The aetiology of primary uterine inertia (PUI), which is the most common cause of canine dystocia, is still not elucidated. Prostaglandins (PGs) play a crucial role in parturition. We hypothesized that the expression of prostaglandin endoperoxidase synthase 2 (PTGS2), PGF2α synthase (PGFS), and corresponding receptor (PTGFR) is altered in PUI. We investigated PTGS2 , PGFS , and PTGFR mRNA expression, and PTGS2 and PGFS protein...