Changes in Third Carpal Bone Articular Cartilage After Synovectomy in Normal and Inflamed Joints

Objective —To determine if arthroscopic synovectomy in normal and inflamed joints had temporal or site-related effects on articular cartilage.
Study Design —Alterations in equine third carpal bone articular cartilage were studied at two time periods: groups 1 and 2 (6 weeks) and groups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) and inflamed carpi (groups 1 and 3).
Animal Population —16 carpi from eight horses.
Methods —Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radiolabeling, proteoglycan (PG) extraction, chromatography, electrophoresis, and indentation testing.
Results —Synovectomy in inflamed joints produced the greatest concentration of newly synthesized PG in articular cartilage by 2 weeks. Synovectomy in normal joints produced significantly greater newly synthesized PG in articular cartilage by 6 weeks. Endogenous PG was only significantly greater in inflamed joints after 6 weeks. Dorsal sites had greater newly synthesized and endogenous PG in some groups. Chromatographic profiles of newly synthesized PG demonstrated early and late PG peaks. Electrophoresis of late PG peak showed a toluidine blue-positive band that comigrated with human A1D1 PG monomer in the two groups with the most newly synthesized PG. This band was reactive with monoclonal antibody 1C6 specific for the hyaluronic acid-binding region of aggrecan. For the material properties evaluated, only Poisson's ratio was significantly decreased between groups as a function of time (6 weeks < 2 weeks), and this was most pronounced in the thicker dorsal sites.
Conclusions —Synovectomy in inflamed joints produced site-specific, significantly greater responses in articular cartilage as compared with synovectomy in normal joints.
Clinical Relevance —Synovectomy may not be beneficial to the articular cartilage in inflamed joints.     

Management of a keratoma in a horse: A case report

An 8-year-old Thoroughbred gelding presented with chronic intermittent lameness of the left forelimb. Keratoma was diagnosed based on history, clinical signs and the radiographic evidence of a radiolucent concavity of the third phalanx. The keratoma was removed by hoof wall resection and the foot was immobilized using a bar shoe with clips and a dorsal hoof wall plate positioned across the hoof wall defect. The hoof wall defect was completely filled with new hoof wall by 9 months postoperatively. The horse returned to normal athletic function and is performing successfully 18 months later.     

An Ex Vivo Biomechanical Study Comparing Strength Characteristics of a New Technique with the Three‐Loop Pulley for Equine Tenorrhaphy

Objective: To test single cycle to failure tensile strength characteristics of 6 suture material–pattern combinations in equine superficial digital flexor (SDF) tenorrhaphy, specifically to compare a 10‐strand modification of the Savage core suture technique with the 3‐loop pulley technique. Study Design: Ex vivo mechanical experiment comparing 3 different suture patterns with 2 different materials. Sample Population: Forelimb and hindlimb SDF tendons (n=48) harvested from adult Thoroughbred and Standardbred horses of mixed age and gender. Methods: Six suture material–pattern combinations were evaluated: (1) 10‐strand Savage, size 2 polydioxanone (PDS); (2) 10‐strand Savage, size 2 polyglactin 910 (PG910); (3) 10‐strand Savage, size 2 PDS with Lin‐locking epitenon suture, size 2–0 PDS; (4) 10‐strand Savage size 2 PG910 with Lin‐locking epitenon suture, size 2–0 PDS; (5) 3‐loop pulley, size 2 PDS; and (6) 3‐loop pulley, size 2 PG910. Maximum load at failure (N), gap at failure (mm), and mode of failure (suture breakage or pull through) were evaluated for each of the 6 suture material–pattern combinations and underwent statistical analysis to determine significance of differences and interactions of the measured data. Results: The 10‐strand Savage technique failed at a mean load of 872 N (804–939, 95% CI). The 10‐strand Savage with Lin‐locking failed at a significantly greater mean load of 998 N (930–1065, 95% CI). The 3‐loop pulley pattern failed with a mean load of 337 N (270–405, 95% CI). There were significant interactions between the technique and suture material used. Conclusion: The 10‐strand Savage technique for repair of transected cadaver SDF tendons has superior strength characteristics with or without the epitenon suture when compared to the 3‐loop pulley. Suture material and pattern interactions were observed with PG 910 conferring higher strength for the 10‐strand Savage whereas PDS did so for the 3‐loop pulley.     

