Mouse Pees On Himself

Why is an older mouse suddenly urinating on himself?

As mice age kidney disease, liver disease and even brain disorders may cause increased urination. Alexas_Fotos

By Karen Rosenthal, DVM, MS


One of my mice, his name is Patches, has been urinating himself the past three days. My first thought was wet tail, but he has an appetite; he still drinks, but he just doesn’t move a lot. There are four levels to his cage, and he’s only wandering on the bottom two — the easiest ones to reach. His feces are still solid, but he’s covered in urine. The trail is all the way up to his neck because he’s piddling in his nest. Whenever I clean him, he does groom himself dry. Today I purchased Pedialyte and all of his favorite fruits and veggies. I’m friends with a veterinarian who is going to get me some Baytril, and I have a stash of dry tail on stock but I’m unwilling to use it. I don’t want to wipe out his good bacteria unless I know for certain what happened. Is it because he’s old, for a mouse bought at a pet store, or is it a case of wet tail? Have you ever run across anything like this before?


Sorry to hear about Patches, your mouse. What you describe are signs of a nonspecific illness in a mouse. The term “nonspecific illness” means that many diseases cause this sign, and the actions of your mouse do not identify what type of disease may be present in your pet.

When small rodents and rabbits are sick, one of the first things they may do is decrease their activity level. As they become sicker, they stop moving altogether and may sit in a corner of the cage for hours. Possibly, they are conserving what energy they have left or maybe it is too painful to move.

When our pets start acting like this, they cannot or will not move to the usual area of the cage to urinate and defecate. Because they stay in one spot for hours at a time, each time they urinate, they sit in their urine. Over the course of a day, their feet and fur become urine-soaked. That may be what you are describing.

Also, in Patches’ case, it may be that not only is he sick and reluctant to move much, but it is possible he is drinking more than his normal amount of water due to metabolic disease. You said he is older. The combination of excess water intake due to disease and the reluctance to move can cause your mouse to be “soaked” in urine.

Increased urination can happen due to kidney disease, liver disease or even brain disorders. These conditions are not uncommon in older mice.

If this is an infection, an antibiotic may be an effective treatment but until a veterinarian is able to examine your mouse, it is impossible to guess what is causing this problem.

If you do go to the veterinarian, besides the physical examination, your vet will examine the urine for signs of infection and other disease. Blood tests may also reveal the health of the kidneys and the liver. Treatments exist for both conditions in mice, so I encourage you to bring your little guy in for an examination.

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Critters · Mice and Rats