Is there a relationship between clinical presentation, diagnostic and radiographic findings and outcome in horses with osteoarthritis of the small tarsal joints?
BACKGROUND
Despite the possibility that sound horses may have radiographic signs consistent with osteoarthritis of the small tarsal joints (OA-STJ), a diagnosis of 'bone spavin' as a cause of lameness is often made based only on radiographic examination.


OBJECTIVE
To determine whether severity of radiographic change and response to treatment are correlated with the duration and degree of lameness and the response to intraarticular anaesthesia in horses with OA-STJ.


METHODS
A retrospective study of all horses that showed a positive response to intra-articular anaesthesia of the STJ was performed. Details of history, clinical presentation and diagnostic findings were recorded. Radiographs of affected tarsi were evaluated and scored independently by 2 observers. Follow-up was via a telephone questionnaire with the owner. Statistical analysis was used to assess the association between the duration and degree of lameness, the response to intra-articular anaesthesia and radiographic findings. Response to treatment was compared with the findings from the diagnostic work-up.


RESULTS
Ninety-one horses were included (61 unilateral and 30 bilateral lameness). Fifty-nine percent of horses had been lame for over 2 months. There was no association between the duration and degree of lameness, or between duration or degree of lameness, intra-articular anaesthesia and radiographic findings. Response to treatment showed a significant positive association with less severe radiographic changes within the tarsometatarsal (TMT) joint. Follow-up was available for 48% of cases, with 52% horses returning to the same level of exercise.


CONCLUSIONS
There is no association between the duration and degree of lameness, the response to intra-articular anaesthesia and radiographic findings in horses with OA-STJ. However, horses that improved following treatment tended to have less marked TMT joint pathology.


CONCLUSIONS
Response to intra-articular anaesthesia should remain the gold standard for diagnosis of OA-STJ. Predicting which cases are likely to improve following treatment remains difficult.
Division of Veterinary Clinical Studies, University of Liverpool, Leahurst, Neston, Cheshire CH64 7TE, UK.
K L
KL
Byam-Cook
E R
ER
Singer
D000758:Anesthesia / Q000379:methods / Q000662:veterinary*; D000818:Animals; D005260:Female; D005500:Follow-Up Studies; D006734:Horse Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D006736:Horses; D007270:Injections, Intra-Articular / Q000662:veterinary; D007794:Lameness, Animal / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D010003:Osteoarthritis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D011379:Prognosis; D011859:Radiography; D012720:Severity of Illness Index; D013640:Tarsal Joints / Q000000981:diagnostic imaging / Q000473:pathology*; D013643:Tarsus, Animal / Q000000981:diagnostic imaging / Q000473:pathology; D016896:Treatment Outcome