Vertebral canal and spinal cord mensuration: a comparative study of its effect on lumbosacral myelography in the dachshund and German shepherd dog

One hundred noncontrast spinal radiographic studies followed by myelography were evaluated to compare vertebral canal size and spinal cord location and size in a chondrodystrophic breed (50 Dachshunds) with those variables in a nonchondrodystrophic breed (50 German Shepherd Dogs). Measurements were made of the sagittal diameter (height) of the vertebral canal, sagittal diameter (height) of the spinal cord, and transverse diameter (width) of the spinal cord in the lumbar and sacral regions. Differences were detected in the craniocaudal location of maximal vertebral canal height and maximal spinal cord height. The spinal cords in the Dachshunds terminated further caudally than those in the German Shepherd Dogs. Location of maximal spinal cord width was different between the breeds, consistent with the apparent, more caudal termination of the cord in the Dachshunds. The ratio of spinal cord to vetebral canal heights was notably greater in the Dachshunds than in the German Shepherd Dogs. These differences in vertebral canal and spinal cord mensuration may influence the choice of radiographic technique and its interpretation. Injection sites may be selected further cranially in German Shepherd Dogs (L4-5) than in Dachshunds (L5-6).     

Diffuse idiopathic skeletal hyperostosis of the spine in a nine‐year‐old cat

A nine‐year‐old intact female domestic shorthair cat was evaluated for paraparesis, ataxia and severe spinal hyperaesthesia. Neurological examination indicated a T3‐L3 spinal cord segment lesion. Computed tomography of the thoracolumbar and lumbosacral vertebral column was performed. This showed contiguous smooth new bone formation ventral and lateral to the vertebrae extending from the cranial thoracic area to the lumbosacral junction and appearing similar to canine diffuse idiopathic skeletal hyperostosis. There was also marked dorsolateral stenosis of the vertebral canal at the level of T4‐T5 because of degenerative changes of the facet joints. To the authors’ knowledge, this is the first published report of feline diffuse idiopathic skeletal hyperostosis.     

Spinal dural ossification causing neurological signs in a cat

A six-year-old Ragdoll cat underwent examination due to a six-month history of slowly progressive gait abnormalities. The cat presented with an ambulatory tetraparesis with a neurological examination indicating a C1-T2 myelopathy. Radiographs of the spine showed a radiopaque irregular line ventrally in the vertebral canal dorsal to vertebral bodies C3-C5. In this area, magnetic resonance imaging revealed an intradural extramedullary/extradural lesion compressing the spinal cord. The spinal cord was surgically decompressed. The cause of the spinal cord compression was dural ossification, a diagnosis confirmed by histopathological examination of the surgically dissected sample of dura mater. The cat gradually improved after the procedure and was ambulating better than prior to the surgery. The cat’s locomotion later worsened again due to ossified plaques in the dura causing spinal cord compression on the same cervical area as before. Oral prednisolone treatment provided temporary remission. Ten months after surgery, the cat was euthanized due to severe worsening of gait abnormalities, non-ambulatory tetraparesis. Necropsy confirmed spinal cord compression and secondary degenerative changes in the spinal cord on cervical and lumbar areas caused by dural ossification. To our knowledge, this is the first report of spinal dural ossification in a cat. The reported cat showed neurological signs associated with these dural changes. Dural ossification should be considered in the differential diagnosis of compressive spinal cord disorders in cats.     

