**SmartlyCat is supported by readers. If you click one of my links I may earn commissions. Thank you.**

Why Does Cat Pee Smell So Bad?

why does cat pee smell bad

Whether your cat pees once or 5 times per day, something that all cats have in common is that their pee does not smell very good.

No, of course, urine in general is not a pleasant odor. However, when it comes to cats, this is a whole different ballgame.

Simply put, cat pee can stink something fierce. Sure, through various methods this odor can be controlled, but the pee is always going to smell. So, why does cat pee smell so bad?

Urine Concentration

One of the main causes of why cat pee smells as bad as it does is due to the concentration and strength of the urine. Cats were originally desert and dry land creatures, long before they were domesticated. Due to this, the cat’s body is designed to absorb as much liquid as possible.

When it drinks, the majority of that liquid will be absorbed into the body, thus leaving only small amounts of very concentrated urine loaded with stinky compounds.

For a comparison, a dog’s body does not absorb nearly as much of the liquid it drinks. In other words, it pees out more of the liquid it drinks than a cat, thus leaving the urine a dog expels far less concentrated, and therefore much less smelly.


Besides being super concentrated, there is another big reason why cat urine smells so bad — ammonia. Ammonia is very volatile, and its odor is extremely strong, even in minute quantities. Ammonia has a scent kind of like a horrible mix between rotten fish and rotten eggs.

Urea is the primary compound in urine, and when urea decomposes and breaks down, it creates and releases ammonia. There are plenty of bacteria found in litterboxes, and these bacteria can get into the litterbox in a number of ways.

The more bacteria there are, the more and the faster they will break the urea down and create ammonia. Cat urine also contains far more urea than dog or human urine, which is why there is a lot of ammonia created when it decomposes.

Felinine and Sulfur

Another reason why cat pee usually smells quite offensively is due to a pheromone found in cat urine, a pheromone adequately named felinine. Felinine is a pheromone that cats will begin to create and expel in their urine when they reach about 3 months of age. Unneutered male and female cats which have not been spayed produce the most felinine.

Now, felinine itself does not actually smell, but when it starts to degrade, it creates sulfur compounds. You might recognize sulfur as smelling like rotten eggs. Exactly how felinine degrades is not actually known, but it does degrade, and it creates sulfur when it does.

cat spraying no more review

Controlling Cat Pee Odor

Let’s quickly go over some useful tips on how to control cat urine odor so your whole house doesn’t stink.

You can get antimicrobial litter which prevents bacteria from building up. The less bacteria there are, the less urea will be degraded, thus less ammonia is released. This kind of odor elimination tends to work best.

Some kitty litter products also come with scents built into them. This is not odor elimination, just odor masking, and no, it doesn’t work as well as odor elimination. It’s like spraying yourself with cologne without taking a shower first.

Frequently scooping out used litter and replacing it with new litter is one of the best control methods.


Cat pee smells, but there are things you can do about it, and it usually all comes down to the type of litter you are using.

Related Posts

why does a cat knead

Why Does a Cat Knead?

what to do if cat scratches you

What to do if a cat scratches you?

cat spraying no more review