I do not believe you would capitalize "golden retriever" . Yes it's a noun , but only proper nouns are capitalized .
“Constance Culmington, he reflected to himself, was exactly the sort of woman who would buy an island and surround herself with mystery! Nodding his head in gentle approval of his logic, Mr. Justice Wargrave allowed his head to nod... He slept..." Chapter 1, pg. 3
To explain some of the obstacles she faces.
