Nerves can also cause diarrhea in the short term, but this should only occur when the mouse is being handled/upset. On other occasions it will be caused by bacteria (ie food poisoning) or other infection, eg coccidiosis. If your mice are affected, keep them warm and make sure plenty of fresh water is available.
Take your vet’s advice on perhaps adding a re-hydration solution to the water. Cut all green stuff out of the diet for the moment. Many mouse breeders swear by Arrowroot as a traditional remedy for diarrhea; you can feed the mice arrowroot biscuits (sold for humans) or arrowroot powder mixed in water.
Arrowroot is a cooking ingredient that you should be able to find at your supermarket or grocery store. Ask the staff for help- it’s used for thickening sauces. Try a pharmacy if the store doesn’t have it. If cutting out green stuff and feeding arrowroot does not produce results within a day or so, and the mice appear unwell, then contact your veterinary surgeon as treatment will be needed. Probiotics can help to cure diarrhea, whatever the cause.
These are friendly bacteria which live in the gut and help good digestion. The best ones are found in powder form and added to the water, eg Entrodex – ask your vet if they sell a similar product.
A less good but easy to find alternative is live natural yogurt – offer the mouse a small bowl. It is important to encourage the mouse to drink, and to keep her hydrated – ask the pharmacist for some re-hydration solution for humans, eg Dioralyte, or add a tiny bit of sugar and salt to the water.