Impact of periarticular osteophytes of the distal tarsus diagnosed in nonlame yearling Standardbred horses on racing performance.

OBJECTIVE: The aim of this study was to identify the radiographic prevalence of periarticular osteophytes of the distal tarsus in nonlame yearling Standardbred horses, and to evaluate its potential impact on race performance. STUDY DESIGN: Cross-sectional cohort study. ANIMALS: Client-owned yearling Standardbred horses (n = 416). METHODS: Bilateral tarsal radiographs were available from all horses for review. Osteophytes were measured on radiographs using clinical visualization software and categorized by size. Racing records were obtained from the United States Trotting Association. Regression analysis was used to determine associations between presence or size of periarticular osteophytes and performance parameters with sex and gait covariates. RESULTS: Of 416 Standardbred yearlings without clinical lameness, 113 (27.1%) had distal tarsal periarticular osteophytes. Regression analyses revealed few associations between the presence of periarticular osteophytes and performance parameters. Affected horses had fewer starts at 4 years of age (incident rate ratio [IRR] 0.92, p = .01) and fewer lifetime starts (IRR 0.95, p = .003), but the effect size was small. Within the affected group, osteophyte size was only associated with number of starts at 3 (IRR 0.67, p < .0001). Sex and gait affected many performance parameters. CONCLUSION: The prevalence of distal tarsal periarticular osteophytes was similar to that in other breeds. Periarticular osteophytes of the distal tarsus appeared to be a largely incidental finding in nonlame yearling Standardbreds intended for harness racing. CLINICAL SIGNIFICANCE: Distal tarsal periarticular osteophytes in young, nonlame Standardbred horses should affect racing potential only minimally. This is in contrast to reports from other disciplines.

COMPARISONS AMONG RADIOGRAPHY, ULTRASONOGRAPHY AND COMPUTED TOMOGRAPHY FOR EX VIVO CHARACTERIZATION OF STIFLE OSTEOARTHRITIS IN THE HORSE.

A better understanding of imaging characteristics of equine stifle osteoarthritis (OA) may allow earlier detection and improve prognosis. Objectives of this ex vivo, prospective, methods comparison study were to (1) describe the location and severity of naturally acquired OA lesions in the equine stifle using ultrasound (US), radiography (XR), computed tomography (CT), and macroscopic evaluation (ME); (2) compare the diagnostic performance of each imaging modality with ME; and (3) describe subchondral bone mineral density (BMD) in equine stifle joints with OA using CT. Radiographic, CT, and US evaluations were performed on 23 equine cadaver stifles and compared with ME. Significant associations were found between osteophyte global scores for all imaging modalities (CT, P ˂ 0.0001; XR, P = 0.005; US, P = 0.04) vs. ME osteophyte global scores. Osteophytes were detected most frequently in the medial femorotibial (MFT) joint. A specific pattern of osteophytes was observed, with a long ridge of new bone at the insertion of the MFT joint capsule cranially on the medial femoral condyle. A novel caudo-10°proximo-5°lateral-cranio-disto-medial oblique radiographic projection was helpful for detection of intercondylar osteophytes. Multiplanar CT reformatted images were helpful for characterizing all osteophytes. Osteophyte grades at most sites did not differ among modalities. Low sensitivity/specificity for subchondral bone sclerosis and flattening of femoral condyles suggested that these signs may not be reliable radiographic and CT indicators of equine stifle OA. Equine stifle OA was associated with a decrease in BMD and specific sites of focal subchondral bone resorption/cyst formation were found in some specimens.

Chronic desmitis and enthesiophytosis of the radio-ulnar interosseous ligament in a dog.

A 10-year-old golden retriever dog was presented for chronic right forelimb lameness associated with a painful swelling at the lateral aspect of the proximal ulna. Proximal ulnar ostectomy and stabilization resulted in a good clinical outcome. The proposed diagnosis is chronic desmitis and enthesiophytosis of the radio-ulnar interosseous ligament.

Desmite chronique et enthésiophytose du ligament interosseux radio-ulnaire chez un chien. Un Golden retriever de 10 ans a été présenté pour boiterie chronique du membre thoracique droite associée à un gonflement douloureux à l'aspect latéral de l'ulna proximal. Une ostéotomie ulnaire proximale avec stabilisation ont permit un bon résultat clinique. Le diagnostic proposé est une desmite chronique et enthésiophytose du ligament interosseux radio-ulnaire.(Traduit par Isabelle Vallières).

Prevalence and characterization of small tympanic bone spicules and drumstick-like hyperostotic tympanic bone spicules in the middle ear cavity of dogs.

