Doc

Doc was the dog of Meredith Grey, Addison Forbes Montgomery, and Derek Shepherd.

History
Doc was adopted by Meredith and came to live at her house to cheer up her and Izzie. Her roommates however (particularly George) didn't like him around the house so George delivered Meredith an ultimatum, him or the dog. Eventually Meredith decided to give the dog to Addison and Derek.

Cancer
After visiting the vet, Finn Dandridge, it was revealed that Doc had cancer, as a result, Finn put him down. Although Finn had the means of disposing him, Meredith did not want him thrown away like garbage and so Derek agreed to have him buried at the clearing by trailer, overlooking the water.

Notes and Trivia

 * When Meredith drowned in Elliot Bay, in the afterlife, she met a completely healthy, Doc.