Effect of sodium cloprostenol and flunixin meglumine on luteolysis and thetiming of birth in bitches

At birth, the physiological role of prostaglandins in bitches is unclear. B itches were treated before parturition with either saline, the prostaglandi n analogue, sodium cloprostenol, or the prostaglandin synthetase inhibitor, flunixin meglumine. The animals were examined regularly to determine the o nset of parturition and a series of blood samples were taken to define the hormonal profiles before, during and after birth. Animals treated with clop rostenol whelped earlier than did controls. In addition, the prostaglandin F-2 alpha metabolite surge and decrease in plasma progesterone concentratio n and rectal temperature were earlier than in controls. Flunixin meglumine disrupted the normal 13,14-dihydro-15-keto prostaglandin F-2 alpha profile but did not abolish prostaglandin synthesis completely or delay the onset o f labour in treated animals. This study confirms that prostaglandins induce luteolysis and the onset of labour in the bitch. However, the partial inhi bition of prostaglandin synthesis does not prevent parturition.