Ask A Vet: Why Does Cat Pee Smell So Bad?

| Published on February 1, 2017

You know the smell of cat urine. It lingers long after you clean the box and if your cat pees on something else, you know right away.

If you think about what urine is, you’ll realize that you can explain some of what you smell already. Urine is the byproduct of a body’s metabolism. It is literally made up of a body’s waste. When a cat’s body breaks down proteins, urea is produced. The urea is then excreted by the kidneys into the urine for removal from the body . Urea itself is odorless, but it converts to ammonia. We all know what ammonia smells like!


To make matters worse for our noses, cat urine is processed  by a cat’s kidneys (in normal situations), so that it is concentrated. This means that the odor causing foulness is not diluted out much at all and even a little bit of cat urine can make a pretty strong odor.

Because of our cats’ lifestyle, their urine sits around for a while until we can clean the litter box and odors can become more obvious as bacteria act upon the urine. If a cat has a urinary tract infection, the smell may be even worse. The presence of hormones, like testosterone, that can concentrate in the urine can also lend a distinctive scent. Cats in the wild use their urine to territory mark and it has to be pungent to do its job. Tom cats that are not neutered win the award for the stinkiest pee on the planet, if you ask me!

Carefully cleaning the litter box each day, with a total strip down and wash with mild soap weekly, can help minimize urine smell. If you notice an unusually foul odor, especially if it is coupled with other signs of trouble, like straining, frequent trips in and out of the box, and/or urinating outside the litter box, it is time to call your vet.  It is extremely important to know that if your male cat is truly straining and unable to pass urine at all, the situation is absolutely dire and he must be taken immediately to a veterinary hospital or animal ER.

Stinky pee is a minor drawback to all the fun and love we get from our cats. Even though you might have to hold your breath a little while you clean the litter box, your cat is worth it!

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