The phrase "undercoat rake" refers to a tool used for grooming pets, particularly those with thick fur. It helps to remove the loose and dense undercoat of fur, leaving behind a smoother and healthier top coat. Full definition
Invest in a good undercoat rake to help loosen the dropped fur from the protective top coat. (blog.pawedin.com)
Another key to a great bath on double - coated breeds is to run a brush, comb or undercoat rake through the coat when the dog is wet and soapy. (petbusiness.com)