Danube Delta horse refers to a population of feral horse found in and around Letea Forest, located in the Danube Delta, between the Sulina and Chilia branches of Danube. About 3600 feral horses live in the Danube Delta, 2000 in the Letea nature reserve, where on one hand, they are among the last remaining "wild" (feral) horses living at large on the European continent, but are also deemed to be a threat to the flora of the forest, including to some plants on the IUCN Red List of Threatened Species.
Although feral horses have existed for hundreds of years in the region, their number greatly increased after the collective farms were closed down in 1990 and the horses belonging to them being freed. Today, the Letea population is not regulated and there are concerns that overgrazing is a looming problem.
The horses on Letea are black or bay, without white spots. They stand between 14.1 and 14.3 hands ( 1.45 to 1.50 metres (57 to 59 in)) and are of a strong build. They are of a different breed than the close by Sfântu Gheorghe breed. They are not of a riding horse build, but are built like working horses of the Nonius type.
In 2002, some of these horses were captured and transported to Italy and slaughtered. Some organizations objected to removal, holding that the horses had value in being adapted to the location and possessing natural social behavior. Another push for removal and slaughter began in 2009, but horses cannot be currently removed from the area because a number of animals carry equine infectious anemia. Therefore, according to Romanian regulation, they are not allowed to be taken out of the quarantine area. Currently, there is an ongoing project, in collaboration with the World Wide Fund for Nature, seeking to find a way to remove these horses. While some organizations object to total removal and advocate for some animals to remain, others are attempting to find a different preserve for the horses to live.