This study aimed the efficacy of meloxicam (MX) in treating acute clinical mastitis (ACM)
without systemic symptoms in Holstein cows by studying improvement in udder pain, changes
in prostaglandin E
2
(PGE
2
) and bradykinin (BK) levels in the milk,
and milk yield (MY) after healing. Forty-two cows with ACM were randomly assigned to the
MX treatment group (T group; n=21) and the control group (C group; n=21). At onset of
illness (day 0), the T group received a 0.5 mg/kg subcutaneous (SC) injection of MX
whereas the C group received 15 mL SC of saline solution as a placebo. Udder tenderness
(UT) was measured, and milk samples were collected on days 0–3. There was little change in
the MY of the T group before and after healing, whereas MY in the C group was
significantly lower than after healing. UT on day 3 in the T group was significantly lower
than that in the C group. PGE
2
levels significantly decreased from day 0 to day
3 in both groups. A significant negative correlation between PGE
2
and linear
score was observed on day 1 in the T group, but not in the C group. In ACM without
systemic symptoms, the administration MX may be useful for restoring MY and reducing udder
pain after healing.