Objective—To assess effects of zoledronic acid on biomarkers, radiographic scores, and gross articular cartilage changes in dogs with induced osteoarthritis. Animals—21 purpose-bred hound-type dogs. Procedures—The left stifle joint of each dog was examined arthroscopically to determine initial articular cartilage status, which was followed by cranial cruciate ligament (CrCL) transection to induce osteoarthritis. Dogs were assigned to 3 groups (control group, low dose [10 μg of zoledronic acid/kg], or high dose [25 μg of zoledronic acid/kg). Treatments were administered SC every 3 months for 1 year beginning the day after CrCL transection. Serum and synovial fluid samples and radiographs were obtained 0, 1, 3, 6, 9, and 12 months after transection. At 12 months, each joint was scored for cartilage defects. Serum and synovial fluid biomarkers of bone and cartilage turnover (bone-specific alkaline phosphatase, type I and II collagen, carboxy-propeptide of type II collagen, and chondroitin sulfate 846) were analyzed with ELISAs. Results—The high-dose group had fewer total articular defects and lower severity scores in CrCL-transected stifle joints than did the control group. In addition, the high-dose group had significantly less change in collagenase cleavage of type I or II collagen in the synovial fluid at 1 and 3 months after CrCL transection than did the control group and also had greater changes in bone-specific alkaline phosphatase in synovial fluid at 3 months after CrCL transection than did the control group. Conclusions and Clinical Relevance—Zoledronic acid had a chondroprotective effect in dogs with a transected CrCL.

Objective-To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI). Sample-Tendons of 8 young adult horses. Procedures-The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points. Results-At 4 weeks after collagenase injection, the area of maximal injury assessed on cross section was similar between ultrasonography and MRI. In lesions of > 4 weeks' duration, ultrasonography underestimated the area of maximal cross-sectional injury by approximately 18%, compared with results for MRI. Signal intensity of lesions on T1-weighted images was the most hyperintense of all the sequences, lesions on short tau inversion recovery images were slightly less hyperintense, and T2-weighted images were the most hypointense. Signal intensity of tendon lesions was significantly higher than the signal intensity for the unaltered deep digital flexor tendon. Histologically, there was a decrease in proteoglycan content, an increase in collagen content, and minimal change in fiber alignment during the 16 weeks of the study. Conclusions and Clinical Relevance-Ultrasonography may underestimate the extent of tendon damage in tendons with long-term injury. Low-field MRI provided a more sensitive technique for evaluation of tendon injury and should be considered in horses with tendinitis of > 4 weeks' duration.

Objective-To determine significant molecular and cellular factors responsible for differences in secondintention healing in thoracic and metacarpal wounds of horses. Animals-6 adult mixed-breed horses. Procedure-A full-thickness skin wound on the metacarpus and another such wound on the pectoral region were created, photographed, and measured, and tissue was harvested from these sites weekly for 4 weeks. Gene expression of type-I collagen, transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-1, and tissue inhibitor of metalloproteinase (TIMP)-1 were determined by quantitative in situ hybridization. Myofibroblasts were detected by immunohistochemical labeling with α-smooth muscle actin (α-SMA). Collagen accumulation was detected by use of picrosirius red staining. Tissue morphology was examined by use of H&E staining. Results-Unlike thoracic wounds, forelimb wounds enlarged during the first 2 weeks. Myofibroblasts, detected by week 1, remained abundant with superior organization in thoracic wounds. Type-I collagen mRNA accumulated progressively in both wounds. More type-I collagen and TGF-β1 mRNA were seen in forelimb wounds. Volume of MMP-1 mRNA decreased from day 0 in both wounds. By week 3, TIMP-1 mRNA concentration was greater in thoracic wounds. Conclusions and Clinical Relevance-Greater collagen synthesis in metacarpal than thoracic wounds was documented by increased concentrations of myofibroblasts, type-I collagen mRNA, TGF-β1 mRNA, and decreased collagen degradation (ie, MMP-1). Imbalanced collagen synthesis and degradation likely correlate with development of exuberant granulation tissue, delaying healing in wounds of the distal portions of the limbs. Factors that inhibit collagen synthesis or stimulate collagenase may provide treatment options for horses with exuberant granulation tissue.

OBJECTIVE To compare the anticollagenase efficacy of fresh feline, canine, and equine serum and plasma on in vitro corneal degradation. SAMPLE Grossly normal corneas from recently euthanized dogs, cats, and horses and fresh serum and plasma from healthy dogs, cats, and horses. PROCEDURES Serum and plasma were pooled by species and used for in vitro experiments. Corneas were collected and stored at −80°C. Sections of cornea were dried, weighed, and incubated in saline (0.9% NaCl) solution with clostridial collagenase and homologous fresh serum or plasma. Corneal degradation was assessed as the percentage of corneal weight loss and hydroxyproline concentration, compared with results for positive and negative control samples. RESULTS Homologous fresh serum and plasma significantly reduced the percentage of corneal weight loss, compared with results for positive control samples. No significant difference was found in percentage of corneal weight loss between incubation with serum or plasma for feline, canine, and equine corneas. Canine serum and plasma significantly reduced hydroxyproline concentrations, whereas inclusion of feline and equine serum or plasma did not, compared with results for positive control samples. Hydroxyproline concentrations were moderately correlated with percentage of corneal weight loss for feline samples and weakly correlated for equine samples, but they were not correlated for canine samples. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the anticollagenase efficacy of fresh feline, canine, and equine serum was not different from that of plasma. Plasma should be an acceptable substitute for serum in the topical treatment of keratomalacia.

