'Milk-drop syndrome of ewes': Investigation of the causes in dairy sheep in Greece

“Milk-drop syndrome of ewes” is defined as a pathological entity at flock level and a syndrome characterized by reduced milk yield of lactating ewes, with no clinical signs specific to a disease. Concurrent presence of the following two criteria was necessary to diagnose the syndrome in a flock: (i) >30% reduction of flock milk production and (ii) >25% of ewes affected, each ewe with >25% reduction in milk yield. An investigation into the causes of the syndrome was carried out in 22 flocks in Greece. Reduction in milk production in the flocks ranged from 30% to 90% and proportion of affected animals ranged from 27% to 100%. Subclinical mastitis was the primary cause of the syndrome (11 flocks as sole cause/3 flocks co-existing with other disorders). Contagious agalactia was another important cause of the syndrome (3 flocks as sole cause/1 flock co-existing with other disorders). Other causes of the syndrome included: inappropriate feeding regime (2/4 flocks), small ruminant lentivirus infection (2/2 flocks), ruminal acidosis (0/3 flocks) and increased burdens of gastrointestinal nematodes (0/1 flock).