Table 3 Baseline clinical characteristics of racehorses at the time of inclusion and during the study period

Standardbred racehorses with at least 6 months of training at the time of inclusion, no. (%)

35 (94 %)

37 (100 %)

Gender, no. (%) male/no. (%) female/no. (%) gelding/no. (%)

16 (43 %)/12 (32 %)/9 (24 %)

11 (29 %)/16 (43 %)/10 (27 %)

Age at the moment of the enrolment (months)

32 (27–35)

34 (29–35)

Disease duration, referring to the lameness identification (days)

5 (2–19)

–

Administration of anti-inflammatory therapy before diagnosis, no. (%)

5 (14 %)

–

Lameness score at clinical examination (0–5 scale)

2 (2–3)

0

Flexion test response in the affected leg at clinical examination (0–3 scale)

2 (1–3)

0

Horses sound after intra-articular analgesia with mepivacaine, no. (%)

22 (61 %)

–

Horses sound after low 4-points-metacarpal (6-points-metatarsal) nerve block, no. (%)

15 (39 %)

–

Radiographic score of the affected fetlock joint at T0 (0–33 scale)

5 (2–11)

0

Osteochondral fragmentation at the dorsal border of the proximal phalanx, no. (%)

9 (24 %)

–

MRI findings of subchondral bone trauma in the metacarpal/metatarsal epiphysis or subchondral bone of the proximal phalanx, no. (%)

3 (8 %)

–

Horses with haemarthrosis in the synovial fluid at clinical presentation, no. (%)

4 (11 %)

–

US findings of fetlock joint synovitis (thickening of the dorsal plica, increased synovial fluid)

29 (76 %)

–

Arthroscopic surgery to remove osteochondral fragmentation, no. (%)

8 (21 %)

–

Animals treated intra-articularly^a, no. (%)

28 (76 %)

–

Animal treated intravenously or intramuscularly^b, no. (%)

8 (21 %)

–

Days of box-rest after traumatic fetlock OA, before to gain training

42 (28–198)

Animals retired because additional muscoloskeletal injuries or other medical problems during the study period, no. (%)

9 (24 %)

17 (46 %)

Animals exluded because they were positive at doping controls/received corticosteroids intra-articularly, no. (%)

3 (8 %)

4 (11 %)

Animals that completed the time-course of the study, no. (%)

25 (68 %)

16 (43 %)