Rounded, sessile, hyperattenuating structures detected in computed tomography (CT) studies of canine tympanic bullae have been termed "otoliths." These have been proposed to represent dystrophic mineralizations or heterotopic bone formations in the middle ear that are potentially related to chronic otitis media. Aims of the current study were to describe the prevalence, macroscopic, and histological features of structures consistent with "otoliths" in the canine tympanic cavity. Tympanic bullae from 50 routinely necropsied dogs and 139 retrospectively retrieved CT scans of canine clinical cases were examined. Small tympanic bone spicules with pointed or clubbed tips essentially arising from the free margin of the septum bullae were bilaterally present in the tympanic cavities of all 50 of the necropsied dogs. In 48% of the dogs, "otolith"-like CT-detectable bone spicules carrying drumstick-like hyperostoses that were 1-6 mm in diameter were also present. In the retrospective survey of bulla CT scans of 139 cases, the prevalence of hyperostotic tympanic bone spicules (HTBS) was 20%. Findings from the current study indicated that the presence of small tympanic bone spicules in adult dogs is most likely due to physiological bone growth in the septum bullae and that HTBS represent osseous proliferations of small tympanic bone spicules. However, the factors inducing formation of hyperostotic spicules from small tympanic bone spicules remain unknown. The high prevalence of HTBS displaying a similar appearance in bulla CT scans in dogs suggests that these spicules should be included in a differential diagnosis list for "otoliths."

Degree of osteophyte formation seen on radiographs provides useful prognostic information for dogs with cruciate ligament disease.

BACKGROUND: Concurrent osteoarthritis is generally present in the stifle joints of dogs with cranial cruciate ligament disease (CCLD), but it is not known if the degree of osteoarthritis-related changes affects the prognosis. Development of osteophytes is a key radiographic feature of osteoarthritis. The aim of this study was to evaluate the association between the degree of osteophyte formation seen on radiographs and CCLD-related euthanasia in dogs with CCLD. METHODS: A retrospective cohort study including 226 dogs treated for CCLD at two university animal hospitals was performed. Clinical and follow-up information was retrieved, and stifle radiographs taken during the 31 days before treatment for the CCLD were graded for osteophyte formation by three veterinary radiologists. A multivariable Cox proportional hazards model was applied to assess the association between the degree of osteophyte formation and CCLD-related euthanasia. RESULTS: An association between the degree of osteophyte formation and CCLD-related euthanasia was found, with increased osteophyte formation associated with an increased hazard of CCLD-related euthanasia (hazard ratio 1.06, 95% confidence interval 1.01-1.11, p = 0.01). LIMITATIONS: No clinical assessment of the outcome was performed. CONCLUSION: The findings suggest that evaluation of stifle radiographs for osteophyte formation could provide useful prognostic information for dogs with CCLD.

Clinical significance of osseous spurs on the dorsoproximal aspect of the third metatarsal bone.

REASONS FOR PERFORMING STUDY: Osseous spurs on the dorsoproximal aspect of the third metatarsal bone (MtIII) are common, but their clinical significance is unknown. OBJECTIVES: To verify the sites of insertion of the dorsal metatarsal ligament and the tendons of tibialis cranialis and fibularis tertius in order to determine if periarticular osteophytes and entheseophytes could be differentiated radiologically; and to determine the frequency of occurrence of osseous spurs on the dorsoproximal aspect of MtIII. HYPOTHESES: The frequency of osseous spurs on the dorsoproximal aspect of MtIII would be higher in lame than in clinically normal horses and higher in horses with distal hock joint pain or proximal suspensory desmitis than in horses with other causes of hindlimb lameness. METHODS: A retrospective study of data from the clinical work up and tarsal radiographs of 455 horses was performed. Horses were divided into: Group 1, clinically normal horses; Groups 2-5, according to the diagnosis of hindlimb lameness. Radiographs were examined for the presence of an osseous spur on the dorsoproximal aspect of MtIII; pathology of the distal tarsal joints was graded. The associations between the presence of a spur and lameness, diagnosis group and the grade of distal tarsal joint abnormalities were analysed statistically using Chi-squared tests. RESULTS: An osseous spur was present in 25% of horses; 13% of horses with bilateral radiographs had bilateral spurs. There was no significant difference in frequency of the presence of a spur between lame and nonlame horses, or between horses with other causes of hindlimb lameness and horses with proximal suspensory desmitis and/or distal tarsal joint pain. The presence of an osseous spur was significantly associated with the grade of radiological abnormality in the distal tarsal joints (tarsometatarsal joint P = 0.018: centrodistal joint P = 0.027). In many horses it was not possible to differentiate accurately between osteophytes and entheseophytes. CONCLUSIONS AND POTENTIAL RELEVANCE: The presence of an osseous spur on the dorsoproximal aspect of MtIII in the absence of other radiological abnormalities may be an incidental finding. Osseous spurs occur more frequently in hocks with radiological abnormalities in the distal tarsal joints and may be an indicator of distal tarsal joint osteoarthritis. The clinical significance must be established by intra-articular analgesia.

