A protective boot for the ankle of a horse includes a flexible panel with a middle portion and two opposing side portions extending outwardly therefrom. The middle portion is suitable for abutting the digital flexor tendon of the horse. The two opposing side portions are suitable for wrapping around the ankle of the horse. A slot is provided which extends along the digital extensor tendon and is defined by the two opposing side portions. A cup is formed at a bottom of the middle portion, the cup receiving the proximal sesamoid bones of the ankle of the horse. Lateral grooves axe provided, which are positioned over the palmar digital veins of the horse. The flexible panel includes an outer foam layer and an inner heat-absorbing layer. A reinforcing elastic wrap is removably affixed around the flexible panel.