RELATIONSHIP OF CERVICAL SPINAL CORD DIAMETER TO VERTEBRAL DIMENSIONS: A RADIOGRAPHIC STUDY OF NORMAL DOGS

Cervical spinal cord abnormalities are often unapparent on myelographic studies, because no normal values for cervical spinal cord diameter are currently available. The purpose of this study was to establish, myelographically, the normal sagittal diameter of the cervical spinal cord in large and small breed dogs and its relationship to the sagittal diameter of the vertebral canal and sagittal height/length of the corresponding vertebral bodies. Forty-one adult dogs underwent cervical radiography and myelography. Spinal cord and vertebral canal sagittal diameter, vertebral body height at C2 to 5, body length at C3 to 5, and dorsal spine length of C2 were measured on lateral views. Ratios of spinal cord:vertebral canal diameter, spinal cord:body height, and spinal cord:body length/spine were calculated, and a normal range was determined for small and large breed dogs. The spinal cord:vertebral canal ratios showed that small breeds have a higher cervical cord-to-canal ratio than large breeds. The mean values and ranges of 14 ratios are reported. The ratios of spinal cord:body length at C2 to 4 in small breeds and spinal cord:body height at C3 to 5 in large breeds were found to be the most accurate for assessing spinal cord sagittal diameter. These normal ranges would allow quantitative and objective evaluation of the cervical spinal cord by myelography and early identification of dogs with altered spinal cord diameter, which could be further evaluated by means of alternative imaging techniques.     

Morphometry of the thoracic spine in German shepherd dog: a computed tomographic study

Computed tomographic images of the thoracic spine of 13 German shepherd dogs were examined in order to determine the thoracic spine morphometry. Examinations were carried out in the transverse plane both intervertebral and mid-vertebral levels of the each thoracic vertebrae. The dorsoventral and interpedicular diameters of the spinal canal, the dorsoventral and transverse diameters of the vertebral body, the dorsoventral and transverse diameters of the spinal cord and also the cross-section area of the spinal canal were measured. The maximum values were found to be at the level of C7-T1. The shapes of the spinal canal and cord were circular in middle part, the shape became transverse oval in the cranial and caudal parts of the thoracic spine. The most significant correlation between the diameters was found to be in male dogs, except between dorsoventral diameters of the spinal canal and that of the vertebral body and between dorsoventral diameters of the spinal canal and transverse diameters of the vertebral body.     

Vertebral stabilization using positively threaded profile pins and polymethylmethacrylate, with or without laminectomy, for spinal canal stenosis and vertebral instability caused by congenital thoracic vertebral anomalies

Objective— To describe diagnostic findings, surgical technique, and outcome in dogs with thoracic spinal canal stenosis and vertebral instability secondary to congenital vertebral anomalies.
Study Design— Retrospective clinical study.
Animals— Dogs (n=9) with thoracic spinal canal stenosis.
Methods— Medical records (1995–1996; 2000–2006) of 9 dogs with a myelographic diagnosis of spinal canal stenosis and/or vertebral instability secondary to congenital vertebral anomaly that were surgically managed by vertebral stabilization with or without laminectomy were reviewed. Data on pre- and postoperative neurologic status, diagnostic findings, surgical techniques, and outcomes were retrieved. Follow-up evaluations were performed at 1, 2, and 6 months. Long-term outcome was assessed by means of clinical examination or owner telephone interviews.
Results— Spinal cord compression was confirmed by myelography, and in 2 dogs, dynamic compression by stress myelography. Eight dogs regained the ability to ambulate postoperatively. One dog with a partial recovery regained voluntary movement but did not become ambulatory.
Conclusions— Spinal cord injury secondary to congenital vertebral anomaly may have a good outcome when treated by vertebral stabilization with or without laminectomy. Adequate stabilization of the vertebrae and improved neurologic outcome were achieved in most dogs.
Clinical Relevance— Vertebral stabilization using positively threaded profile pins and polymethylmethacrylate with or without laminectomy is an effective treatment for spinal canal stenosis and vertebral instability secondary to congenital thoracic vertebral anomalies.     

Chronic spinal epidural abscess in a cat: a case report with an unusual imaging finding

A 1-year-old domestic shorthair cat was evaluated for a chronic history of back pain, dysuria, and paraplegia. Radiographic and computed tomographic examinations showed circumferential widening of the vertebral canal at T13 and T14. A spinal epidural abscess (SEA) compressing the spinal cord from the level of T11 to L1 was suspected following intravenous contrast administration, and was confirmed by surgical exploration and histopathological analysis. The cat recovered its motor and bladder functions following surgical decompression and antibiotic therapy. SEA is a neurological emergency requiring prompt treatment. However, the present case had a prolonged disease course and pressure atrophy of the vertebrae was strongly suspected. To our knowledge, this imaging finding has not been reported in dogs or cats with SEA.     

