Maera was the dog of the Athenian hero Icarus, who had been presented with the vine by Dionysus.
The latter had also taught Icarus the art of grape-harvesting, pressing him to spread the habit of wine-drinking amongst his neighbours. Unfortunately, when invited to a banquet, Icarus' friends got drunk, thought he had intended to poison them, and killed him in revenge.
Maera, with her barking, attracted the attention of Icarus' daughter Erigone. When she saw her father' body, distraught she killed herself, and Mera stood by their bodies, until she herself died of grief.
Dionysus, touched by such fidelity, brought her to heaven as a constellation.