If the mat isn't too tangled, spritz it with detangler solution, then brush it loose with a comb. Slowly detangle the hair on the outside of the mat (where it isn't twisted) without pulling. If the mat didn't come out with a comb, use a mat rake to cut through it. Because this equipment includes sharp tines, use caution when using it; you want to relieve your dog's mat pain, not make it worse by cutting or scratching her with the rake.