventral funiculi of C6 and C7 cervical spinal cord had extensive necrosis with blood vessels containing fibrocartilaginous emboli. A similar fibrocartilaginous embolus was observed in a single large spinal artery adjoining the vertebral leptomeninges.     

Cholelith causing duodenal obstruction in a horse.

A 10-year-old Appaloosa stallion was referred for evaluation of colic. At admission, the heart rate, capillary refill time, respiratory rate, and rectal temperature were high. Fifteen liters of reflux was obtained by nasogastric intubation. Palpation of an abdominal mass per rectum elicited signs of pain. At exploratory laparotomy, a mass was palpated in the ascending portion of the duodenum. The small intestine ruptured at the site of obstruction during manipulation. The horse was euthanatized. A large cholelith was the cause of the duodenal obstruction. At necropsy, multiple choleliths of various sizes were found in the pancreatic and common bile ducts and in the stomach.     

Tarsocrural joint luxation in a horse.

A 14-year-old Quarter Horse x Thoroughbred gelding was admitted to the teaching hospital because of inability to bear weight on its right hind limb, associated with a severe deviation of the tarsus. The provisional diagnosis was tarsal joint luxation or fracture. Radiography revealed complete luxation of the tarsocrural joint. The luxation was reduced, using minimal force. The horse was confined to a box stall and was maintained in a full-length hind-limb cast for 33 days. Box stall confinement was continued for 3 months after removal of the cast. On reexamination 18 months after the injury, the horse had only mild lameness (grade 1 of 5), but had marked reduction in the range of motion of the tarsus. Radiography revealed extensive changes indicative of severe degenerative joint disease. The horse was still used occasionally as a light pleasure riding horse and maintained itself on pasture well.     

Endoscopic anatomy of the cervical vertebral canal in the horse: a cadaver study

Reason for performing study: Localisation of spinal cord compression in horses with cervical vertebral stenotic myelopathy is inexact. Vertebral canal endoscopy has been used in man to localise spinal cord lesions and has the potential to become a useful diagnostic technique in horses. Objective: To establish a surgical approach via the atlanto‐occipital space to the cervical vertebral canal in equine cadavers and describe the endoscopic anatomy of the cervical epidural and subarachnoid spaces. Methods: The cadavers of 25 mature horses were used to assess 3 surgical methods to approach the cervical vertebral canal, including 2 minimally invasive and one open technique. Once the approach had been made, a flexible videoendoscope was inserted into the epidural space (epiduroscopy) or the subarachnoid space (myeloscopy) and advanced caudally until the intervertebral space between C7 and T1 was reached. Results: The epidural and subarachnoid spaces could not be accessed reliably using the minimally invasive techniques. Furthermore, damage to the nervous tissues was a frequent complication with these procedures. The open approach allowed successful insertion of the videoendoscope into the epidural and subarachnoid spaces in all horses and no inadvertent damage was observed. Anatomical structures that could be seen in the epidural space included the dura mater, nerve roots, fat and the ventral internal vertebral venous plexus. In the subarachnoid space, the spinal cord, nerve roots, blood vessels, denticulate ligaments and external branch of the accessory nerve were seen. Conclusions: Using the open approach, epiduroscopy and myeloscopy over the entire length of the cervical vertebral canal are possible in the mature horse. Potential relevance: Cervical vertebral canal endoscopy may become a valuable tool to localise the site of spinal cord injury in horses with cervical vertebral stenotic myelopathy and could aid in the diagnosis of other diseases of the cervical spinal cord.     

Arthroscopic treatment for cervical articular process joint osteochondrosis in a Thoroughbred horse

A yearling Thoroughbred colt was presented for investigation of neck stiffness and episodes of intermittent neck pain without neurological signs. Osteochondrosis (OCD) of the cervical articular process joints (APJs) was diagnosed with the aid of radiography and computed tomography. An articular osteochondral fragment of the left fourth caudal cervical articular process was removed arthroscopically following a cut down approach to the joint capsule of the affected APJ. Surgical removal resulted in resolution of clinical signs at 4 weeks. However, subsequently the horse was markedly ataxic 6 weeks post surgery after being found cast in its stable. Cervical stenotic myelopathy was considered the most likely cause based on clinical and radiographic signs and the horse was subjected to euthanasia due to a poor prognosis for racing. Post‐mortem examination identified atypical cartilage within several cervical APJs with histological changes consistent with OCD. This case report supports OCD of the APJs as a cause of neck pain and confirms the clinical practicality and short‐term effectiveness of arthroscopic fragment removal. Surgical treatment for cervical OCD should be considered in horses without neurological signs, although case selection is important and the underlying pathology remains a risk factor for the development of subsequent neurological signs.