Mice and rats: feeding a healthy diet

The mice we keep as pets are the same species as the house mouse. They live alongside human beings nearly all over the world, eating what they can find. Rats are designed to eat plants, e.g. seeds, roots, nuts and fruit. The cheek teeth of the rat are more like our own than the teeth of rabbits or guinea pigs. They don’t keep growing throughout the animal’s life, but like ours, they erupt when the animal is young and have to last it all its life. The incisors are constantly growing and wearing against each other to form the characteristic chisel shape. Rats like to gnaw to keep their teeth in trim and because their natural diet would demand it; do not chop or grate vegetables too finely but let them gnaw pieces off themselves.

Mice are ‘omnivores’, which means that, like us, they have evolved to eat mainly vegetable matter, but to keep in good health require some food of animal origin as well. The best commercial small mammal mix to feed your mice would be one that is sold in sealed packets, so it remains fresh, and that contains some protein of animal origin (look at the label on the back of the packet for this information).

Fresh food

Mice will eat fresh food too; they will eat almost anything, but to keep them in the best of health feed a selection of bits of fruit and vegetables each day – try different ones to see what their favourites are. You can also feed things like dried fruits, pieces of toast, pasta and rice. Some mice like sweet things like fruit yoghurts, but these should be small amounts and only occasionally to prevent obesity.

Cheese and meat

Mice are famous for being mad about cheese, although people who don’t like mice find that they catch more if they bait a trap with bread instead! However, you can certainly try your mice with cheese and meat. Another good source of protein is eggs.

Foods to avoid

To keep your mice in good health, you should avoid feeding too much food containing lots of sugar, for example sweet biscuits or chocolate. You should also avoid feeding anything that is high in fat.

Rats are ‘omnivores’, which means that, like us, they have evolved to eat mainly vegetable matter, but to keep in good health require some food of animal origin as well. There are some very good rat mixes on the market. You should always supplement your rat’s diet with a good selection of fresh food including fruits and vegetables, pieces of hard-boiled egg, cheese, they will even eat the dregs from your yoghurt pot!

Commercial mixes

Firstly look at the label; the protein level should be in the mid- to high-teens (15-18%), and some of that should be animal protein. Mixes that are predominately seeds and peanuts will make the rat fat but unhealthy. Make sure the pack is within its sell-by date. Secondly look at the mix; it should smell fresh and not be dusty. It is better to buy a packaged mix rather than a loose mix from a large bin – this will ensure freshness.

A good commercial mix has been well thought out and provides all the nutrients the rat needs for a long and healthy life. Many pet rats are fed on the same food as their owners, and seem to be remarkably healthy. Some people even alter their shopping habits to keep their rats on a healthy diet! A rat that starts the day with a bowl of cereal, some toast and a bit of fruit, and has bread, fruit and vegetables to nibble during the day, and shares your supper at night could live a long and healthy rat life!


Some owners feed their rats the sort of pellets fed to laboratory rats. They need to be fit and well, and the pellets they are fed provide a balanced diet.


If you know a treat would be good for you, it will also be good for your rat. So, if you eat a healthy diet, anything you consider to be healthy for you will be healthy for your rat. Try to avoid food that is very sweet, fatty or salty. However, it is very easy to produce a fat rat as they are so much smaller than us – one peanut provides a great proportion of their calories for the day. Seeds and nuts should therefore be kept to a minimum of 1 or 2 peanuts and sunflower seeds per day.

Can poor diet lead to disease in rats?

Obesity in pet rats is a known problem. Plenty of exercise with limited access top chocolate biscuits and high fat seeds will prevent this problem. Wild rats have evolved to be survivors, and can survive even on a poor diet, but there is no doubt that a good and varied diet makes for a healthy pet rat, with increased resistance to disease.