Cutaneous innervation of the thorax and abdomen of the dog

The anatomy of the cutaneous nerves innervating the canine thorax and abdomen was investigated by gross dissection of 38 dogs. Additionally, the cutaneous areas innervated by the thoracic and abdominal cutaneous nerves were mapped in a 2nd group of 33 barbiturate-anesthetized male dogs, using electrophysiologic techniques. The skin of the thorax was innervated by dorsal cutaneous branches, lateral cutaneous branches, and ventral cutaneous branches of the spinal nerves. The dorsal cutaneous branches were branches of the dorsal primary branches of spinal nerves C6 and T2 through T11. The lateral cutaneous branches were branches of the ventral primary branches of spinal nerves T2 through T12. The ventral cutaneous branches were branches of the ventral primary branches of spinal nerves T2 through T10. The skin of the abdomen was innervated by dorsal and lateral cutaneous branches of spinal nerves T12 through L3 (and occasionally L4). The cutaneous areas of the dorsal cutaneous branches occupied the dorsal half of the scapular and thoracic regions and the dorsal 2/5 of the abdominal region. The cutaneous areas of the lateral cutaneous branches covered the major portion of the ventral half of the thorax and the ventral 3/5 of the abdomen. The cutaneous areas of the ventral cutaneous branches occupied the axilla and the ventral part of the thoracic wall.     

Structural and biochemical changes in a spinal myelinopathy in twelve English foxhounds and two harriers

Degenerative lesions in the spinal cord white matter of 12 English Foxhounds and two Harriers between 3 and 6 years old were associated with a diet composed mainly of ruminant stomachs. Lesions were present throughout the length of the spinal cord and were more severe in ventral and lateral columns than in dorsal columns. Degenerate fibers were accompanied by astrocytic proliferation. Changes suggestive of a primary myelinopathy included vacuolated myelin sheaths around apparently intact axons and thick-thin transitions in myelin sheath thickness. Mixed sensory and motor peripheral nerves and muscle histochemical fiber type profiles appeared normal. Similarities were noted with the changes described in subacute combined degeneration of the spinal cord in human beings, a neuropathy caused by methionine and methylation deficiency in patients with vitamin B12 deficiency. Mean serum methionine levels were significantly lower (P greater than 0.01) and mean liver methionine synthetase levels were significantly greater (P greater than 0.01) in affected dogs restored to a balanced diet than in age-matched controls maintained on the balanced diet. The elevated methionine synthetase levels possibly reflected compensatory reactions to the associated dietary change.     

Chronic cervical compressive myelopathy in horses: clinical correlations with spinal cord alterations

Histological examination was performed on the cervical spinal cord from 13 horses with chronic cervical compressive myelopathy of 4 to 29 months duration. Structural alterations were correlated with clinical features. At the level of compression, the spinal cord was grossly deformed. Histological alterations included nerve fibre swelling and degeneration, occasional spheroids, astrocytic gliosis, increased macrophage activity and increased perivascular collagen. Myelin degeneration or loss at the level of the compressive lesion was greatest in the ventral and lateral funiculi and less consistently present in the dorsal funiculi. Asymmetry of lesions in the dorsal funiculi was associated with asymmetry of clinical signs in 5 horses. Histological alterations in areas of Wallerian degeneration were similar to that at the level of spinal cord compression, except that perivascular collagen was not increased. Wallerian degeneration was present cranial to the compressed site in the superficial portions of the lateral funiculi and in the middle of the dorsal funiculi. Caudal to the compressed site it was present in the ventral funiculi adjacent to the ventral median fissure and in the middle of the lateral funiculi. Deformation of the spinal cord did not correlate with the severity or duration of clinical signs but was positively correlated with the amount of perivascular collagen increase. The amount of nerve fibre swelling was not correlated with the severity of clinical signs but was negatively correlated with their duration. A rapid loss of nerve fibres apparently occurred early in the course of compression, since there was a marked decrease in the amount of nerve fibre swelling and Marchi stained degenerating myelin with increasing clinical duration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early Embryonic Development of the Camel Lumbar Spinal Cord Segment

