PARENT SESSION
Pregnancy and Parturition

PROSTAGLANDIN F₂ METABOLITE PROFILES IN COWS WITH RETAINED PLACENTA.

Königsson, Kristian¹, Kindahl, Hans¹, Gustafsson, Hans², ^{1 2}

ABSTRACT- Retained placenta (RP) in cattle is associated with bacterial endometritis. From an endocrine perspective, RP cows have high levels of 15-ketodihydro-PGF₂ (PGFM) immediately post partum (pp) declining to low levels within two weeks. The PGFM profiles in RP cows differ from the profiles in cows without RP (non-RP). The aim of this study was to investigate the PGFM profiles in RP cows treated with the COX-inhibitor, flunixin (F) and/or oxytetracycline (T). As a model, parturition was induced on days 268-270 of pregnancy in 2 x 12 heifers by injection of PGF2. In each experiment the cows were set into 4 groups and treated with either T (10 mg/kg b.w. i.m. once daily), F (2.2 mg/kg b.w. p.o. twice daily), T and F (dosage, as above) or conservatively (0). Cows were treated days 11-14 pp in experiment 1 (T1, F1, TF1 and 0) and days 3-6 pp in experiment 2 (T2, F2, TF2 and 0). No placentas were removed manually. Jugular vein blood samples were collected twice daily for analyses of PGFM until day 20 pp. Twenty-two out of 24 cows had RP. All RP cows had bacterial endometritis. Tmax (time for max. level) and total AUC (area under the curve) for PGFM levels, mean (range), were 1.4 d (0.5-3.5) and 40000 d x pmol/L (21900-79700), n=22 for RP cows and 0.25 (0-0.5) and 16400 (14300-18500), n=2 for the non-RP cows. In all cows but one the PGFM profile showed an exponential decrease. Half lives (T) in days for the different groups were 1.3 (0.8-1.6, T1, TF1, F1 and 0, n= 14), 0.8 (0.7-1.1, F2, n= 3), 4.8 (4.1-5.4, TF2, n= 2), 2.7 (2.3-3.0, T2, n= 3) and 4 (3.5-4.5, non-RP, n= 2). Duration of the PGFM elevation was longer for groups T2, TF2 and non-RP than for T1, TF1, F1, F2 and 0. We conclude that the T for PGFM in our study reflects the rate of PGF₂ formation rather than the T for PGFM per se. This suggests a higher PGF₂ synthesis rate with a quicker decline in RP cows than in non-RP cows early pp. The effect of tetracycline treatment on PGFM synthesis remains to be elucidated.

KEY WORDS: retained placenta, PGF₂, flunixin, oxytetracycline