The International Collating Centre, Newmarket, England, and other sources reported the following disease outbreaks during the fourth quarter 2005.

Cases of abortion caused by equine herpesvirus-1 (EHV-1) were reported from New South Wales, Australia, Ireland, and the United Kingdom, with sporadic cases reported from Argentina, France, Japan, and South Africa. Neurological disease attributable to EHV-1 infection was confirmed among Thoroughbred racehorses at Turfway Park Racetrack in Northern Kentucky at the end of December. Two racehorses and an outrider pony developed severe clinical signs resulting in euthanasia. During January 2006, EHV-1 infection was also confirmed at a Western Kentucky training facility, at two racetracks and a farm in Maryland, and at a racetrack in Pennsylvania. Several horses were euthanatized after they developed severe signs of neurological disease.

Respiratory disease attributable to EHV-4 was confirmed among groups of horses in Argentina, France, and the United Kingdom. Respiratory disease attributable to equine influenza was confirmed among groups of horses in France and the United Kingdom.

Turkey reported an outbreak of leptospirosis infection, causing mild clinical disease on a Thoroughbred farm. Mild clinical cases of piroplasmosis infection were reported on several premises in Switzerland and on one premise in Turkey. Strangles was diagnosed on a farm in New South Wales, Australia, on several premises in Ireland, and in South Africa and Switzerland