The lumbar spinal cord segment of the camel embryo at CVRL 2.4 to 28 cm was examined. Major changes are occurring in the organization of the lumbar spinal cord segments during this early developmental period. At the CVRL 2.4, 2.7 and 3.6 cm the three primary layers, ependymal cells layer, mantle cells layer, marginal cells layer in the developing lumber spinal cord segment were demonstrated. The mantle layer is the first to show striking differentiation, while the marginal layer is represented by thin outer rim. Proliferation and differentiation of the neuroepithelial cells in the developing spinal cord produce the thick lateral walls, thin roof and floor plates. The spinal ganglion and dorsal root of the spinal nerve are differentiated. At 2.7 cm CVRL differential thickening of the lateral walls produces a shallow longitudinal groove called sulcus limitans , which separates the dorsal part (alar plate) from ventral part (basal plate). The ventral root of the spinal nerve, the spinal cord and ganglion are embedded in loose mesenchyme, which tends to differentiate into spinal meninges. At 3.6 cm CVRL the basal plate, which is the future ventral gray horn, seem to be quite voluminous and the dorsal and ventral roots unite to form the beginning of the spinal nerve. At 5.5 cm CVRL the alar plates enlarge forming the dorsal septum. At 8.4 cm to 10.5 cm CVRL the basal plates enlarge, and bulge ventrally on each side of the midline producing the future ventral medium fissure, and the white and gray matters can be recognized. At 28 cm CVRL the lumen of the spinal cord is differentiated into the central canal bounded dorsally and ventrally by dorsal and ventral gray commissures, and therefore the gray matter takes the appearance of a butterfly.The lumber spinal nerve and their roots are well distinguished.     

INTRACRANIAL EPIDERMOID CYST AND SYRINGOHYDROMYELIA IN A DOG

A 5-year-old female Cocker Spaniel dog had a sudden onset of vestibular disease that localized to the caudal fossa. Upon computed tomography of the brain, a large, hypoattenuating mass with a slight peripheral ring enhancement pattern was detected ventral to the cerebellum. A hypoattenuating region was also identified in the center of the C2 spinal cord segment, consistent with syringohydromyelia. Postmortem examination of the brain revealed a fluid filled, cystic mass located dorsal to medulla oblongata that caused severe compression of the overlying cerebellum. The histopathologic diagnosis was an epidermoid cyst. Extensive syringohydromyelia and obstructive hydrocephalus were identified, both thought to be secondary to overcrowding of the caudal fossa.     

Myelopathy and vitamin E deficiency in six Mongolian wild horses

Degenerative myelopathy was diagnosed in six Mongolian wild horses. Three of the horses had a history of ataxia dating from birth to 3 months of age. The clinical signs were uncoordinated movement of the hindlimbs and an abnormally wide-based gait and stance. The other 3 horses had mild ataxia. There were no gross lesions in the brain, vertebrae, or spinal cord. Histologic examination revealed degeneration of the neural processes in the ventral and lateral funiculi of all 6 horses. Myelin sheaths were dilated and vacuolated, and there were swollen, fragmented, or lysed axons. Neuronal degeneration, phagocytosis, and accumulation of periodic acid-Schiff-positive, xylol-insoluble lipopigment were observed in the affected neurons of the dorsal root ganglia. The plasma alpha-tocopherol values of 5 of the affected horses ranged from less than 0.03 to 0.08 (mean, 0.04 +/- 0.01) mg/dl. Seven clinically normal horses from the same herd had a range of less than 0.03 to 0.3 (mean, 0.11 +/- 0.02) mg/dl, which was low enough to be considered deficient.     

Mm. Intertransversarii eervicis of the ox (Bos taurus L.)

The cervical intertransverse muscles and their nerve supply are described and illustrated in the ox. The literature is reviewed and the principles of subdividing these muscles are discussed. They are divided into dorsal and ventral intertransversarii according to their innervation. The Mm. intertransversarii dorsales cervicis arise from the articular processes of C7-C3, follow a craniolateral course and insert by means of 1–4 fascicles on the transverse processes of preceding vertebrate including the atlas. They are innervated by the dorsal rami of cervical spinal nerves. The Mm. intertransversarii ventrales cervicis are grouped into medial and lateral parts. The medial part consists of short fascicles which extend between contiguous transverse processes from C7-C2. They are pierced by the emerging ventral branches of the spinal nerves and are innervated by them. The lateral part consists of longer fascicles which follow a dorsocranial course and attach to the ventral tubercles of preceding vertebrae as well as to the wing of the atlas. All ventral intertransverse muscles are innervated by the ventral rami of cervical spinal nerves.     