OBJECTIVE To evaluate effects of various concentrations of collagenase and dimethyl sulfoxide (DMSO) on yield of equine adipose-derived multipotent stromal cells (ASCs) before and after cryopreservation. SAMPLE Supragluteal subcutaneous adipose tissue from 7 Thoroughbreds. PROCEDURES Tissues were incubated with digests containing 0.1%, 0.05%, or 0.025% type I collagenase. Part of each resulting stromal vascular fraction was cryopreserved in 80% fetal bovine serum (FBS), 10% DMSO, and 10% Dulbecco modified Eagle medium F-12 and in 95% FBS and 5% DMSO. Half of each fresh and cryopreserved heterogeneous cell population was not immunophenotyped (unsorted) or was immunophenotyped for CD44+, CD105+, and major histocompatability complex class II (MHCII; CD44+-CD105+-MHCII+ cells and CD44+-CD105+-MHCII− cells). Cell proliferation (cell viability assay), plasticity (CFU frequency), and lineage-specific target gene and oncogene expression (reverse transcriptase PCR assays) were determined in passage 1 cells before and after culture in induction media. RESULTS Digestion with 0.1% collagenase yielded the highest number of nucleated cells. Cell surface marker expression and proliferation rate were not affected by collagenase concentration. Cryopreservation reduced cell expansion rate and CD44+-CD105+-MHCII− CFUs; it also reduced osteogenic plasticity of unsorted cells. However, effects appeared to be unrelated to DMSO concentrations. There were also variable effects on primordial gene expression among cell isolates. CONCLUSIONS AND CLINICAL RELEVANCE Results supported the use of 0.1% collagenase in an adipose tissue digest and 5% DMSO in cryopreservation medium for isolation and cryopreservation, respectively, of equine ASCs. These results may be used as guidelines for standardization of isolation and cryopreservation procedures for equine ASCs.

OBJECTIVE To evaluate species differences and effects of storage duration and temperature on the anticollagenase efficacy of canine, feline, and equine serum on in vitro corneal degradation. SAMPLES Corneas and serum from dogs, cats, and horses. PROCEDURES Clinically normal corneas from dogs, cats, and horses were harvested within 2 hours after euthanasia. Serum samples from dogs, cats, and horses were collected and pooled by species. Corneal specimens were incubated with collagenase derived from Clostridium histolyticum, 5mM calcium chloride in saline (0.9% NaCl) solution, and feline, canine, or equine serum that had been stored for 0, 30, 90, or 180 days at −20° or −80°C. Following incubation, the corneal weight loss percentage and hydroxyproline concentration in the incubation fluid were calculated and compared among experimental combinations. RESULTS Feline serum was more effective than canine or equine serum for minimizing corneal weight loss. Incubation with feline or equine, but not canine, serum significantly reduced hydroxyproline production. Serum storage duration did not affect corneal weight loss, but the hydroxyproline concentration was greater for corneal specimens that were incubated with serum that was stored for 90 days, compared with that for corneal specimens incubated with serum that was stored for 0, 30, or 180 days. Serum storage temperature did not affect corneal weight loss or hydroxyproline concentration. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that serum reduced corneal degradation in vitro, and the duration and temperature at which serum was stored did not affect its anticollagenase efficacy.

Different doses of dexamethasone were evaluated for the treatment of cerebral trauma using a rat model of cerebral hematoma induced by intracerebral (IC) stereotaxic injections of collagenase. Control animals received an intracerebral collagenase injection followed by intraperitoneal (IP) saline injection. Sham operated animals received saline only (IC, IP). Forty-eight hours following the surgeries, the brains were removed from the euthanized animals. Cerebral hemispheres were separated and the 4 coronal sections (antero-posterior plane) were weighed. Each slice was dried for 24 h (100°C) and weighed again to establish brain water content. In hematoma-induced saline treated rats, significant differences in brain water content were observed when compared to sham operated animals. Rats treated with 1 mg/kg dexamethasone had a significant brain water content decrease; however, no significant differences were observed with higher doses of dexamethasone. In conclusion, low doses of dexamethasone seem to be beneficial for the treatment of cerebral trauma.

Objective-To determine immunoreactivity of matrix metalloproteinase (MMP)-1, -3, and -13 in cartilaginous tumors of dogs, correlate expression of MMP with histologic grade of tumors and clinical outcome of dogs, and compare MMP immunoreactivity between chondrosarcomas and chondromas. Sample Population-Formalin-fixed, paraffin-embedded tissues obtained from samples of naturally occurring chondrosarcomas (n = 31) and chondromas (8) of dogs that were submitted to our veterinary medical diagnostic laboratory. Procedure-Histologic sections from each sample were stained with H&E and monoclonal antibody to MMP-1, -3, and -13 by use of an avidin-peroxidase immunohistochemical technique. For each section, histologic grade (I, II, or III) and immunohistochemical expression (0, 1, 2, or 3) were evaluated. Clinical outcome was obtained from medical records or interviews with referring veterinarians and scored as a good outcome, moderate outcome, or poor outcome. Correlations among variables and differences between chondrosarcomas and chondromas were analyzed. Results-Samples from chondrosarcomas had significantly higher immunoreactivity of MMP-1 and -13, compared with immunoreactivity in samples from chondromas. In chondrosarcomas, a significant positive correlation (r, 0.386) was found between MMP-1 and -13 immunoreactivities, and a significant negative correlation (r, -0.390) was detected between MMP-3 and -13 immunoreactivities. Conclusion and Clinical Relevance-A significant increase in expression of collagenases (MMP-1 and - 13) in chondrosarcomas, compared with expression in chondromas, suggests that collagenases may play an important role in tumor progression, and possibly metastasis, in chondrosarcomas of dogs.