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Objective—To study osteoarthritis in the equine medial femorotibial (MFT) joint after a single traumatic injury.

Animals—10 mature horses.

Procedure—In vitro explant cultures were used to determine injury threshold for stifle joint cartilage. Contusive impacts were applied to the medial femoral condyle (MFC), and horses were followed for 84 (n = 5) and 180 days (5). Synovial fluid samples were collected every 14 days for determination of sulphated glycosaminoglycan (sGAG) concentrations. Radiographic and lameness evaluations were performed. Gross and histologic descriptions, and immunohistochemistry, cartilage sGAG content determination, and cartilage aggregate modulus determination were performed at the MFC impact site (MFCi), MFC nonimpact site (MFCn), and medial tibial plateau (MTP).

Results—Synovial fluid sGAG concentration decreased significantly on days 14, 28, 42, and 56 in all horses. Macroscopic and microscopic articular lesions developed within all MFT joints. No radiographic abnormalities were observed. Mild lameness was evident in several horses. No significant differences were found between short-term and longterm cohorts of horses with respect to histologic scores and TUNEL results. On immunohistochemistry, MFCi was positive for COL2–¾Cshort. International Cartilage Repair Society scores differed significantly between short-term and long-term cohorts of horses. In all horses, sGAG concentrations were significantly decreased at the MFCi, compared with the MFCn.

Conclusions and Clinical Relevance—Use of contusive impacts on the MFC of horses results in cartilage lesions that are similar to those described clinically, supporting trauma as a contributing factor in the natural pathogenesis of osteoarthritis.

Full access
in American Journal of Veterinary Research


Objective—To determine whether a single contusive impact injury to the palmar aspect of the metacarpus would progress to post-traumatic osteoarthritis or palmar osteochondral disease in horses.

Animals—12 horses.

Procedures—In each horse, an impact injury was created on the palmar aspect of the medial metacarpal condyle of 1 randomly chosen limb with an impactor device under arthroscopic and fluoroscopic guidance. The opposite limb was sham operated as a control. A low to moderate amount of forced exercise was instituted, and horses were evaluated clinically via lameness examinations weekly for 5 months, then biweekly until endpoint, with synovial fluid analysis performed at 0, 1, 2, 3, 4, 6, 8, and 10 months and radiography at baseline and endpoint. Macroscopic examination, micro-CT, and sample collection for cartilage viability and sulfated glycosaminoglycan content, histologic evaluation, immunohistochemical analysis, and fluorochrome analysis were performed following euthanasia at 1 (3 horses), 4 (4), and 8 to 10 (5) months after surgery.

Results—There was variability in impact lesion location, depth, and area on macroscopic inspection, but on histologic evaluation, cartilage defects were less variable. Mean sulfated glycosaminoglycan concentration from cartilage at the impact site was significantly lower than that at a similar site in control limbs. Higher concentrations of cartilage oligomeric matrix protein were observed in synovial fluid from impact-injured joints.

Conclusions and Clinical Relevance—The impact injury method caused mild focal osteoarthritic lesions in the metacarpophalangeal joint, but did not progress to palmar osteochondral disease at this site. Repeated injury is probably required for the development of palmar osteochondral disease.

Full access
in American Journal of Veterinary Research


Objective—To determine whether Neospora caninum serostatus was associated with milk production among Holstein cattle in Ontario.

Design—Case-control study and cross-sectional observational study.

Animals—3,702 Holstein cows in 83 herds (casecontrol study) and 3,162 Holstein cows in 57 herds.

Procedure—Herds in the case-control study were grouped on the basis of N caninum abortion status. Herds in the observational study were considered representative of Ontario dairy herds. The N caninum serostatus of individual cows was determined with a kinetic ELISA. Milk production was modeled to compare seropositive with seronegative animals while controlling for parity, days since parturition, and herd clustering.

Results—In the case-control study, 305-day milk production of seropositive cows was significantly less than milk production of seronegative cows in herds with abortions attributable to N caninum infection and in herds with abortions attributable to pathogens other than N caninum, but not in herds without abortion problems. In the observational study, 305-day milk production for seropositive cows was not significantly different from milk production of seronegative cows.

Conclusions and Clinical Relevance—Results suggest that the association between N caninum serostatus and milk production in Ontario Holstein dairy cattle may depend on abortion status of the herd. In herds with abortion problems, regardless of cause, N caninum-seropositive cattle produced less milk, whereas in herds without abortion problems, N caninum-seropositive cattle produced the same amount of milk as seronegative cattle. (J Am Vet Med Assoc 2002;221:1160–1164)

Full access
in Journal of the American Veterinary Medical Association