Diagnostic Predictors of Complications and Survival after Renal Transplantation in Cats

OBJECTIVE: To identify preoperative diagnostic results that predict postoperative complications and survival in feline renal-transplant recipients. STUDY DESIGN: Retrospective clinical study. ANIMALS: Sixty-one feline renal allograft recipients. METHODS: Medical records for 61 consecutive cats that underwent renal allograft transplantation between January 1, 1996, and December 1, 1999, were reviewed. Age, diagnosis, body weight, body condition score, preoperative medical treatment, systolic blood pressure, packed cell volume, biochemical parameters at admission and at the time of surgery, postoperative complications, and postoperative survival were recorded. Associations of preoperative data with the occurrence of postoperative complications were determined using logistic regression. Postoperative survival was graphed using a Kaplan-Meier cumulative-survival plot. Associations of covariates with postoperative survival were analyzed using Cox proportional hazards analysis. RESULTS: Two parameters were significantly associated with occurrence of postoperative central nervous system (CNS) disorders: blood urea nitrogen concentration (odds ratio = 1.083; 95% CI = 1.018 to 1.148) and serum creatinine concentration (odds ratio = 1.8; 95% CI = 1.413 to 2.187) at the time of surgery. Postoperative survival 6 months after transplantation was 59%, though 3-year survival remained at 42%. Of all covariates investigated, only recipient age (relative hazard = 1.183; 95% CI = 1.039 to 1.334) was significantly associated with survival. CONCLUSION AND CLINICAL RELEVANCE: Standard measures of preoperative renal dysfunction do not predict postoperative survival in cats after renal transplantation, although an increase in the degree of preoperative azotemia is associated with an increased risk of CNS disorders after surgery. Increased recipient age is associated with decreased survival after renal transplantation.     

Distal Interphalangeal Joint Arthrodesis in Seven Cattle Using the Acutrak Plus Screw

Objectives— To report a technique for arthrodesis of the distal interphalangeal joint (DIPJ) with two 6.5 mm Acutrak Plus (AP) compression screws from a solar approach and outcome in 7 cattle.
Study Design— Case series.
Animals— Cattle (n=7) with DIPJ arthritis.
Methods— Retrieved data from medical records of cattle that had undergone DIPJ arthrodesis using 2 AP screws via a solar approach were signalment, history, clinical signs, preoperative blood work, preoperative radiographs, complications, postoperative radiographs, and postoperative lameness evaluation. Outcomes, assessed by owner interview 6–26 months after surgery, were classified as excellent, good, or poor.
Results— Fusion of the DIPJ was evident by 6 months. All cattle returned to full function with minimal lameness and normal appearance to the distal aspect of the limb. Four thoracic limbs and 3 pelvic limbs were affected; 3 medial and 4 lateral claws. Complications included moderate lameness associated with implants (n=2) that resolved after screw removal.
Clinical Relevance— Use of the AP screw system in cattle is an excellent option for DIPJ arthrodesis with minimal postoperative morbidity and excellent return to function.     

Comparison of Three Drilling Techniques for Carpometacarpal Joint Arthrodesis in Horses

Objective: To evaluate 3 drilling techniques for arthrodesis of the equine carpometacarpal (CMC) joint. Study Design: Experimental study. Sample Population: Cadaveric equine forelimbs (n=15). Methods: Limbs were divided into 3 groups (5 limbs each) to evaluate 3 drilling techniques: (1) use of a 4.5 mm drill bit inserted into the joint through 4 entry points and moved in a fanning motion; (2) a 5.5 mm drill bit inserted through 2 entry points to create 3 nonfanned drill tracts (3 drill technique); and (3) a 4.5 mm drill bit used in a 3 drill technique. The CMC joint was disarticulated after drilling, and cartilage and subchondral bone damage evaluated visually and by gross and microradiographic examination using planimetry. Results: Technique 1 produced significantly more damage of the proximal surface, but significantly less to the subchondral bone of the distal surface. Technique 1 produced the most damage to both the articular cartilage and subchondral bone of the total CMC joint than either of the 3 drill tract techniques; however, the difference between techniques 1 and 2 was not significant. Damage from technique 3 was significantly less than that with techniques 1 or 2. Conclusions: Techniques 1 and 2 produced the most cartilage and subchondral bone damage with technique 2 changes more equally distributed between proximal and distal joint surfaces. Clinical Relevance: Technique 1 (fanning) and 2 (5.5 mm 3 drill tracts) may be preferable to achieve arthrodesis of the CMC joint. Morbidity and efficacy of these arthrodesis techniques need to be evaluated in vivo.     

