Fancy Mouse

Fancy Mice

Mus musculus (domesticated form)

Health & Illness in Fancy Mice

An ill pet mouse can happen very rapidly and it is important to keep an eye on your mice. As prey animals, by the time you notice a problem it can often be quite serious as they hide their pain. Keep a mite spray handy for any excessive scratching you notice. Make sure you know what the normal behaviour is so you can identify anything out of character and try to handle your mice regularly so you will notice any problems in breathing or movement.

Signs of illness include:

  • Poor coat condition, posture
  • Sudden weight loss
  • Squeaky, laboured or otherwise noisy breathing.
  • Lethargic and cool to the touch
  • Lack of interest in food or water
  • Diarrhoea or constipation
  • Excessive scratching

If your pet mouse has lost weight then see this list of tempting foods for ill mice. A healthy pet mouse should weigh between 30-40g although this can vary.

An ill pet mouse will be cared for by its companions so do not separate them. It is always worth taking at least one friend with them on any vet trips and unless absolutely necessary keep them together once returned. A lonely mouse will find it harder to recover and may even die from depression. Below is a list of the more common illnesses in pet mice:


Barberism in fancy mice is caused when one mouse overgrooms another to the extent that it causes bare patches in their coat. This can also involve nibbling at whiskers or tail tips.


Diarrhoea in mice can be treated by sprinkling Arrowroot powder over their normal food. Arrowroot can be obtained from most herbal food shops or your local supermarket. It is also important to ensure your mice are kept well hydrated so check their water bottles and bowls. A common cause of diarrhoea in mice is too many green vegetables in their diet.


Lumps in female mice are sadly quite common and can be a variety of issues, such as an abscess (often caused by fighting), polyp, prolapse or a cancerous tumour. Lumps can be removed at a trustworthy vets however some research suggests that they have a very high possibility of recurrence as there is a chemical in the lumps that prevent others occurring.

Abscesses are generally softer than cancerous lumps and can be drained by your vet. A mouse with a lump may still have many months of life left, depending on its location and does not need to be put to sleep until it begins showing signs of pain or unhappiness.

Scratching/Skin problems

Excessive scratching or grooming can led to serious skin problems. This can be caused by Mites, and the affected mouse may display anything from mild scratching to severe, with patchy hair and skin ulcerations. Beaphar spot-on can be a good treatment, bearing in mind adjustment must be made for the weight of your mouse. More serious causes of mites may require your vet to perscribe something such as Ivermectin.

Another cause of habitual scratching could be boredom, see our section on enrichment and general care for ideas of how to keep your mice happy. You may also want to consider changing your substrate as some mice can have allergies to a specific type.

Teeth problems

Like any rodent, a mouse's teeth are constantly growing so you must provide material to help wear it down. Occasionally a mouse with a jawbone or teeth abnormality may need regular trips to a vet to trim their teeth.