Myelopathy and Reactive Microgliosis and Astrogliosis in Equine Back Pain

Equine chronic back pain (CBP) has been linked to different pathologic processes, which directly or indirectly involve spinal structures. Thus, making diagnosis and management very challenging with most horses with the condition recommended for early retirement from athletic activity. This study described the spinal cord lesions and the development of reactive microgliosis and astrocytosis in the spinal cords of horse with CBP. Thoracolumbar spinal cord segments from three horses euthanized because of unresolved CBP were dissected and grossly and histopathologically examined. The expression of activated microglia and astrocytes were demonstrated immunohistochemically using polyclonal rabbit anti-Iba-1 and anti-glial fibrillary acidic protein antibodies, respectively. All horses had radiological evidence of varying degrees of kissing spine involving six to nine vertebrae with the majority of the lesions graded between 2 and 5. Grossly, there was myelomalacia with intramedullary hemorrhages. The gray matters of the spinal cords were characterized by hemorrhagic malacic lesions with medullary disintegration. Reactive microgliosis and astrocytosis were evident in the spinal dorsal horns. White matter lesions include axonal swollen and/or loss, satellitosis, and varying degrees of dilation of myelin sheaths with some containing macrophages. In conclusion, the presence of reactive microgliosis and astrogliosis in the spinal dorsal horn indicates that they are possible precipitating factors in the development of equine CBP.     

Fecal incontinence and spinal cord abnormalities in seven dogs

Seven dogs with fecal incontinence and abnormal gaits were evaluated. Fecal incontinence was characterized as defecation of normal stools without posturing. Duration of clinical signs prior to evaluation ranged from 5 months to 3 years. Five dogs had upper motor neuron (UMN) paraparesis, and 2 dogs had UMN tetraparesis. With magnetic resonance imaging, spinal cord abnormalities primarily involving the dorsal aspect of the spinal cord were identified in all dogs. Five dogs had focal abnormalities, and 2 dogs had diffuse abnormalities of the spinal cord. Of the dogs with focal spinal cord lesions, 4 had cystic spinal cord abnormalities and 1 had a meningioma. Surgery was performed on all dogs with focal lesions; 4 of the 5 dogs had resolution of fecal incontinence after surgery. Results in these dogs suggest that fecal incontinence can be associated with spinal cord abnormalities and, depending on the characteristics of the lesion, can resolve after surgical treatment of the abnormality.     

Magnetic resonance imaging diagnosis of intervertebral disc disease and myelomalacia in an American black bear (Ursus americanus)

A 23-yr-old black bear (Ursus americanus) was examined because of paralysis of unknown duration. The precise onset of clinical signs was unknown as a result of seasonal torpor. The bear was immobilized and transported to a university veterinary teaching hospital for further evaluation and treatment. Radiography revealed increased mineral opacity and ventral bridging across vertebral segments T8-11. Magnetic resonance imaging demonstrated dorsal and ventral compression of the spinal cord at T8-9. Given the bear's advanced age, the unknown duration of spinal cord compression, unknown presence of deep pain perception, and thus an unknown prognosis for surgical success, euthanasia was elected. Postmortem examination revealed severe spondylosis deformans from T7 to L3 and dorsal extradural extruded disc material in the area of T8-9. Histopathology demonstrated the dorsal horns of the spinal cord at T9 were replaced by foamy macrophages extending into the dorsal and lateral funiculi of the white matter compatible with focal, severe, chronic myelomalacia. This is the first report of intervertebral disc disease and myelomalacia diagnosed using MRI in a large carnivore.     

Spinal trauma. Pathophysiology and management of traumatic spinal injuries.

