The Effect of Trans-Stifle External Skeletal Fixation and Hyaluronic Acid Therapy on Articular Cartilage in the Dog

Transarticular external skeletal (TES) fixators were applied unilaterally to the stifle joints of 10 young adult dogs. After 4 weeks, the fixators were removed from all dogs. Two dogs were not allowed a remobilization period, whereas 8 dogs were provided with 4 additional weeks of weight-bearing activity in a kennel run. Four dogs were given high-molecular weight hyaluronic acid by intra-articular injection weekly during the remobilization period. Clinical gait evaluations and range of motion were determined during the remobilization period. Articular cartilage samples from both stifle joints of all dogs were evaluated histologically and histochemically. No significant differences in gait scores or range of motion were noted between treated and untreated dogs. Articular cartilage proteoglycan content was reduced after 4 weeks of trans-stifle external skeletal fixation as determined by loss of alcian blue (AB) histochemical staining. Improved homogeneity of histochemical staining was observed after remobilization. However, remobilization was associated with histological damage to the surface and tangential layers of articular cartilage. Remobilization combined with hyaluronic acid (HA) therapy improved histochemical staining and reduced structural damage to articular cartilage when compared with remobilization alone.     

Treatment of Forelimb Growth Plate Deformity in 11 Dogs by Radial Dome Osteotomy and External Coaptation

Radial dome osteotomy and external coaptation were used to correct forelimb growth deformities with carpal valgus angles of 15 to 43 degrees in 11 dogs (12 forelimbs). Osteotomy sites were clinically healed by week 4. Appearance and function in 10 limbs was good to excellent. The angular deformity recurred in one dog by week 4 due to partial closure of the distal radial growth plate. Carpal valgus recurred in one dog by week 2 because the ulnar osteotomy healed before radial growth ceased.     

Ischemic Postconditioning Does Not AttenuateIschemia–Reperfusion Injury of Rabbit Small Intestine

Objective— To determine whether ischemic postconditioning can attenuate intestinal ischemia–reperfusion (I–R) injury and has a beneficial effect on tissue blood flow during reperfusion. Study Design— In vivo experimental study. Animals— New Zealand White rabbits (n=6). Methods— Rabbits were anesthetized with pentobarbital, to avoid the preconditioning effects of volatile anesthetics, and ventilated with room air. Rectal temperature, hemodynamics, and normocapnia were maintained. After celiotomy, 3 jejunal segments were isolated in each rabbit for the following groups: (1) control, (2) I–R, and (3) I–R with postconditioning. I–R was induced by a 45‐minute occlusion of the segment jejunal artery followed by 2‐hour reperfusion. The postconditioning segment had 4 cycles of 30‐second reperfusion and 30‐second reocclusion during the initial 4 minutes of reperfusion. Stable isotope‐labeled microspheres were used to measure intestinal blood flow at baseline, end occlusion, and end reperfusion. At the end of reperfusion, intestine segments were harvested and the rabbits euthanatized. A semiquantitative histopathologic evaluation (0–5) was conducted by a single, blinded observer. Wet‐to‐dry weight ratios were calculated to assess intestinal edema. Results— There was no significant difference in grade of necrosis, tissue wet‐to‐dry weight ratios, or blood flow at any time point between ischemic and postconditioning groups. Conclusions— Ischemic postconditioning was ineffective in this model of intestinal I–R. Clinical Relevance— Further experimental studies will need to be performed before clinical application of postconditioning for intestinal ischemia.     

Incorporation of Fresh and Cryopreserved Bone in Osteochondral Autografts in the Horse

The structural integrity of subchondral bone in fresh and frozen osteochondral autografts was investigated at month 3 in 10 horses. Two osteochondral autografts were harvested from the lateral aspect of the lateral trochlear ridge of the left talus in each of 10 anesthetized horses. Grafts were frozen in 7.5% DMSO. After 14 days, the thawed grafts were press-fitted into drill holes in the trochlear ridges of the right stifles. A fresh graft from the right hock was implanted in each left stifle. To control for the effects of surgery, a fresh graft was transferred from the right stifle to the left stifle. The end result was two grafts in each femoropatellar joint. Fresh and frozen bone grafts maintained a structurally intact support for the cartilage surface. Graft stability and surface congruency were determining factors in the outcome of the grafts. Incorporation of both types of graft was complete at month 3, but remodeling of the fresh grafts was more active.     

Validation of a Rapid Parathyroid Hormone Assay and Intraoperative Measurement of Parathyroid Hormone in Dogs with Benign Naturally Occurring Primary Hyperparathyroidism

Objectives— To (1) validate a rapid chemiluminescent parathyroid hormone (PTH) assay, (2) determine it's usefulness locating a parathyroid nodule(s), and (3) determine if >50% decrease in PTH corresponds with excision of autonomously functioning parathyroid tissue. Study Design— Prospective cohort study. Animals— Dogs (n=12) with naturally occurring primary hyperparathyroidism and 25 healthy dogs. Methods— The assay was validated with linearity, precision, and intermethod comparison. Preoperative and postoperative systemic plasma PTH concentrations, measured from saphenous venous blood, were compared. Intraoperative local PTH concentrations were measured in right and left jugular venous blood before and after surgical excision of the grossly abnormal parathyroid gland(s). Results— Within run and day‐to‐day precisions were acceptable (coefficient of variation <15%). Dilutional parallelism was used to demonstrate high correlation between measured and calculated PTH concentrations (R²=0.99). The assay methods had good correlation but numerical results of the rapid assay were usually lower than the immunoradiometric assay. Seven of 12 dogs had uniglandular disease and five had multiglandular disease. Systemic and local PTH concentrations decreased >50% in all the dogs after excision of the parathyroid gland(s). Mean preoperative systemic plasma PTH concentrations were significantly higher than mean postoperative systemic concentrations. Local PTH concentrations could not be used reliably to differentiate the side of the autonomously functioning gland(s). Hypercalcemia resolved postoperatively in all the dogs. Conclusion— This assay measures PTH in dogs. Rapid PTH measurement provided documentation of decreased PTH concentration after removal of autonomously functioning parathyroid tissue. Clinical Relevance— Use of this assay allows documentation of a significant decrease in PTH concentration after excision of autonomously functioning parathyroid tissue.     

Total and Partial Orbitectomy for the Treatment of Periorbital Tumors in 24 Dogs and 6 Cats: A Retrospective Study

Total or partial orbitectomy were used to treat 24 dogs and six cats with invasive periorbital tumors. The surgical procedure and clinical results were evaluated in this retrospective study. The most common types of tumors treated in this series of patients were multilobular osteochondrosarcoma and squamous cell carcinoma. Two patients died of cardiopulmonary arrest within 24 hours after surgery. One patient developed neurological signs after total orbitectomy that resolved with conservative therapy. Minor complications, which included infection, strabismus, and conjunctivitis, occurred in seven patients. Regrowth of tumor in the periorbital region occurred in 11 patients (36.7%). Tumor resection by orbitectomy provided local disease-free interval of more than 1 year in more than 50% of patients. Survival rate for the first year was 70.4% in this series of patients as determined by life table analysis. Orbitectomy requires detailed knowledge of regional anatomy and experience with performing a combination of surgical procedures. Preoperative diagnostic tests should include imaging techniques to define the extent of the disease. When performed properly, orbitectomy is a valuable procedure that can be used to effectively treat invasive tumors of the orbit.     

Gradual Occlusion of Extrahepatic Portosystemic Shunts in Dogs and Cats Using the Ameroid Constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.