Evolution of the Concepts of Endometrosis, Post Breeding Endometritis, and Susceptibility of Mares.
Authors: Katila Terttu, Ferreira-Dias Graça
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Understanding post-breeding endometritis (PBE) requires recognising it as a physiological inflammatory response that, whilst protective in resistant mares, becomes pathological when dysregulated. Katila and Ferreira-Dias review how susceptible mares exhibit delayed and attenuated anti-inflammatory cytokine production compared to their resistant counterparts, allowing the initial neutrophilic influx triggered by spermatozoa to persist rather than resolve—a pattern compounded by anatomical and functional uterine clearance defects (particularly in older, multiparous individuals) that trap inflammatory mediators and bacterial contaminants. The authors present compelling evidence that endometrosis, long considered a separate degenerative condition, actually develops as a consequence of exuberant or prolonged inflammatory signalling, wherein sustained neutrophil activity and cytokine release drive pathological collagen deposition and extracellular matrix remodelling through prostaglandin interactions. This conceptual integration has immediate clinical implications: fertility management in susceptible mares should prioritise early detection of intrauterine fluid accumulation as a marker of clearance dysfunction, aggressive treatment of inflammatory episodes to prevent progression to chronic endometritis, and realistic breeding decisions based on age and reproductive history rather than viewing endometrosis as an irreversible, pre-existing pathology. The framework suggests that both conditions represent epigenetic consequences of repeated uterine insult, opening possibilities for targeted anti-inflammatory strategies and potentially identifying mares in whom breeding intervention carries prohibitive inflammatory burden.
Read the full abstract on PubMed
Practical Takeaways
- •Screen multiparous aged mares more vigilantly for post-breeding endometritis using ultrasound for intrauterine fluid accumulation, as they are at higher risk
- •Understand that endometritis and endometrosis are interconnected conditions influenced by age and uterine environment, requiring early intervention in susceptible mares to prevent permanent fibrosis
- •Recognize that individual mare susceptibility relates to their inflammatory response pattern rather than infection alone, affecting prognosis and breeding potential
Key Findings
- •Susceptible mares show delayed and weaker anti-inflammatory cytokine patterns compared to resistant mares following sperm arrival in the uterus
- •Delayed uterine clearance due to conformational defects, deficient myometrial contractions, and cervical relaxation failure is detected by intrauterine fluid accumulation and is a major susceptibility factor
- •Multiparous aged mares are more likely to be susceptible to post-breeding endometritis
- •Prolonged neutrophilia and cytokine release can cause permanent deleterious effects leading to endometrosis through collagen and extracellular matrix changes