Cystic endometrial hyperplasia-pyometra (CEH-P) complex is a progesterone-dependent disease that requires medical treatment in bitches intended for breeding. To test the efficacy and safety of a combined protocol and to assess the effect of age, stage of cycle, previous steroid hormone administration and parity on treatment, 29 bitches diagnosed with CEH-P complex were treated daily with cabergoline 5 microg/kg PO and cloprostenol 1 microg/kg SC for 7-14 days, along with supportive antibiotic and hydration therapies. Before treatment, and on Days 3, 7 and 14, all bitches were evaluated clinically and uterine horn diameter measured during trans-abdominal ultrasonography. Twenty-four of 29 bitches were cured by either Day 7 or 14. Nine bitches had mild digestive side effects. Clinical signs related to pyometra began to improve markedly as early as Day 2 of treatment. Uterine diameters decreased (P < 0.05) by Day 3 of treatment, and continued to gradually decrease, reaching normal size by Day 14. Relapses occurred in 6 of 29 cases. Pregnancy was achieved in one of the two young bitches bred after treatment. No significant relationships were found between success rate and age, stage of the estrous cycle, previous hormone administration or parity. Although no variables affecting treatment results could be identified, this combination of compounds was found to be an efficient and safe for treatment of CEH-P.