Fescue that is infected with the endophyte cannot be recognized with plain vision. However, it can be identified upon microscopic examination of a forage sample. There is no test to identify the endophyte in the blood of the mare or foal. Once established, it is extremely difficult to eliminate the endophyte from pastures. The fescue that is infected with the endophyte is much hardier than the non-infected fescue.
Prolactin is a hormone that is integrally involved in mammary gland development and lactation.
Another sign seen in fescue toxicosis is prolonged gestations. Mares will often carry their foals for 13 or 14 months. This is due to a lack of readiness for parturition by the mare. Her pelvic ligaments and muscles do not relax properly and since she will already be delivering a larger foal, problems with dystocia are common. The placenta can also separate early in mares grazing endophyte-infected fescue which can lead to a higher incidence of retained placentas.