Thoracolumbar spinal cord compression due to vertebral process degenerative joint disease in a family of Shiloh Shepherd dogs

Five young Shiloh Shepherd Dogs (4 males and 1 female) related by a common sire were studied because of progressive pelvic limb weakness and incoordination. All dogs had a spastic paraparesis and pelvic limb ataxia consistent with an upper motor neuron and general proprioceptive lesion between spinal cord segments T3 and L3. Proliferative lesions involving one or more of the articular processes from the 11th thoracic vertebrae to the 2nd lumbar vertebra were observed on radiographs of the thoracolumbar vertebrae. Dorsal compression of the spinal cord was identified during imaging studies at these sites. Abnormalities of the synovial joints and bony proliferation of the involved articular processes were identified at postmortem examination in 2 dogs. The articular processes and associated vertebral arches protruded into the vertebral canal, indenting the dorsal surface of the spinalcord. Degenerative joint disease (DJD) was identified histologically. A compressive myelopathy was diagnosed in the spinal cord. These dogs were affected by a compressive myelopathy as a consequence of vertebral process DJD that likely has a geneticcomponent. The DJD could have been caused by a primary vertebral malformation or an injury to the processes at a young age causing malarticulation.     

Dynamic Compression of the Cervical Spinal Cord: A Myelographic and Pathologic Investigation in Great Dane Dogs

The authors report the radiographic and pathologic findings in 10 Great Dane dogs with the wobbler syndrome. In all 10 dogs it was possible to demonstrate myelographically that there was cervical spinal cord compression at 1 or 2 sites. The spinal cord compression was mainly dynamic in nature, as degree of compression increased in extension and decreased in flexion of the neck in 8 dogs. In 1 dog with deformed vertebral bodies (G6 and C7), compression increased slightly in flexion of the neck. In another dog, compression was lateral and could only be seen in the ventrodorsal view.The macroscopic findings substantiated the radiologic findings. The cause of the spinal cord compression was in 8 dogs a decrease in the dorsoventral diameter of the orifice of the vertebral canal of 1 or 2 vertebrae in combination with deformation and elongation of 1 or several vertebral arches. In extension of the neck, the cervical spinal cord was squeezed between the anterior tip of the elongated vertebral arch and the caudodorsal rim of the body of the adjacent cranial vertebra.Histologic examination was made of the spinal cord in 5 dogs and the compressive lesions that were found could explain the neurologic signs.In the discussion, the question is raised as to why pain is not a prominent sign in dogs with the wobbler syndrome in contrast to in dogs with cervical disc protrusion. It is believed that the inflammatory foreign body reaction, triggered by the protruded calcified nucleus pulposus is the main cause of pain in the disc protrusion syndrome. In the wobbler syndrome there is no obvious inflammatory reaction in the epidural space.Finally, the possible etiologic factors oC importance for the deformation oC the cervical vertebrae in wobblers are discussed. There are indications that both overnutrition and a genetic trait for rapid growth are of importance.     

Computed tomographic evaluation of cervical vertebral canal and spinal cord morphometry in normal dogs

The height, width, and cross-sectional area of the vertebral canal and spinal cord along with the area ratio of spinal cord to vertebral canal in the cervical vertebra were evaluated in images obtained using computed tomography (CT). Measurements were taken at the cranial, middle, and caudal point of each cervical vertebra in eight clinically normal small breed dogs (two shih tzu, two miniature schnauzers, and four mixed breed), 10 beagles, and four German shepherds. CT myelography facilitated the delineation of the epidural space, subarachnoid space, and spinal cord except at the caudal portion of the 7th cervical vertebra. The spinal cord had a tendency to have a clear ventral border in the middle portion of the vertebral canal and lateral borders near both end plates. The height, width, and area of the vertebral canal and spinal cord in the cervical vertebra were increased as the size of dog increased. However, the ratio of the spinal cord area to vertebral canal area in the small dogs was higher than that of the larger dogs. Results of the present study could provide basic and quantitative information for CT evaluation of pathologic lesions in the cervical vertebra and spinal cord.     

