Rat & Mouse Nutrition

Rat & Mouse Nutrition

Rats and mice are omnivorous, which means that they eat both plant and animal material.

Good nutrition is vitally important for long term health and well-being. Rats and mice thrive when fed on a diet of nutritionally balanced pellet and grain chow such as Topflite Rat and Mice Mix: a commercially available base diet that contains essential nutrients, vitamins and minerals. With their high metabolic rates, it is important that rats and mice have access to food at all times. Mice will eat approximately 3-5 grams of food per day and rats approximately 15-20 grams per day. Food is best provided in chew-resistant dishes that are either attached to the sides of the cage or that are heavy enough that they cannot be tipped over (e.g. a ceramic bowl).

You can also offer your rat or mouse small bite-sized amounts of well -washed fruits and vegetables such as peas, broccoli, carrots, apples and bananas. Remember to remove any uneaten fruits and veges after 4 hrs to prevent spoilage. Mice in particular love to ‘stash’ their food, usually close to their sleeping area. Try to locate your mouse’s favourite hiding place and check regularly to ensure that the food he/she has hidden hasn’t become mouldy or spoiled. Avoid sudden changes to the diet as this can cause diarrhoea. Introduce new foods gradually.

Like humans, rodents will eat when they are bored and therefore can be prone to obesity. They love foods which are high in fat and sugar. For this reason, treats should only be given occasionally. Instead of table scraps, you can offer commercially prepared supplements such as Rat and Mice Topflite Treats; a blend of the best quality seeds and pellets available, purposely designed with rats and mice in mind!

Rats and Mice have long front incisor teeth that grow continuously and need to be worn down (the word rodent comes from the latin word rodere meaning ‘to gnaw’. Rats and mice need a continual supply of safe chew toys to gnaw on in order to wear down their teeth, eg. wooden chew sticks. The safest toys to use are those purchased from a reputable pet supply store.

An interesting feature of both rats and mice is that they are coprophagic. They will eat some of their own fresh faeces (essentially digesting their food twice!). This is a normal, healthy behaviour that actually provides additional vitamins. Rats and mice that are unable to consume their faeces can become nutritionally deficient and develop health problems.

To be given daily:
Rats and Mice should have constant access to clean drinking water. Because the majority of their food is dry (e.g. pellets and grains), they will have a high demand for water. Mice will consume approximately 15ml water per 100g bodyweight per day. Rats will consume approximately 10ml water per 100g bodyweight per day. Sipper bottles are a better option than bowls – water in open bowls can quickly become soiled or be spilled. It is best to provide 2 bottles per cage, just in case one of the sipper tubes becomes clogged (check the sippers regularly to ensure they are working properly). Remember to thoroughly clean the sipper bottles regularly. Algae and bacteria can build up inside a dirty sipper tube and may cause illness. Use a mild solution of dish detergent in water, scrub with a clean brush, and then rinse thoroughly.

Foods to avoid:
Spoiled or mouldy foods, processed foods, ‘gassy’ foods: eg. carbonated drinks (mice and rats can’t burp), caffeinated drinks, licorice, avocado, rhubarb, uncooked beans, onions, blue cheese, raw/green potatoes or potato skin. Sticky foods such as peanut butter, toffee, lollies, caramel and rolled fruit snacks can cause choking (rats and mice are unable to vomit). Remember, if you are unsure if a particular food is safe for your pet to eat, it is wise to avoid feeding it altogether.

Whether or not to feed chocolate to rats and mice is controversial. Studies have shown that rats and mice are less susceptible to chocolate poisoning than cats and dogs, but that chocolate consumed in high doses can still cause death (especially dark chocolate). Chocolate is therefore best avoided.

Rats are highly inquisitive and have been known to ‘taste’ almost anything they get their teeth on. For this reason it is important to supervise rats when they are out of their enclosure and limit what they have access to.

Many health problems in rats and mice are related to nutrition and digestive issues, dental problems or obesity (including diabetes).

Contact your veterinarian if you notice the following symptoms:

  • Loose stools or constipation, excessive or irregular urination.
  • Irregular or excessive eating or drinking.
  • Obesity or weight-loss.
  • Bald patches in the fur, redness or scabs on the skin.
  • Sores on the feet.
  • Lumps anywhere on the body.
  • Difficulty breathing or loud breathing noises.
  • Lethargy, depression or irritability.
  • Dull expression, eyes half closed or appear sunken.
  • Hunched position or difficulty moving.

– Lyane Scarlett B.Sc., Dip. Teach., Dip. Lab. Tech., V.N.


  • Meredith, Anna and Redrobe, Sharon. BSAVA Manual of Exotic Pets. 4th Edition. 2002. British Small Animal Veterinary Association, Great Britain.
  • Taylor, David. Small Pet Handbook. 2002. Harper Collins Limited, London, Great Britain.
  • Vanderlip, Sharon. L. Mice. A Complete Pet Owner’s Manual. 2001. Barron’s Educational Series Inc, New York, U.S.A.


Rats & Mice