This study evaluated a new method for mid-gestation termination in the bitch, which consisted of ultrasound-guided administration of a single dose of d-cloprostenol, a PGF(2alpha) analogue, into a single gestational sac. Effects on serum progesterone concentration (P(4)) were also investigated. The study was performed between days 28 and 35 of gestation on 15 privately owned crossbred bitches, randomly divided into two groups: group A comprised 10 bitches treated with 15 microg per head d-cloprostenol diluted in 0.8 ml sterile saline (final volume 1 ml); group B comprised 5 bitches treated with 1 ml of sterile saline solution (0.9% NaCl), administered in the same way. In all bitches of group A, fetal death was successfully induced within 5 days (mean: 3.1 days, S.D. 1.2) with no clinical or behavioural complications. Mild adverse effects were observed in two bitches, each weighing less than 10 kg, including salivation, defecation and hyperventilation, which disappeared within 15 min. None of the subjects in group B aborted within 10 days post-treatment. In group A, P(4) declined 2.8 days before pregnancy termination to a mean value below 30 nmol/l (S.D. 2.9 nmol/l). However, two bitches showed a higher concentration of P(4) throughout the sampling period. Our study demonstrates that intra-vesicle administration of a single low dose of D-cloprostenol is an effective and safe technique for induction of abortion, which offers an additional option for termination of unwanted pregnancy in the mid-gestation bitch.