 There is some evidence that spayed female rats ( " does " ) are less likely to develop mammary and pituitary tumors than non @-@ spayed females . Research into prevention of common diseases and health issues in rats is on @-@ going . Dietary changes are among the main suggestions for improved health and longevity in fancy rats , such suggestions included are feeding rat @-@ friendly <unk> in moderation to reduce the risk of cancers , heart disease and stroke . 
