Blood ammonia levels: A potential indicator of high-risk pregnancy in Thoroughbred broodmares

Exposure to high blood ammonia (hyperammonemia) interferes with gestation due to its detrimental effect on hormone levels, fetal development, the immune system, placental integrity, and fertility of broodmares. Increases in ammonia levels are dangerous and elusive, as damage may occur from earlier peaks, resulting in the trapping of ammonia in the amniotic fluid and then disappearing from the blood circulation before clinical symptoms are observed. Thus, it should be recognized early and treated immediately before complications arise. This study aimed to investigate if blood ammonia levels in broodmares are elevated at any time, representing a danger of adversely affecting conception and gestation. To achieve this, we conducted a random observational study using the immediate measurement of ammonia levels at the time of blood collection in 82 healthy pregnant Thoroughbred mares with a view to detection and treatment of elevated levels before there was a compromise to fetal health. We observed a flux in blood ammonia levels as the pregnant mares coped with any nitrogen overload. The findings from this study have the potential to improve the safety of pregnancy in broodmares for the horse breeding industry worldwide.