CONCLUSION

This retrospective study demonstrated that hypoluteodism in predisposed dog breeds, particularly SS, follows a consistent temporal pattern, with 79.3% of cases developing luteal insufficiency during weeks 5–6 of gestation. Implementation of serial P4 monitoring and timely intervention with a low-dose MPA protocol resulted in successful maintenance of pregnancy to term in 86.2% of cases. Among the 25 successful pregnancies, 110 live puppies were delivered, of which 94.5% survived to weaning. Importantly, no evidence of virilization in female offspring, premature labor, maternal diabetes mellitus, mammary hyperplasia, mammary tumors, or lactation failure was observed, supporting the favorable maternal and neonatal outcomes associated with the treatment strategy.

A major strength of this study is that it represents one of the largest documented cohorts of bitches with hypoluteodism managed using systematic serial hormonal monitoring and a standardized timed-withdrawal protocol. Furthermore, the study provides novel evidence supporting the existence of a breed-associated critical period for luteal failure in SS and demonstrates the feasibility of using a low-dose MPA regimen under intensive clinical monitoring.

Future prospective controlled studies involving larger and more diverse canine populations are warranted to validate the proposed critical window, investigate the underlying mechanisms responsible for breed susceptibility, and compare MPA with alternative progestin therapies. Further research evaluating long-term reproductive outcomes and offspring development would also provide valuable information regarding the safety of hormonal intervention.

Overall, the present findings indicate that hypoluteodism in predisposed breeds is characterized by a predictable period of luteal vulnerability during mid-gestation and that a carefully monitored low-dose MPA protocol with strategic prepartum withdrawal represents an effective and practical approach for preserving pregnancy and optimizing reproductive outcomes. These results provide clinicians with an evidence-based strategy for managing canine luteal insufficiency and contribute to the refinement of reproductive medicine in dogs.