The British singer was walking her Labrador Retriever Phoebe in London on Monday (04Feb13) when the pooch ran away.
Bunton took to Twitter.com to urge fans to get in contact if they heard of sightings of the canine and she offered a reward for the pet's safe return.
However, Bunton updated her followers on Wednesday (06Feb13) to reveal her pet has met with a tragic end.
She writes, "To all the amazing people who supported us at this horrible time. Our precious phoebe has been found and its (sic) terrible news, we are devastated."
Former Boyzone star Ronan Keating passed on his condolences, tweeting, "I'm so sorry Emma... Just heard."