Home: Feeding

What NOT to Feed Mice and Why

By Cait McKeown

  • Citrus fruits (cause the runs)
  • Peanuts (They are fattier than other nuts and may provoke a skin reaction in susceptible mice, although a few peanuts in the mouse’s food mix may be ok. I would give them complete with shell, which the mice will also eat.)
  • Chocolate (can be toxic to rodents in large amounts)
  • Unwashed fruit/vegetables (These may contain pesticides. A simple rule is not to feed your mice anything that you wouldn't eat yourself.)
  • Wheat (can cause skin problems in susceptible mice)
  • Cheese (despite the stereotype of mice, cheese is not good for them and many don't like it!)
  • Milk (Only offer milk products (kitten milk replacement formula) if there is a medical reason or the mice are being hand-reared. Milk is unnecessary and can cause health problems in both the short and long term.)
  • Lettuce (causes diarrhoea) *Too many watery vegetables, such as lettuce, can cause runny stools.
  • White millet (this is too fatty, use yellow millet instead which is sold for birds)
  • Maize (see wheat)
  • Fizzy drinks (can be fatal - see below)


When feeding greens (i.e. fruits and vegetables) make sure that you do not give your mice too much as this can cause them to get diarrhoea. Crunchy vegetables like carrots and fruit like apples do not tend to cause this problem. DO NOT feed your mice lettuce - it can make them ill. Most other fruits and vegetables are ok, but always check if you are unsure. Citrus fruits are another thing to be avoided as they tend to give mice the runs - there are plenty of alternatives, so use these instead. When feeding greens remember that they are best fed raw to preserve the vitamins and minerals, but always wash and peel them before giving them to your pets - in other words, prepare them as you would if you were going to eat them. If your mouse has diarrhoea then a couple of days of abstinence from greens may clear this up.


If you are feeding bread to your mice you may want to let the bread dry out first. This is because some breeders say that their mice react badly to the enzymes in the bread, giving them spots. However many owners frequently feed bread to their mice with no problems, including myself. If you want to give extra nutrients to a sick mouse, bread soaked in stock or gravy may be a good solution.


It seems to be a generally held belief that chocolate can be toxic to mice and rats, although I have never seen any research to support this. But it is best to be safe, so if you want to give your mouse a treat, use special mouse chocolate drops or another kind of treat.

Fizzy Drinks

Mice and rats cannot burp (or pass wind I suppose) so they do not have the capability to get rid of excess gas that may result from drinking carbonated drinks. This build up of gas can be dangerous and even a small amount can kill a small animal like a mouse, so please don't give your mouse fizzy drinks. They will be much happier drinking water and much safer too.

Mice Can't Be Sick

Mice cannot physically be sick so it is impossible for them to get rid of bad food if they happen to eat any. This means that it has to go all the way through their digestive system and will do whatever harm it may be able to do on the way. This is also the reason why rat/mouse poisons work - once the animal has eaten the poison they can't get it out of their system and it does its job. Because of dangers like this, mice usually eat a small amount of a new food and then wait a while to see if they feel ill before eating any more. If after a while they do not feel ill then they can reasonably assume the food is safe to eat and go back to it.


There has recently been some worry about giving mice and rats too much corn in their diets. The reason for this is that corn can contain certain contaminents that may cause illness in rodents - see the RMCA article on the subject for more information.

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