Antibiotic-Free Management of Canine Pyometra With Aglepristone: Endocrine Effects and Post-Treatment Vaginal Hyperplasia.

This study evaluated the clinical efficacy of aglepristone for the management of canine pyometra-either as a sole therapy or in combination with different antibiotic regimens-and investigated the association between aglepristone dosing and the occurrence of vaginal hyperplasia during the subsequent estrous cycle. Eighty-seven intact bitches diagnosed with pyometra were enrolled and divided into two experiments. In Experiment I, 57 bitches were randomly assigned to three treatment groups (n = 19/group): (1) AGL, aglepristone alone; (2) AGL-CEF, aglepristone plus ceftriaxone; and (3) AGL-CEF-MET, aglepristone plus ceftriaxone and metronidazole. Clinical examinations and haematological and biochemical profiles were assessed every 48 h for 15 days. In Experiment II, 30 bitches were treated with aglepristone using two protocols: AGL 4X (10 mg/kg s.c. on Days 0, 1, 8 and 15) or AGL 2X (10 mg/kg s.c. on Days 0 and 1). Incidence and severity of vaginal hyperplasia, as well as post-treatment reproductive performance, were evaluated during the subsequent oestrus. All three treatment protocols achieved clinical resolution of pyometra-including the aglepristone-only group-with normalisation of leukocyte counts and serum biochemical markers. In Experiment II, vaginal hyperplasia occurred in 53.3% of bitches in the AGL 4X group versus 7% in the AGL 2X group. Grade III hyperplasia was associated with pyometra recurrence and reduced pregnancy rates. Overall pregnancy rate in Experiment II was 80%. These findings indicate that aglepristone is an effective, fertility-preserving treatment for canine pyometra, even when administered without systemic antibiotics. However, high-dose or prolonged administration may induce oestrogen-mediated adverse effects such as vaginal hyperplasia and disease recurrence. A reduced dosing regimen appears safer while maintaining equivalent clinical and reproductive efficacy.