Cardiovascular Effects After Epidural Injection of Xylazine in Isoflurane-Anesthetized Dogs

The cardiovascular effects following epidural injection of xylazine or isotonic saline during isoflurane anesthesia were assessed in six healthy dogs. Dogs were anesthetized with isoflurane in O₂ and maintained at 2.0% end-tidal concentration. Ventilation was controlled to maintain PaCO₂ at 35 to 45 mm Hg. The dorsal pedal artery was cannulated for measurement of arterial blood pressure (AP)(systolic AP, mean AP, diastolic AP) and for blood sample collection. Arterial pH and blood gas tensions (PaO₂ and PaCO₂) were determined. Cardiac output was measured by thermodilution. The electrocardiogram (ECG), heart rate (HR), core body temperature, central venous pressure (CVP), mean pulmonary AP, and end-tidal isoflurane concentration (ETISO) and CO₂ tension (ETCO₂) were monitored. Systemic vascular resistance (SVR), arterial HCO₂ concentration, base balance, and cardiac index (CI) were calculated. After baseline measurements were taken, either xylazine (0.2 mg/kg) in 5 mL isotonic saline or 5 mL of isotonic saline was injected into the lumbosacral epidural space. Data were then recorded at 5, 15, 30, 45, 60, 75, 90, 105, and 120 minutes after epidural injection. Data were analyzed by two-way analysis of variance (ANOVA) for repeated measures. When significant differences were encountered, mean values were compared using Bonferroni's test. The level of significance was set at P <.05. Mean values for diastolic AP decreased at 90 and 120 minutes compared with the mean value at 15 minutes after epidural injection of xylazine. No differences were detected at any time or between treatments for HR, systolic AP, mean AP, CVP, CI, SVR, mean pulmonary AP, temperature, ETCO₂, ETISO, arterial pH, PaCO₂, PaO₂, plasma bicarbonate concentration, or base balance. Results of this study indicate that epidural injection of xylazine (0.2 mg/kg) is associated with minimal cardiovascular side effects during isoflurane anesthesia in mechanically ventilated dogs.     

Laser-Doppler Measurements of Spinal Cord Blood Flow Changes During Hemilaminectomy in Chondrodystrophic Dogs with Disk Extrusion

Objectives— (1) To assess spinal cord blood flow (SCBF) during surgical treatment of disk extrusion in dogs and (2) to investigate associations between SCBF, clinical signs, presurgical MRI images, and 24-hour surgical outcome.
Study Design— Cohort study.
Animals— Chondrodystrophic dogs with thoracolumbar disk extrusion (n=12).
Methods— Diagnosis was based on clinical signs and MRI findings, and confirmed at surgery. Regional SCBF was measured intraoperatively by laser-Doppler flowmetry before, immediately after surgical spinal cord decompression, and after 15 minutes of lavaging the lesion. Care was taken to ensure a standardized surgical procedure to minimize factors that could influence measurement readings.
Results— A significant increase in intraoperative SCBF was found in all dogs (Wilcoxon's signed-rank test; P =.05) immediately after spinal cord decompression and after 15 minutes. Changes in SCBF were not associated with duration of clinical signs; initial or 24-hour neurologic status; or degree of spinal cord compression assessed by MRI.
Conclusion— SCBF increases immediately after spinal cord decompression in dogs with disk herniation; however, increased SCBF was not associated with a diminished 24-hour neurologic status.
Clinical Relevance— An increase in SCBF does not appear to be either associated with the degree of spinal cord compression or of a magnitude sufficient to outweigh the benefit of surgical decompression by resulting in clinically relevant changes in 24-hour outcome.     

Right Dorsal Colon Resection and Bypass for Treatment of Right Dorsal Colitis in a Horse

Objective: To describe a novel surgical technique for management of right dorsal colitis in the horse. Study Design: Clinical report. Animals: 14‐year‐old Warmblood gelding. Methods: The horse was referred for treatment of a stromal abscess and signs of right dorsal colitis. Plasma chemistry revealed marked hypoproteinemia. Abdominal ultrasonographic examination showed a thickened right dorsal colon (RDC). Medical treatment was unsuccessful. With the horse in left lateral recumbency under general anesthesia, an approach to the right side of the abdomen through a 16th rib resection was made. The thoracic cavity was entered during the approach. Surgical resection of the RDC and side‐to‐side anastomosis of the diaphragmatic flexure to the small colon (bypass) was performed. The thoracic cavity was closed by attaching the diaphragm to the body wall and air was removed at the completion of surgery. Results: Resection of the RDC and bypass of the resected area was successfully performed. The colic signs and hypoproteinemia resolved. Complications of surgery included a deep surgical site infection with development of a large intrathoracic abscess. The abscess was managed with drainage and long‐term antimicrobial treatment. Conclusion: Right dorsal colitis can be treated successfully with resection and bypass of the RDC. In cases where the thoracic cavity is penetrated during the abdominal approach, the diaphragm should be sutured to the body wall at the beginning of surgery to avoid development of an infection within the thoracic cavity. Clinical Relevance: RDC resection and bypass may be an alternative approach for management of horses with right dorsal colitis.