Experience of the operative treatment of dogs at displacements of intervertebral discs

Abstract

Relevance. Fractures of the spine, subluxations and dislocations, herniated discs can lead to the development of acute tetraparesis or tetraplegia as a result of bleeding and compression of the thoracolumbar spinal cord [5]. In addition to direct traumatic damage to the spinal cord, secondary neurotoxic processes develop with the formation of free radicals containing oxygen, and a cycle of progressive destruction of the spinal cord is started, which lasts for 48 hours. If bone fragments fall into the spinal canal with injury, then the spinal cord is decompressed by the dorsal laminectomy method. In case of trauma, arteries of the spine are damaged, as a result of which the bodies of neurons and nerve roots are additionally damaged, and their restoration is slow and may be incomplete.

         Violation of limb functions often occurs with degenerative diseases of intervertebral discs (DDID). The most common cause of paraplegia or acute paraparesis in dogs is type I DDID according to Hansen's classification. It is also called "soft hernia", when the pulpous nucleus of the intervertebral disc breaks through the fibrous ring and causes contusion and compression of the spinal cord [1, 5]. Since the size of the spinal canal in the lumbar region is insignificant in comparison with the diameter of the spinal cord, extrusion of the disk causes more severe damage to the spinal cord than in the cervical region [5]. The protrusion of the intervertebral disc squeezes the spinal cord, as it is surrounded by bone tissue and can not move to the side. Elevated blood pressure prevents circulation of blood in the spinal cord and leads to fluid stagnation and edema formation. As a result, intradural pressure increases, blood circulation worsens, myelomalacia develop [9].

         For operative treatment of extrusion of the intervertebral disc substance in the thoracic or lumbar region, hemilaminectomy is performed [1, 3]. With mini-hemilaminectomy resection of a part of the arch of adjacent vertebrae is performed with subsequent expansion of the intervertebral foramen without the removal of articular processes of the vertebrae [3, 4]. As a result, the risk of developing instability is significantly less than with hemilaminectomy [7]. Therefore, recently there are recommendations for the actual mini-hemilaminectomy itself, as a less invasive surgical intervention [4].

         Foraminectomy is surgical manipulation, which makes it possible to access the site of articular facets of the vertebrae and to intervene at the level of the intervertebral foramen in case of compression of the spinal cord spinal cord.

         Radicular syndrome, which occurs as a result of compression of nerves in the region of C6-T2 or L4-S2 in the lateral displacement of the disc is characterized by severe soreness in the lumbar region [5]. The protrusion of the disc with the formation of a hernia can arise from one side of the dorsal elongated ligament, forms the bottom of the spinal canal. As a consequence, the lesion of one of the limbs may develop more than the other. As a result, the irritation of the nerve endings is manifested by the violation of the support of the diseased limb in a standing position and by considerable morbidity, which causes lameness during movement.

The aim of the study is early and timely diagnosis of degenerative changes in intervertebral discs in dogs of various breeds with the definition of the optimal method of providing surgical assistance for decompression of the spinal cord.

Materials and methods of research. Statistical, radiographic. To study dogs used: intravenous catheters Braun 18-20 size; symptomatic drugs (antihistamines, respiratory analeptics, loop diuretics); spinal needles, Spinosan R 40 mm long; solution of radiopaque Omnipak with concentrations of iodine 300 mg/ml; neurological set of instruments for surgical intervention; retractors; The elevators Hauman and Gelpi for spreading the muscles; Cutters of Carrison; Freer dissector for raising paravertebral muscles; high-speed cutter with a speed of 90,000 revolutions with a wetting system and a pedal drive; portable aspirator New Askir 30 from cannula for aspiration; electrosurgical apparatus HEACO ZEUS 200 (mono- and bipolar) MRI device with a power of 0.3T; X-ray apparatus ВАТЕЛ-1.

         The object of the study were dogs (n = 6) of different ages and breeds:

2 short-haired taxis of 4 and 6 years; 1 pug for 7 years; 3 French bulldogs 4, 6 and 8 years old.

Results of the study and their discussion.  Based on the results of the study, in 3 dogs, type I DDID was established according to Hansen with ventrolateral placement of the hernia in the intervertebral discs, in another group of animals, type I Hansen DDID was identified with dorsolateral placement of the hernia and radicular syndrome, which led to severe pain syndrome. Mini-hemilaminectomy was performed with the help of lateral or dorso-lateral access to the spine with a lateral or semi-lateral position of the dog [3]. With dorso-lateral access, the longest muscle was separated from the divided lumbar muscles in the craniomedial direction, where the tendon of the long muscle joins the additional processes of the vertebrae. Sections of the intervertebral disc and vertebrae were separated from the muscles and dissected the tendon of the longest muscle. With the help of the cutter, an additional vertebra process was removed, followed by a resection of the vertebral arches to open the orifice with a size of 1/2-2/3 the length of each vertebra. To stop bleeding from the venous sinuses or vertebral artery, a bipolar coagulator with the following characteristics was used: bipolar coagulation - 80 W/ 100 Ω; bipolar cutting - 80 W/200 Ω. After the surgical intervention, the dogs were restricted in movement for 3-4 weeks, depending on the severity of the neurological deficit. All animals received a course of methylprednisolone sodium succinate (MPSS) at 30 mg/kg. Two hours after the first administration, MPSS was administered at a dose of 15 mg/kg and repeated every 6 hours for 24-48 hours in the absence of independent limb movements.

Conclusions and prospects.

1. Early diagnosis and prompt intervention by the method of mini-hemilaminectomy or foraminectomy in the first 24-48 hours with subsequent prescription of symptomatic drugs in the postoperative period and maintenance in an enclosure with limited movements up to 3 weeks provided the best clinical result.

2. To establish the presence of a herniated pulpous nucleus intervertebral disc, damage the integrity of the spinal cord, it is recommended that contrast myelography and MRI diagnosis. These methods best determine the location of the spinal cord in the vertebral canal. In particular, MRI can well visualize both extrusion and protrusion of the intervertebral disc, compression fractures of the vertebral bodies, various degenerative changes in the form of discosponse, as well as stenosis of the spinal canal, etc.

3. For all operated animals, a postoperative course of rehabilitation with limited movement and maintenance in the aviary up to 2-3 weeks and the administration of glucocorticosteroid agents (methylprednisolone sodium succinate) or the introduction of veterinary drugs from the group of nonsteroidal anti-inflammatory drugs with symptomatic support of organs and systems is recommended.