Mare reproductive loss syndrome

Mare Reproductive Loss Syndrome (MRLS) is a disease that affects mares, causing them to lose their foals either late in pregnancy or shortly after birth. The syndrome was first identified in the Bluegrass region of Kentucky in the spring of 2001, and has since been reported in other parts of the world.

Causes[edit]

The exact cause of MRLS is unknown, but it is believed to be associated with the ingestion of Eastern tent caterpillars. The hairs of these caterpillars can penetrate the intestinal wall of the mare, allowing bacteria to enter the bloodstream and cause an infection in the placenta.

Symptoms[edit]

Mares affected by MRLS may show no outward signs of illness until they abort their foals. The foals that are born alive often die within a few days due to septicemia or other complications. Other symptoms may include mild colic, decreased appetite, and depression.

Diagnosis[edit]

Diagnosis of MRLS is based on the presence of characteristic lesions in the placenta and the exclusion of other causes of abortion. Laboratory tests can be performed to detect the presence of bacteria in the placenta and foal.

Treatment and Prevention[edit]

There is no specific treatment for MRLS. Management strategies to prevent the syndrome include removing mares from pastures where Eastern tent caterpillars are present and providing supportive care to affected mares and foals.

Impact[edit]

The economic impact of MRLS is significant, particularly in regions where horse breeding is a major industry. In 2001, the syndrome resulted in the loss of an estimated 30% of the foal crop in Kentucky, with an estimated economic loss of $336 million.