Presence of residual material following mini-hemilaminectomy in dogs with thoracolumbar intervertebral disc extrusion.

Presence of residual material following mini-hemilaminectomy in dogs (n = 9) with spontaneous thoracolumbar intervertebral disc extrusion was prospectively investigated. Volume of extruded disc material within the vertebral canal and the proportion of residual material were determined using pre- and post-operative magnetic resonance imaging. The degree of spinal cord compression, proportion of extradural material considered hemorrhage, and invasion of the articular facets were also determined. Residual material was identified in 44% of the mini-hemilaminectomies. The median percentage of residual material calculated was 7.7% of the preoperative volume. No observed effect of surgical side or site, proportion of extradural material considered hemorrhage, patient weight, and duration of clinical signs was detected.

Présence de matières résiduelles après une mini-hémilaminectomie chez des chiens avec une extrusion d'un disque intervertébral thoracolombaire. La présence de matières résiduelles après une mini-hémilaminectomie chez les chiens (n = 9) avec une extrusion spontanée d'un disque intervertébral thoracolombaire a fait l'objet d'une étude prospective. Le volume de fragment discal exclu dans le canal vertébral et la proportion de matières résiduelles ont été déterminés en utilisant une imagerie par résonance magnétique avant et après l'opération. Le degré de compression de la moelle épinière, la proportion de matières extradurales considérées comme de l'hémorragie et l'invasion des facettes articulaires ont aussi été déterminés. Les matières résiduelles ont été identifiées dans 44 % des mini-hémilaminectomies. Le pourcentage médian des matières résiduelles calculé s'établissait à 7,7 % du volume préopératoire. Aucun effet observé pour le côté ou le site chirurgical, la proportion des matières résiduelles considérées comme de l'hémorragie, le poids du patient et la durée des signes cliniques n'a été détecté.(Traduit par Isabelle Vallières).

Comparison of the access window created by hemilaminectomy and mini-hemilaminectomy in the thoracolumbar vertebral canal using computed tomography.

Hemilaminectomy and mini-hemilaminectomy were performed on opposite sides of the spine at T11-T12, T13-L1, and L2-L3 in 11 canine cadavers in order to report differences in the access provided to the thoracolumbar vertebral canal. Measurements of the vertebral canal height, defect height, and dorsal and ventral remnants of the vertebral arch were obtained after computed tomography. A median of 7% to 20% of the vertebral canal height was not removed dorsally after mini-hemilaminectomy compared to 1% to 2% in hemilaminectomy. Thirteen to 25% of the vertebral canal height was left ventrally in mini-hemilaminectomy and 11% to 27% in hemilaminectomy. Potential for a restricted exposure of thoracolumbar lesions should be considered if lesions are located in the ventral 11% to 27% vertebral canal height when performing either procedure or in the dorsal 7% to 20% of the canal height when performing a mini-hemilaminectomy.

Comparaison, à l'aide de tomodensitométrie, de la fenêtre d'accès créée par une hémilaminectomie et une mini-hémilaminectomie dans le canal vertébral thoracolombaire. Une hémilaminectomie et une mini-hémilaminectomie ont été réalisées sur les côtés opposés de la colonne vertébrale à T11­T12, à T13-L1 et à L2­L3 sur 11 cadavres canins afin de signaler les différences de l'accès fourni au canal vertébral thoracolombaire. Les mesures de la hauteur du canal vertébral et des vestiges dorsaux et ventraux de l'arc vertébral ont été obtenues après une tomodensitométrie. Une médiane de 7 % à 20 % de la hauteur du canal vertébral n'a pas été enlevée dorsalement après une mini-hémilaminectomie comparativement à 1 % ou 2 % pour une hémilaminectomie. De 13 % à 25 % de la hauteur du canal vertébral a été laissée ventralement dans la mini-hémilaminectomie et de 11 % à 27 % dans l'hémilaminectomie. Le potentiel d'une exposition restreinte des lésions thoracolombaires devrait être considéré si les lésions sont situées dans le 11 % à 27 % de la portion ventrale de la hauteur du canal vertébral lors de la réalisation des deux interventions ou dans le 7 % à 20 % de la portion dorsale de la hauteur du canal lors de la réalisation d'une mini-hémilaminectomie.(Traduit par Isabelle Vallières).

Feasibility of percutaneous catheterization and embolization of the thoracic duct in dogs.

OBJECTIVE: To develop and determine the feasibility of a novel minimally invasive technique for percutaneous catheterization and embolization of the thoracic duct (PCETD) in dogs and to determine thoricic duct TD pressure at rest and during short-term balloon occlusion of the cranial vena cava (CrVC). ANIMALS: Fifteen 7- to 11-month-old healthy mixed-breed dogs. PROCEDURES: Efferent intestinal lymphangiography was performed, and the cisterna chyli was punctured with a trochar needle percutaneously under fluoroscopic guidance. When access was successful, a guide wire was directed into the TD through the needle and a vascular access sheath was advanced over the guide wire. Thoracic duct pressure was measured at rest and during acute balloon occlusion of the CrVC. The TD was then embolized cranial to the diaphragm with a combination of microcoils and cyanoacrylate or ethylene vinyl alcohol. RESULTS: Successful puncture of the cisterna chyli with advancement of a wire into the TD was possible in 9 of 15 dogs, but successful catheterization was possible in only 5 of 9 dogs. Acute balloon occlusion of the CrVC led to a substantial TD pressure increase in 4 of 4 dogs, and embolization of the TD was successful in 4 of 4 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: PCETD can successfully be performed in healthy dogs; however, this minimally invasive technique cannot currently be recommended for routine treatment of chylothorax, in part because of the technically demanding nature of the procedure. An increase in jugular venous pressure led to an increase in TD pressure, potentially predisposing some dogs to developing chylothorax.

Determination of the prevalence and severity of metacarpophalangeal joint osteoarthritis in Thoroughbred racehorses via quantitative macroscopic evaluation.

OBJECTIVE: To determine the prevalence and severity of osteoarthritis in the metacarpophalangeal joints of Thoroughbred racehorses via development and validation of a quantitative macroscopic evaluation system. SAMPLE POPULATION: Metacarpophalangeal joints from 50 Thoroughbred racehorses. PROCEDURES: Joints were collected from horses that died or were euthanized within 60 days of racing. Metacarpophalangeal joints were assessed for osteoarthritic degeneration by use of macroscopic and histologic scoring systems, polarized light microscopy, and cartilage biochemical analysis. The global macroscopic score for the entire metacarpophalangeal joint was based on factors that reflected the size and severity of lesions as well as the involvement of weight-bearing surfaces. RESULTS: One-third of all 2- and 3-year-old horses had partial-or full-thickness cartilage lesions and osteoarthritis. Osteoarthritis severity increased until age 6 in this population. Significant correlations were found between macroscopic grade and age, cause of death, glycosaminoglycan depletion, and loss of superficial cartilage zone polarized light intensity. CONCLUSIONS AND CLINICAL RELEVANCE: The macroscopic system devised for this study had good correlations with quantitative methods. Two-and 3-year-old horses had full-thickness cartilage lesions that may have been career limiting. Year-to-year attrition and a small population of older horses may have led to underestimation of the prevalence of osteoarthritis in older horses. The macroscopic scoring system was reliable when used by nonexpert and expert users.