Are FURminator-style deshedding tools safe for my dog's coat?

It depends on the coat and how you use it. Specialist grooming subreddits we read repeatedly warn that aggressive deshedders can damage guard hairs or cause brush burn if used too hard, too often, or on the wrong coat type (notably double-coated working breeds and curly/wiry coats). Used sparingly, on a clean dry coat, with light pressure, most owners and many groomers report no issues. Avoid them entirely on doodles, poodles, and other non-shedding curly coats.