Sporadic milk drop syndrome in dairy cows is being reported with increasing frequency in the UK. Although the syndrome is associated with a variety of infections, in many herds no infectious or metabolic cause can be found. Clinical signs include total or partial milk loss, dullness, inappetance and weight loss; pyrexia and respiratory signs have been reported. The condition is most common during the first 3 months of lactation and typically occurs in the winter. Recovery is within 7-10 days, with or without treatment, and relapses may occur. A nutritional component has been suggested and in most affected herds maize silage is fed.