Dog Collars & Harnesses - Kmart Choose from leather or nylon collars and harnesses in a number of widths. Pair and dog collar with a flea and tick collar to protect your petâ€™s coat from unwanted pests. Choose from a wide selection of dog collars for pets of all sizes. Choose a stylish studded dog collar in red, tan or black for larger dogs. Cat Collars, Leashes, And Harnesses at Kmart Shop Kmart for a huge selection of affordable collars, leads, tie outs and harnesses for cats.