Sodium cloprostenol administered at a continuous low dosage induces polydipsia and suppresses luteal function in early dioestrous bitches

The aim of this study was to determine whether sodium cloprostenol administ ered at a continuous low dosage induced luteolysis and polydipsia in early dioestrous bitches. Sodium cloprostenol was administered subcutaneously to greyhounds at doses of 4.04-5.19 mug/kg/day (treated group, n = 5) or 0 mug /kg/day (control group, n = 5) delivered by mini-osmotic pumps for 7 days. The treated bitches and two of the control bitches were in early dioestrus (Days 5-14, and 6 and 10, respectively) when the mini-osmotic pump was inse rted (Day 0). Concentrations of plasmatic progesterone were measured in dio estrous hitches each day from Day -2 to 7, and then weekly until Day 90. Da ily intake of water was ascertained in all bitches from Day -2 until Day 10 , and their weight was measured on Days -2, 6 and 13. Biochemical analyses on plasma For concentrations of urea and glucose, and urinalyses were perfo rmed on all bitches before (Day -1), during (Day 4) and after treatment (Da y 10). Concentrations of plasmatic progesterone declined dramatically and r apidly in treated bitches after Day 0 to <2.9 ng/ml but were not similarly affected in the dioestrous control bitches. However, in three of five treat ed hitches, concentrations of plasmatic progesterone increased to > 1ng/ml in the period from Day 10 to 90 indicating that luteolysis was incomplete. All treated bitches were polydipsic (intake of water > 100 ml/kg/day) for 2 -6 days during the period of treatment, and for 0-2 days immediately after treatment (Days 7 and 8). One control bitch was polydipsic on Days -2, -1 a nd 0. The treated bitches were also polyuric since they were hyposthenuric (<1.007, n = 4) or isothermic (1.010. n = l)on Day 4, their weight did not increase and no gastrointestinal or respiratory effects were observed. The control bitches were always hypersthenuric when measured during and after t reatment (>1.021). Biochemical analyses of plasma and other data obtained f rom urinalyses did not reveal any differences between groups. This study in dicated that sodium cloprostenol administered at a continuous low dosage in duced polydipsia and suppressed luteal function in early dioestrous bitches . (C) 2001 Elsevier Science B.V. All rights reserved.