Imaging and histological features of central subchondral osteophytes in racehorses with metacarpophalangeal joint osteoarthritis.

REASONS FOR PERFORMING STUDY: Marginal osteophytes represent a well known component of osteoarthritis in man and animals. Conversely, central subchondral osteophytes (COs), which are commonly present in human knees with osteoarthritis, have not been reported in horses. OBJECTIVES: To describe and compare computed radiography (CR), single-slice computed tomography (CT), 1.5 Tesla magnetic resonance imaging (MRI), and histological features of COs in equine metacarpophalangeal joints with macroscopic evidence of naturally-occurring osteoarthritis. METHODS: MRI sequences (sagittal spoiled gradient recalled echo [SPGR] with fat saturation, sagittal T2-weighted fast spin echo with fat saturation [T2-FS], dorsal and transverse T1-weighted gradient-recalled echo [GRE], and sagittal T2*-weighted gradient echo with fast imaging employing steady state acquisition [FIESTA]), as well as transverse and reformatted sagittal CTI and 4 computed radiographic (CR) views of 20 paired metacarpophalangeal joints were acquired ex vivo. Following macroscopic evaluation, samples were harvested in predetermined sites of the metacarpal condyle for subsequent histology. The prevalence and detection level of COs was determined for each imaging modality. RESULTS: Abnormalities consistent with COs were clearly depicted on MRI, using the SPGR sequence, in 7/20 (35%) joints. They were identified as a focal hypointense protuberance from the subchondral plate into the cartilage, at the palmarodistal aspect (n=7) and/or at the very dorsal aspect (n=2) of the metacarpal condyle. COs were visible but less obvious in 5 of the 7 joints using FIESTA and reformatted sagittal CT, and were not identifiable on T2-FS, T1-GRE or CR. Microscopically, they consisted of dense bone protruding into the calcified cartilage and disrupting the tidemarks, and they were consistently associated with overlying cartilage defects. CONCLUSIONS: Subchondral osteophytes are a feature of osteoarthritis of equine metacarpophalangeal joints and they may be diagnosed using 1.5 Tesla MRI and CT. POTENTIAL RELEVANCE: Central subchondral osteophytes on MRI represent indirect evidence of cartilage damage in horses.

Radiographic and arthroscopic findings in the elbow joints of 263 dogs with medial coronoid disease.

OBJECTIVE: To report clinical, radiographic, and arthroscopic findings in dogs with thoracic limb lameness attributed solely to disease of the medial aspect of the coronoid process (MCP). STUDY DESIGN: Case series. ANIMALS: Dogs (n=263) with MCP disease (MCD; 437 elbows). METHODS: Clinical records (January 2000-July 2006) and radiographs were reviewed and pertinent data recorded. Radiographic interpretation included measures of periarticular osteophytosis, gross assessment of MCP integrity, and measurement of ulnar subtrochlear sclerosis (STS). Statistical analysis was performed to evaluate associations between data; confidence interval was set at 95%. RESULTS: Labrador Retrievers were 50.2% of all dogs with MCD. Mean age at diagnosis was 32 months and duration of lameness was 14.5 weeks. Thirteen elbows (3%) were considered radiographically normal. Osteophytosis was identified on the anconeal process (70.2%), radial head (37.3%), and lateral epicondyle (56.5%), and STS was identified in 86.7% of elbows. Median osteophytosis score was 1; mean absolute osteophytosis score was 1.7. Arthroscopic findings included: fissuring (18.3%) and fragmentation (64.1%) of the MCP and kissing lesions (49.0%) of elbows. Median-modified Outerbridge score of the MCP was 2 and the humeral condyle, 0. Weak or moderate correlations were found between osteophytosis and modified Outerbridge scores and weak correlation between modified Outerbridge scores of the MCP and medial humeral condyle. CONCLUSIONS: Wide ranges in clinical, radiographic, and arthroscopic findings are recognized in dogs with MCD but correlations between such factors are generally weak. Radiographic and arthroscopic findings do not correlate with owner-reported duration of lameness. CLINICAL RELEVANCE: Radiographic measures of osteophytosis are poor predictors of severity of arthroscopic pathology for MCD.

Measurement of ulnar subtrochlear sclerosis using a percentage scale in labrador retrievers with minimal radiographic signs of periarticular osteophytosis.

