In Gesta Danorum, book 7, Saxo Grammaticus tells of a Gunnar, "the bravest of the Swedes" who invaded Norway and relished killing rather than pillaging.
Hversu Noregr byggðist and Hákonar saga góða refer to a king named Eysteinn Illráði who had a dog as subking.
For three years Saurr was treated regally, with a collar of gold, courtiers, a throne, and a mansion - and routinely signed paw-print decrees - until one day wolves broke into his fold and tore him to pieces.
This Erpr was the skald of the Swedish king Eysteinn hinn illráði, which puts the events in the early 9th century.
The source used for the genealogical information and name spellings is the English translation provided by Mischa Hooker of Augustana College.