Equine studies
Outcome measures regarding disease-modifying changes were less common but reported in four equine studies (Todhunter et al., 1998; Kay et al., 2008; Kearney et al., 2021) and included synovial fluid (SF) measurements (total protein [TP], cell counts, OA biomarkers, glycosaminoglycans, and prostaglandin E2[PGE2]), histopathology of cartilage and synovial membrane (SM), and measurements of protein synthesis and total proteoglycans in cartilage.
In equine studies, TA showed improvements by decreasing SF TP, reducing metalloproteinase (MMP) activity and chemokines (CCL2) (Kay et al., 2008; Kearney et al., 2021); however, drawbacks such as increased PGE2 SF concentrations were also found, was a transient decrease in glycosaminoglycans (GAG) (Kearney et al., 2021). Results regarding white blood cell (WBC) counts in SF were not consistent between studies (Kay et al., 2008; Kearney et al., 2021).
MPA was evaluated in two equine studies, in which one found no significant changes regarding SF, TP, cell counts, histopathology of cartilage and SM, and proteoglycan (PG) and protein synthesis in cartilage. However, increases in small PG were found by one author (Todhunter et al., 1998), and suppression of matrix protein markers of chondrocyte differentiation was found by another, which could be associated with cartilage degeneration (Fubini et al., 2001).