OBJECTIVE: To report the development of a measurement method for quantifying ulnar subtrochlear sclerosis (STS) in Labrador Retrievers. STUDY DESIGN: Prospective blinded study. SAMPLE POPULATION: Radiographs of Labrador Retrievers elbows (n=30) with minimal radiographic signs of periarticular osteophytosis. METHOD: Measurement of STS as a % of the distance between 2 standardized radiographic landmarks (%STS) was developed. Mediolateral radiographic projections of flexed elbows were collected from 2 cohorts termed diseased (n=15; confirmed disease of the medial coronoid process) and control (n=15; free from clinically evident disease). Five observers blindly assessed each radiograph for radiographic technique, elbow positioning, periarticular osteophytosis, and STS, which, if present, was measured and assigned a %STS score. Intraobserver and interobserver variations in measuring STS and the ability to differentiate study cohorts were assessed using receiver operator curve (ROC) characteristics. A P-value of <.05 was considered significant. RESULTS: Median %STS for diseased elbows was 47% (range, 0-74%) and 0% (range, 0-62%) for control elbows. Correlations were not significantly different between each observer's assessments of %STS, with a median Spearman's P-value of .75 (range, .67-.86). All observers differentiated the 2 cohorts with "fair-good" accuracy, with a median ROC value of 0.81 (range, 0.75-0.88). CONCLUSION: Measurement of %STS in Labrador Retrievers was repeatable for each observer and repeatable between observers. CLINICAL RELEVANCE: A method for measuring STS allows comparison of Labrador Retrievers of different sizes, is easy to perform, and could be used to investigate the clinical significance of STS in this breed.

Characterization of bony changes localized to the cervical articular processes in a mixed population of horses.

The objectives of this observational, cross-sectional study were to characterize and establish the prevalence of osseous proliferation of articular surfaces, joint margins and adjacent soft tissue attachments (i.e., joint capsule and deep spinal muscles) in a mixed population of horses of variable ages, sizes, and breeds to better capture the full spectrum of disease affecting the cervical articular processes. Cranial and caudal articular processes of the cervical and first three thoracic vertebrae (C2-T3) from 55 horses without a primary complaint of neck pain were evaluated for the presence and severity of abnormal bony changes. Data were analyzed to compare alterations in joint margin quadrants, paired articular surfaces within a synovial articulation, left-right laterality, and vertebral level distributions and to determine associations with age, wither height and sex. Seventy-two percent of articular processes had bony changes that were considered abnormal. Osteophyte formation was the most common bony change noted. Overall grades of severity included: normal (28%), mild (45%), moderate (22%), and severe (5%). The highest prevalence of mild changes was localized to the C3-C6 vertebral levels; moderate changes to C6-T2; and severe changes to C2-C3 and C6-T2. Most paired articular surfaces and left-right grades of severity were not significantly different. The grade of osseous pathology was positively associated with both age and wither height. A high prevalence and wide variety of abnormal bony changes of varying severity were found in articular processes across all vertebral levels. The clinical significance of the described lesions is unknown, but the findings are expected to enhance the reporting of articular process and periarticular changes noted on advanced diagnostic imaging of the equine cervical and cranial thoracic vertebral regions.

Puppy line, metaphyseal sclerosis, and caudolateral curvilinear and circumferential femoral head osteophytes in early detection of canine hip dysplasia.

Ventrodorsal extended hip radiographs were analyzed from Foxhounds, Irish setters, Greyhounds, and Labrador retrievers radiographed four to seven times between 8 and 110 weeks of age. Occurrence in these 91 dogs of a puppy line, an ill-defined zone of proximal femoral metaphyseal sclerosis, a femoral neck linear sclerosis, or circumferential linear femoral head osteophytosis at 15-17 weeks of age were compared with hip joint laxity, as measured by distraction index, and to later findings of caudal curvilinear femoral neck osteophytes, circumferential femoral head osteophytes, hip incongruity consistent with hip dysplasia and degenerative joint disease by 52 weeks of age. A puppy line and/or femoral metaphyseal sclerosis was common at 15-17 weeks of age for dogs at mimimal risk (Greyhounds) and high risk (Foxhounds) of developing early degenerative joint disease associated with canine hip dysplasia. Though 44% of Greyhound hips had puppy lines and 28% had femoral metaphyseal sclerosis at 15-17 weeks of age, no Greyhound had a caudolateral curvilinear osteophyte or circumferential femoral head osteophyte at 24-27 or 52 weeks of age. No significant relationship was found between occurrence of a puppy line, a circumferential femoral head osteophyte or femoral metaphyseal sclerosis at 15-17 weeks and canine hip dysplasia or degenerative joint disease incidence at 42-52 weeks. Presence of a caudolateral curvilinear osteophyte in at least one hip at 24-27 weeks was significantly related to the diagnosis of canine hip dysplasia by 42-52 weeks. When both a caudolateral curvilinear osteophyte and a circumferential femoral head osteophyte were present in a hip at 24-27 weeks, degenerative joint disease was evident in all such hips by 42-52 weeks of age.