Spinal trauma can originate from internal or external sources. Injuries to the spinal cord can be classified as either concussive or compressive and concussive. The pathophysiologic events surrounding spinal cord injury include the primary injury (compression, concussion) and numerous secondary injury mechanisms (vascular, biochemical, electrolyte), which are mediated by excessive oxygen free radicles, neurotransmitter and electrolyte alterations in cell membrane permeability, excitotoxic amino acids, and various other biochemical factors that collectively result in reduced SCBF, ischemia, and eventual necrosis of the gray and white matter. Management of acute spinal cord injuries includes the use of a high-dose corticosteroid regimen within the initial 8 hours after trauma. Sodium prednisolone and methylprednisolone, at recommended doses, act as oxygen radical scavengers and are anti-inflammatory. Additional considerations are the stability of the vertebral column, other conditions associated with trauma (i.e., pneumothorax), and the presence or absence of spinal cord compression, which may warrant surgical therapy. Vertebral fractures or luxations can occur in any area of the spine but most commonly occur at the junction of mobile and immobile segments. Dorsal and dorsolateral surgical approaches are applicable to the lumbosacral and thoracolumbar spine and dorsal and ventral approaches to the cervical spine. Indications for surgical intervention include spinal cord compression and vertebral instability. Instability can be determined from the type of fracture, how many of the three compartments of the vertebrae are disrupted, and on occasion, by carefully positioned stress studies of fluoroscopy. Decompression (dorsal laminectomy, hemilaminectomy, or ventral cervical slot) is employed when compression of the spinal cord exists. The hemilaminectomy (unilateral or bilateral) causes less instability than dorsal laminectomy and therefore should be used when practical. The preferred approach for atlantoaxial subluxation is ventral, and the cross pinning, vertebral fusion technique is used for stabilization. Fracture luxations of C-2 are repaired with small plates on the ventral vertebral body. The thoracic and upper lumbar spine is stabilized with dorsal fixation techniques or combined dorsal spinal plate/vertebral body plate fixation. Several methods of fixation can be used with lower lumbar or lumbosacral fractures, including the modified segmental technique and the combined dorsal spinal plate/Kirschner-Ehmer technique.     

Caprine encephalomyelomalacia

Six cases of encephalomyelomalacia in dairy goats 3 1/2 to four months of age are described. Neurologic signs had an abrupt onset and passed rapidly from ataxia to paralysis. All goats were killed after six to ten days and had spinal cord and brain stem lesions--always more extensive and severe in the cord. The bilaterally symmetrical necrotic lesions were restricted to the ventral and intermediate gray substance in the cord and to certain brain stem nuclei. The spinal cord enlargements were affected especially.     

Subdural injection of contrast medium as a complication of myelography

In a retrospective evaluation of 654 canine and feline myelograms, 58 were found to have been complicated by injection of the contrast medium into the subdural space. The medium was present predominantly dorsal to the spinal cord, with a sharp dorsal border and an undulating ventral border. Confirmation that this myelographic appearance was due to subdural localisation was achieved using fresh cadavers injected with contrast medium labelled with Indian ink. It was further showed that the dorsal accumulation of contrast medium was due to the denticulate ligaments which restricted the ventral extension of the contrast medium.     

Pathological features of ganglioradiculitis (sensory neuropathy) in two dogs

Canine ganglioradiculitis (sensory neuropathy) was examined pathologically in two dogs (dog Nos. 1 and 2). The affected dogs had 1 and 2 years clinical courses from the onset, respectively. As common clinical signs, both cases showed progressive ataxia, difficulty in prehending food, visual deficit, and several sensory abnormalities. Gross observation after tissue fixation revealed whitish discoloration in the dorsal column of the spinal cords. The histological lesions were mainly distributed in the spinal dorsal roots, ganglions, and dorsal columns. In the spinal dorsal roots and ganglions, there were striking myelin loss, mild infiltration of mononuclear cells, and proliferation of small spindle cells. In the dorsal funiculus, there were moderate to severe diffuse myelin-loss and axonal degeneration. Immunohistochemistry for substance P (SP) revealed marked reduction of SP-immunopositive granules in the spinal substantia gelatinosa of affected dogs. By immunohistochemistry, CD3-positive cells were observed in the dorsal roots of dog No. 2, while CD3-positive cells were rare in those of dog No. 1. In the spinal ganglion of dog No. 1 there were many CD3- and MHC class II-positive cells. By indirect immunofluorescence assay using sera from affected dogs, no autoantibodies against canine nerve tissues were detected. The clinicopathological features of the present cases are almost consistent with those in previous reports of canine sensory neuropathies, while the etiology remains unclear.     

Thoracolumbar dorsolateral laminectomy with osteotomy of the spinous process in fourteen dogs

