Ovarian hemorrhage as the primary cause of hemoperitoneum in cycling and pregnant Miniature Horse mares.

The research examines the issue of hemoperitoneum in Miniature Horse mares due to nonneoplastic ovarian hemorrhage, highlighting the clinical manifestations of the problem and noting that reproductive tract assessment should be performed particularly in such cases.

Objective and Methods of the Study

• In an effort to determine if Miniature Horse mares are prone to hemoperitoneum caused by nonneoplastic ovarian hemorrhage and document the clinical characteristics of the disorder, a total of 51 equines with this disease, comprising 22 nonminiature mares and 9 Miniature Horse mares, were evaluated.
• The mares were identified from medical records at a tertiary large animal hospital, where definitive hemoperitoneum cases from 2012 to 2023 had been confirmed.

Signs of Hemoperitoneum

• The symptoms of hemoperitoneum in miniature mares ranged from lethargy and loss of appetite to colic, rapid heartbeat, and moderate to severe anemia, with the packed cell volume (PCV) measure ranging from 11% to 19%.
• Five of the studied miniature mares could not survive the condition and were subjected to necropsy.

Results

• The results of the study indicated that Miniature Horse mares were considerably overrepresented at 29% of all hemoperitoneum cases. Interestingly, no miniature stallions or geldings diagnosed with hemoperitoneum were identified during the study.
• In the case of nonminiature mares with hemoperitoneum, the root cause ranged from intestinal strangulation and suspected or confirmed neoplasia to peripartum uterine artery rupture, splenic trauma, ovarian hematoma, and spontaneous broad ligament hematoma.
• However, for miniature mares, necropsy confirmed that ruptured corpus hemorrhagicum and ovarian hemorrhage were the primary reasons associated with hemoperitoneum.
• For the remaining four miniature mares who managed to survive, no definitive cause of hemoperitoneum was identified despite extensive diagnostics. Nevertheless, one of these mares was treated for hemoperitoneum again after six years, where a corpus hemorrhagicum was suspected based on ovarian ultrasound.
• Two miniature mares who were in their first-trimester gestation and were undergoing treatment for hemoperitoneum, eventually gave birth to healthy foals.

Conclusions

• The research concluded that, although an ovarian hemorrhage is a relatively uncommon cause of hemoperitoneum in equines, it should still be considered a possible differential diagnosis for Miniature Horse mares, including those pregnant.
• A reproductive tract assessment should be carried out in cases of equine hemoperitoneum, with the focus being on miniature mares.