Each of these species is extremely clean, grooming themselves and each other as instinctual behavior and as an important activity during their awake time. Gerbils need little grooming. They keep themselves and each other scrupulously clean. Being desert animals, native to arid regions of northeastern China and eastern Mongolia, they excrete very little urine and have hardly any odor. Gerbils need to be brushed occasionally with a small bristle brush or soft toothbrush.
Guinea pigs require grooming once or twice a week.
English smooth-coated guinea pigs are brushed from head to tail, in the direction the fur grows, with a small soft bristle brush or toothbrush to remove dead hair from the coat. Hamsters spend a great deal of their waking time grooming themselves thoroughly with their tongues, their teeth and paws to keep their fur in good condition. They will contort themselves into unusual positions to reach all parts of the body. Shorthaired hamsters need to be brushed occasionally while longhaired types need more frequent grooming with a small bristle brush or soft toothbrush. Mice and rats are extremely fastidious.