Blood horses resembled sleek, lithely muscled horses about 6 ft (1.8 m) tall at the shoulder and weighing approximately 1,250 lb (567 kg). Blood horses also had massive bat-like wings with a 20 ft (6.1 m) wingspan. They had a jet-black coat and small, pink eyes. The nostrils were oddly flared. Blood horses had hooves that closely resembled talons, and they had sharp carnivore teeth. The tail was thin and hairless.
Blood horses could see by emitting high-frequency sounds for up to 120 ft (37 m),. However, a silence spell or effect could negate the ability, forcing them to rely on their poor (only 20 ft (6.1 m) at most) darkvision. They could also detect good at will.
Blood horses were capable of making an ear-piercing screech to partially deafen and stun potential prey within 20 ft (6.1 m) of the blood horse.
While flying or walking, a blood horse could easily carry up to 300 lb (140,000 g). They could less easily carry up to 600 lb (270,000 g), or as much as 900 lb (410,000 g) with great effort.
Blood horses were carnivores that would eat almost any prey, but they preferred the taste of fresh blood, and were known to pin and drain enemies during combat. They were fickle, cruel creatures that typically lived in warm or temperate forests, hills, and plains.
Blood horses were known to live alone, in pairs, or in herds of 5-8 individuals. They matured at the same rate as normal horses.
Historically, blood horses were originally created by another being and did not naturally appear on Toril. Their progenitor was a former Red Wizard of Thay that later joined the ranks of the Zhentarim.