 There is a relatively small variety of coats in relation to the number of colors and markings , and not all are internationally standardized . The most common type is the normal or standard , which is allowed variance in coarseness between the sexes ; males have a coarse , thick , rough coat , while females ' coats are softer and finer . Other standardized coats include : rex , in which all the hairs are curly , even the whiskers ; velveteen , a softer variation of the rex ; satin or silky coat , which is extra @-@ soft and fine , with a sheen ; and Harley , characterized by wispy long straight hairs . Remaining coat types are not defined by the hair itself , but rather by the lack of it , such as hairless rats . 
