The Deer King: Yuna and the Promised Journey

Van is the head of a group of soldiers who expected to die fighting for their lands against a large empire looking to incorporate their home into its kingdom.

However, instead of dying, Van is taken as a slave and thrown into a salt mine.
One night, a pack of strange dogs attacks the salt mine, and a mysterious illness breaks out.During the attack, Van takes the opportunity to escape, and he meets a young girl.
Elsewhere, rumor is spreading that only immigrants are coming down with this mysterious illness.The medical scientist Hossal risks his life to search for a cure. Doctors also study a father and child who seem to have survived the illness.

(Source: Anime News Network)