The Efficacy of a 3β-Hydroxysteroid Dehydrogenase Inhibitor for the Termination of Mid-Term Pregnancies in Dogs

Abstract

Progesterone (P4) is the only hormone needed to maintain pregnancy in dogs. Therefore, a competitive inhibitor of 3β-hydroxysteroid dehydrogenase (3β-HSD) could be a safe and effective option to terminate pregnancy by inhibiting P4 synthesis. To address this hypothesis, we investigated the efficacy of trilostane (TRL), a competitive inhibitor of 3β-HSD, in terminating pregnancy in dogs. Twenty-one dogs between days 30 and 38 of pregnancy were randomly assigned to one of two treatment groups (trilostane (TRL) and aglepristone (AGL)) and an untreated control (CON) group (n = 7 dogs each). Fetal heart rates (FHRs) (measured at 12 h intervals) and serum P4 concentrations (measured at 6 h intervals) were evaluated. The pregnancy termination rates were 0% and 100% in the TRL and AGL groups, respectively. The decrease in the FHR in the TRL and AGL groups was significantly lower than that observed in the CON group. There was a marked decrease in P4 concentrations in the TRL group 6, 54, and 102 h after the initiation of treatment. The luteal expression of StAR appeared to be weaker in the AGL group than the CON group. In conclusion, although a treatment-induced decrease was observed in plasma P4 concentrations, a seven-day TRL treatment alone was not effective in terminating pregnancies. Further studies are needed on the effects of the prolonged administration of TRL with varying doses and frequencies for the termination of mid-term pregnancy in dogs.

Opinions of Turkish veterinarians on the termination of unwanted pregnancies in dogs

“…All these aspects result in a challenging ethical decision‐making process for veterinarians 4,6 . To the knowledge of the authors of the present study, apart from a few literature reports suggesting pregnancy termination to be unethical after day 45 of the gestation process in dogs, 26,27 there are no legislative arrangements, detailed resources or discussion background available for this topic in Turkey. Given that the issue is not directly or comprehensively regulated in legislation, the responsibility weighs heavily on the veterinary profession 4,6 …”

Decidual cells and decidualization in the carnivoran endotheliochorial placenta

“…Pharmacological termination of pregnancy for the control of reproduction has been a growing field of research in veterinary medicine. Drugs intending to block different molecular targets that support pregnancy are used in bitches and queens, and the success of the clinical procedure relies on several factors ( Fieni et al, 2006 ; Georgiev and Wehrend, 2006 ; Georgiev et al, 2010 ; García Mitacek et al, 2012 ; Karakas Alkan et al, 2020 ; Kowalewski et al, 2020 ; Binli et al, 2022 ). Data regarding the sources (including decidual contribution) of relevant substances, namely, progesterone, prolactin, and prostaglandins, and the understanding of their functions and dynamics of secretion along pregnancy, are required for the improvement of those methods.…”

Novel approaches in IBD therapy: targeting the gut microbiota-bile acid axis

“… 214 Similarly, a competitive inhibitor of 3β-hydroxysteroid dehydrogenase (3β-HSD) may terminate pregnancy by inhibiting the synthesis of progesterone (P4). 215 To the best of our knowledge, no inhibitor of HSDH for IBD treatment has been discovered to date. Our knowledge regarding the role of the bai gene is also limited.…”