The customary Nandi bull at the Murappanadu Kailasanathar Temple in Tirunelvelli district in Tamil Nadu has the head of a horse. This Shiva temple is one of the Nava Kailasam temples.
As per the story associated with the temple, a king the region had a daughter with the face of a horse. He offered prayers to Shiva to find a relief. Shiva one day appeared in the dream of the king and asked him to take a holy dip in Thamiraparani River at Murappanadu and offer prayers to the Shivling there.
The king soon performed all that Shiva told in the dream. Soon the princess got back the human face.
It is believed that Shiva asked Nandi to take the face of a horse to cure the princess.
Nandi with horse head faces the main Shivling worshipped in the temple.