Multiple myeloma with central nervous system involvement in a cat

CASE DESCRIPTION: A 1.5-year-old spayed female domestic shorthair cat was admitted for hind limb locomotor difficulties and signs of pain along the lumbar portion of the vertebral column. At the time of referral, the cat was paraparetic with deficits in the spinal reflexes of the hind limbs. Neuroanatomic localization was at the L6-S2 spinal cord segments, corresponding approximately to the region of the L4-L6 vertebral bodies. CLINICAL FINDINGS: Radiography revealed a mixed osteolytic-proliferative lesion within the body of L5 involving the cranial end plate, as well as punctate radiolucencies in the distal portion of the femur. Magnetic resonance imaging revealed an intramedullary spinal cord lesion along with extensive meningeal and nerve root lesions in the area of the L4-L6 vertebral bodies. Cytologic analysis of a bone marrow aspirate from the right trochanteric fossa revealed a substantial plasma cell infiltrate. Analysis of CSF revealed a high protein concentration and morphologically abnormal plasma cells. Urine, but not serum, protein electrophoresis revealed a sharp gamma-globulin peak consistent with a monoclonal band of Bence-Jones proteins. The diagnosis was multiple myeloma. TREATMENT AND OUTCOME: The cat was treated with melphalan and prednisolone. A rapid clinical response was reported, and by week 3 after diagnosis, the cat's locomotion and behavior had normalized. However, by month 4, multifocal neurologic deficits were evident. The cat was euthanized at 9 months because of tetraparesis and substantial weight loss. CLINICAL RELEVANCE: To our knowledge, this is the first report of myeloma in a cat that had electrophoretically detectable light chain proteinuria but lacked a detectable serum monoclonal gammopathy.     

Malignant peripheral nerve sheath tumor arising from the spinal canal in a cat

A 10-year-old female mongrel cat with back pain was brought to the Nihon University Animal Medical Center. Palpation demonstrated a mass in the back region. Radiography revealed partial destruction of the processus spinosus and the arch of the T8 and T9 vertebrae. On magnetic resonance imaging, the mass was found to have compressed the spinal cord and extended to the outside of the spinal canal. We performed extirpation of the mass, and confirmed that it arose from the spinal canal. Histopathologically, the mass was a malignant peripheral nerve sheath tumor.     

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.     

Intramedullary Intervertebral Disk Extrusion in a Cat

Intervertebral disk extrusion is rarely reported in the cat. In this case, the clinical, radiologic, and magnetic resonance imaging findings of an acute intramedullary intervertebral disk extrusion in a 5-year-old domestic shorthaired cat are described. Radiographically, there was mineralized disk material within the vertebral canal. On magnetic resonance images, the disk material was found to be within the spinal cord. A linear disk trail extending from the disk space into the spinal cord may be specific for intramedullary disk extrusion.     

Fibrocartilaginous embolism in a cat

A nine-year-old cat was presented with a history of an acute onset of paraplegia. On the basis of the neurological examination, the lesion was localised between the fourth lumbar and third sacral segments (L4 to S3) of the spinal cord. Investigations included radiography, myelography, cerebrospinal fluid analysis, routine haematology and biochemistry, feline leukaemia virus testing and urinalysis. A definitive diagnosis was not achieved and the cat was euthanased 12 days after presentation. Post mortem examination revealed infarction of the spinal cord secondary to fibrocartilaginous embolisation. This is the first reported case of fibrocartilaginous embolism in the cat in the UK.     

Morphometric dimensions of the caudal cervical vertebral column in clinically normal Doberman Pinschers, English Foxhounds and Doberman Pinschers with clinical signs of disk-associated cervical spondylomyelopathy

Client-owned, clinically normal Doberman Pinschers (n=20), English Foxhounds (n=17), and Doberman Pinschers with clinical signs of disk-associated cervical spondylomyelopathy (DA-CSM) (n=17) were prospectively studied. All dogs underwent magnetic resonance imaging (MRI) of the cervical vertebral column. To evaluate vertebral canal stenosis, the canal occupying ratios of the spinal cord and cerebrospinal fluid (CSF)-column were calculated from C5 to C7. To evaluate the degree of spinal cord compression and the amount of canal compromise, the compression ratio, remaining spinal cord and CSF-column area, and vertebral canal and dorsoventral vertebral canal compromise ratios were calculated at the site of most severe compression. For each canal occupying ratio, there was a significant higher value (implicating less space available for the spinal cord in the vertebral canal) at the level of C7 for clinically affected Doberman Pinschers compared with clinically normal English Foxhounds. The remaining spinal cord area was significantly smaller in dogs with clinically relevant spinal cord compression compared to dogs with clinically irrelevant spinal cord compression. Relative stenosis of the caudal cervical vertebral canal occurred more often in Doberman Pinschers with DA-CSM compared to English Foxhounds and a critical degree of spinal cord compression should be reached to result in clinical signs.     

