PHILADELPHIA (CBS) — It was a sad day for the Trenton Thunder and their fans.

Team Bat Dog Derby, who was battling cancer, passed away on Saturday just before his 10th birthday.

“Derby was one of the biggest parts of our identity in the nine years of his life and it breaks my heart to share this news with our fans ahead of our 25th season,” said Thunder GM/COO Jeff Hurley. “His presence at our games and in the community was massive and every person and dog that interacted with him will miss him dearly.”

Derby made his on-field debut in April of 2008.

Derby became a dad on Dec. 15, 2013 with the birth of his son Rookie and daughter Mickie.

The team urges fans looking to send their condolences, to make a monetary donation in his name to Trenton Thunder Charities or to Delaware Valley Golden Retriever Rescue.