Objective-To determine the radiographic methods that best predict the development of osteoarthritis in the hip joints of a cohort of dogs with hip dysplasia and unaffected dogs. Animals-205 Labrador Retrievers, Greyhounds, and Labrador Retriever-Greyhound crossbred dogs. Procedure-Pelvic radiography was performed when the dogs were 8 months old. Ventrodorsal extendedhip, distraction, and dorsolateral subluxation (DLS) radiographs were obtained. An Orthopedic Foundation for Animals-like hip score, distraction index, dorsolateral subluxation score, and Norberg angle were derived from examination of radiographs. Osteoarthritis was diagnosed at the time of necropsy in dogs greater than 8 months of age on the basis of detection of articular cartilage lesions. Multiple logistic regression was used to determine the radiographic technique or techniques that best predicted development of osteoarthritis. Results-A combination of 2 radiographic methods was better than any single method in predicting a cartilage lesion or a normal joint, but adding a third radiographic method did not improve that prediction. A combination of the DLS score and Norberg angle best predicted osteoarthritis of the hip joint or an unaffected hip joint. All models that excluded the DLS score were inferior to those that included it. Conclusions and Clinical Relevance-A combination of the DLS score and Norberg angle was the best predictor of radiographic measures in 8-month-old dogs to determine whether a dog would have normal or osteoarthritic hip joints.

Objective-To evaluate a modified digital imaging technique for quantitative assessment of the grade of osteoarthritis across the proximal articular surface of the first phalanx in horses. Sample Population-6 metacarpophalangeal (fetlock) joint specimens from 6 horses with various stages of osteoarthritis. Procedure-First phalanx specimens, together with 4 gray scale reference calibration targets, were positioned in a bath with the proximal articular cartilage surface submerged in saline (0.9% NaCl) solution. Digital images were obtained from the articular surface before and after staining with Indian ink. Computer-controlled gray level analysis of the nonstained and Indian ink-stained cartilage surfaces and gray scale reference calibration targets was performed by use of the mean pixel value (based on 255-gray scale). An increase in the mean pixel value after staining was used to calculate the cartilage degeneration index (CDI). Results-The CDI of the proximal articular cartilage surface of the first phalanx specimens ranged from 9.2 +/- 5.7 (early stage osteoarthritis) to 41.5 +/- 3.6% (late stage osteoarthritis). The effect of repeating the measurement 6 times in nonstained (including repositioning) and stained specimens (including repositioning and restaining) was not significant. Up to 10 measurements of nonstained specimens could be made without refreshing the bath solution. In stained specimens, mean gray level increased significantly after the sixth measurement. Conclusion and Clinical Relevance-The modified digital imaging technique allowed quantitative assessment of cartilage degeneration across the articular cartilage surface. The CDI is the first quantitative measure for osteoarthritis-induced cartilage degeneration over an entire joint surface in horses.