What is "polkan"

Polkan or Palkan ( Russian: Полка́н or Палкан, from the Italian Pulicane) is a half-human, half-horse (in some variants, half-dog) creature from Russian folktales which possesses enormous power and speed. He appears first as the enemy of the hero Bova Korolevich but after a battle becomes his loyal friend and ally. Polkan is originally based on Pulicane, a half-dog character from Andrea da Barberino's poem «I Reali di Francia», which was once popular in Slavonic world in prosaic translations.