The 3D anatomy of the cervical articular process joints in the horse and their topographical relationship to the spinal cord

Reasons for study: Detailed anatomy of the equine cervical articular process joints (APJs) has received little attention in the literature and yet disorders of this joint have been linked to spinal cord compression resulting in severe clinical signs such as ataxia and weakness. This study aimed to describe the 3D anatomy of the APJ in relation to the spinal cord in the horse. Hypothesis: Artificial distension of the APJ causes the joint pouches to extend into the vertebral canal, with the potential for APJ effusion to cause spinal cord compressive disease. Methods: Six cadaveric necks (C1–C7) of clinically normal horses were used in this study. Computed tomography scans of the cervical APJ were acquired after injection of a negative contrast agent to maximal distension. The resulting images were semi‐automatically segmented using greyscale thresholding and reconstructed in 3D by polygonal surface meshing. The 3D reconstructions were used to assess the topographic anatomy of the APJ in relation to the spinal cord and to measure joint volume at each cervical vertebra in relation to vertebrae size. Results: Joint volume varied significantly between joint location (P<0.0001) and was positively correlated to the vertebral site (from cranial to caudal) (r = 0.781, P<0.0001). After distension, the medial outpouch of the APJ extended towards the vertebral canal from a dorsolateral location but in none of the 6 horses was there apparent compression of the dura mater surrounding the spinal cord. There was no significant difference in the extent of medial outpouch at any vertebral level (P = 0.104). Flexion of the neck resulted in minor changes to the shape of the APJ but did not result in the medial outpouch encroaching any closer to the spinal cord. Conclusions: From this study, it appears that in the absence of any other soft tissue or bony changes an effusion of the APJ is unlikely to cause spinal cord compression. However, given that the APJ and spinal cord are in close approximation, in the presence of other anatomical changes, an effusion may have the potential to cause compression. Potential relevance: This study confirms that the APJ extend into the dorsolateral aspect of the vertebral canal in a ventromedial direction, suggesting that oblique myelographic views are recommended for the diagnosis of spinal cord compression when pathology of the APJ is suspected.     

Dorsal laminar elevation as a treatment for cervical vertebral canal stenosis in the dog

A five-month-old Great Dane was presented with marked ataxia and paraparesis. Dynamic radiographic studies showed instability between the fifth and sixth cervical vertebrae and a myelogram revealed spinal cord compression at the sixth cervical vertebral foramen. Dorsal laminar elevation was used in conjunction with articular facet fusion to decompress the spinal cord and stabilise the affected vertebrae. There were no postoperative complications and the dog improved to normality before dying of an unrelated condition seven months after surgery.     

Gurltia paralysans (Wolffhügel, 1933): description of adults and additional case reports of neurological diseases in three domestic cats from southern Chile

Adults of Gurltia paralysans were obtained from veins of the spinal cord subarachnoid space from three domestic cats presenting with chronic paraparesis/paraplegia from rural areas of southern Chile. Four adult nematodes were collected (2 males and 2 females) were recovered from cat 1, 14 adult nematodes (12 females and 2 males) from cat 2, and 12 nematodes (10 females and 2 males) were collected from cat 3. Parasite induced lesions that compromised subarachnoid vein microvasculature at the thoracic, lumbar, sacral spinal cord segments extending to conus medularis. Female nematodes measured 25 mm long (range=25-30 mm) and 0.1mm wide. Male measured a mean of 16 mm length (range=13-18 mm) with a body diameter of 0.1mm (range=0.08-0.15 mm). The present study described structural features of G. paralysans, a rare parasite first reported in the 1930s, and provides additional reports on associated clinical and pathological findings in naturally infected domestic cats.