Rat Urine Residue

Rat urine contains all sorts of ingredients, primarily urea and water. The unpleasant chemical smell emanating from urine buildup comes mainly from ammonia, formed as the urea breaks down.

Ammonia can cause irritation and even burns if it comes into prolonged contact with rat or human skin. For example, if you have elderly rats who cannot move easily or clean themselves properly, they may develop painful urine burns on their undersides. Inhaling the fumes can exacerbate respiratory problems in both the rats and their carer.

Rat urine also contains small amounts of other minerals such as calcium, which can form a chalky deposit in heavily soiled areas of the cage. These deposits are harmless in themselves, but are not easy to remove.

On the plus side, rat urine and droppings are rich in plant nutrients and perfectly safe for home composting. That sharp ammonia smell comes from a nitrogen-rich substance that will do wonders for your garden.

To reduce the problems associated with rat urine, start by purchasing a spacious cage that is easy to clean, preferably one with a plastic base and coated wire bars. The prettiest cage might not be at all easy to clean out, so when choosing a new rat cage, examine and manipulate assembled cages rather than just looking at the pictures on the boxes.

Lay down several inches of an absorbent, paper-based bedding/substrate. Remove particularly soiled patches every day using a small plastic shovel. (Rats often choose one spot as a toilet area and use it consistently.) If the urine can’t reach the bottom, it can’t form deposits. Clean the entire cage out at least once a week.

For even easier day-to-day maintenance, try toilet training your pets. You’ll need a clip-on plastic rat or ferret litter tray and a substrate of a different texture from your normal one. Alternatively, make your own toilet. A loose plastic tray probably won’t work too well—the rats will move it around—but you could attach the tray to a corner with twist ties after drilling a couple of holes in it.

Note where your rats habitually pee. The next time you clean the cage, retain a small amount of the dirtiest substrate. Put this in the litter tray along with some of the differentially textured material and clip the tray into the toilet corner. Change the litter in the tray every day, retaining a little of the soiled material each time until your rats are exclusively or mainly peeing in the tray—it doesn’t really matter where they leave their droppings, which tend to be pretty dry and odorless.

To remove urine deposits that have already built up, mix white vinegar and water in a spray bottle. One part vinegar to four parts water is usually strong enough. The vinegar helps neutralize the smell and dissolve the deposits. Spray the deposits and leave the mixture for about an hour. Wipe the litter tray or cage bottom clean and scrape away any remaining residue with an old butter knife before rinsing with plain water and drying.

Rat urine doesn’t usually form that much in the way of chalky deposits, not nearly as much as you’d get from, for example, a rabbit. If you notice a lot of this sort of residue or any other changes in your rats’ urine or their peeing habits, consult your vet.