Objective— To describe outcome after an alternative unilateral approach to the thoracolumbar spine for dorsal laminectomy.
Study Design— Retrospective clinical study.
Animals— Dogs (n=14) with thoracolumbar spinal cord compression.
Methods— Thoracolumbar spinal cord compression was lateral (6 dogs), dorsal (4), and dorsolateral (4) caused by subarachnoid (7) and synovial cysts (2) and intradural-extramedullary neoplasia (5). All dogs were treated by dorsal laminectomy with osteotomy of the spinous process using a unilateral paramedian approach. The contralateral paraspinal muscles were not stripped from the spinous process and the osteoligamentous complexes were preserved. Retraction of the spinous process and muscles to the contralateral side resulted in complete visualization of the dorsal vertebral arch thereby allowing dorsal laminectomy to be performed.
Results— No technique complications occurred. Approximately 75% exposure of the spinal cord (dorsal and lateral compartments) was achieved providing adequate visualization and treatment of the lesions. Transient deterioration of neurologic state occurred in 5 dogs because of extensive spinal cord manipulation. At long-term follow-up, 6 dogs were normal, 6 had clinical improvement, and 2 were unchanged.
Conclusion— Dorsal laminectomy after osteotomy and retraction of the spinous process may be considered in canine patients with dorsal, dorsolateral, or lateral compression to facilitate adequate decompression of the spinal cord.
Clinical Significance— This surgical technique offers an alternative approach to the thoracolumbar spine and spinal cord by a modified dorsal laminectomy that preserves the paraspinal muscle integrity on the contralateral side.     

Acute intervertebral disc extrusion in a cat: clinical and MRI findings

A 5 year old, neutered male, domestic shorthaired cat had acute left hemiparesis and Horner's syndrome. Magnetic resonance imaging (MRI) revealed a loss of the normal signal from the nucleus pulposus of the intervertebral disc at C3/4, narrowing of the ventral subarachnoid space and slight dorsal displacement of the spinal cord and a focal hyperintense lesion affecting the left side of the spinal cord at the same level. The presumptive diagnosis was focal spinal cord oedema associated with intervertebral disc extrusion. A traumatic aetiology was suspected. The cat was treated conservatively and improved gradually over a period of 6 months.     

Anatomical study of blood supply to the cervical spinal cord in the guinea pig

The aim of this study was to describe the arterial arrangement of the cervical spinal cord in the guinea pig. The study was carried out on 20 adult English self guinea pigs using corrosion and dissection technique. Batson's corrosion casting kit no. 17^© was used as a casting medium. The origin of the ventral spinal artery from the left vertebral artery was found on average in 35% of the cases and from the right vertebral artery on average in 40% of the cases. The ventral spinal artery with origin from the anastomosis of two medial branches was found on average in 25% of the cases. The presence of ventral radicular branches of rami spinales entering the ventral spinal artery in the cervical region was observed in 42% of the cases on the right side and in 58% of the cases on the left side. The presence of dorsal radicular branches of rami spinales that reached the spinal cord was observed in 63% of the cases on the left side and in 37% of the cases on the right side. The number of radicular branches supplying the spinal cord is greater in guinea pig than in humans.     

Disc extrusion in a Rottweiler dog with caudal cervical spondylomyelopathy after failure of intervertebral distraction/stabilisation

A Rottweiler dog was presented with an 8 week history of hindlimb ataxia. Neurological examination localised the lesion to the cervical spinal cord. Myelography demonstrated dynamic compressive lesions at C5-6 and C6-7 consistent with a diagnosis of caudal cervical spondylomyelopathy. Distraction/stabilisation of both discs was performed using interbody polymethyl methacrylate. Both implants subsequently failed leading to extrusion of the remaining dorsal annulus fibrosus of the C5-6 intervertebral disc and nonambulatory tetraparesis. A ventral slot combined with distraction/stabilisation using screws and polymethyl methacrylate was performed and resulted in nearly full neurological recovery.     

Spinal Nerve Root Origin of the Median, Ulnar and Musculocutaneous Nerves and their Muscle Nerve Branches to the Canine Forelimb

The contribution individual ventral spinal nerve roots made to the canine median nerve, ulnar nerve, musculocutaneous nerve, and their muscle nerve branches was determined electrophysiologically. Each spinal nerve root was sequentially stimulated. Utilizing quantitative signal averaging techniques, the evoked potential was measured at each tested peripheral nerve. Evoked potential to the median nerve originated from the seventh cervical spinal root (C7) through the second thoracic spinal root (T2) with most input from C8 and T1. The ulnar nerve received evoked potential from C7-T2. Although T1 provided the major input to both the median and ulnar nerves, the relative contribution of T1 was greater in the ulnar nerve. The musculocutaneous nerve received input from ventral spinal roots C6-T1 with C6 and C7 providing most of the evoked potential. The ventral spinal roots which supplied the bulk of the evoked potential to a particular muscle nerve were consistent between individual dogs. Variation of evoked potential input was greatest from spinal roots which supplied less than 10% of the total potential.