What is "shvan"

Shvan, a Sanskrit word meaning a dog, finds repeated references in Vedic and later Hindu mythologies, and such references include the following:

• The Apsara of Indra, a Vedic god, is named Sarama, and it is mentioned in the Rig Veda. Its offspring became the watch dog of Yama.
• Yudhishthira, one of the Pandavas, insisted that he be allowed to enter Svarga ( Heaven) with the Shvan which had followed him from their advent to Swarga where in Yudhishthira lost his brother and wife, only Shavana followed him when the devadhootha came in front of Yudishtara to take him to Svarga the dog transformed itself into Yama.
• Deities like Rudra, Nirriti and Virabhadra are associated with dogs.
• Shiva, in his aspect as Bhairava, had a dog as a vahana (vehicle) (mentioned in the Mahabharata).
• Khandoba, a deity, is associated with a dog on which he rides.
• Dattatreya is associated with four dogs, considered to symbolize the four Vedas.