What’s the Deal with Cat Litter Odor and What Can You Do About It? (Part 1)

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Every cat parent feels the burn of embarrassment when wondering if their apartment or house has that 'OMG a cat lives here' odor. We spray room scents, we light candles, yet that thought still creeps in when guests arrive. We love our cats: their expressive eyes, their affectionate purrs, and their quirky head bumps. But nobody loves a dirty cat litter box, and, no, I won’t try to convince you to. In fact, I want to take a closer look at what causes cat litter odor and offer some solutions to this less-than-lovable problem.

What Makes Cat Litter So Smelly?

Let’s get one thing out in the open: Nobody expects bodily waste to smell good. While both cat urine and cat feces smell, most people associate the potent scent of cat urine as being uniquely unsavory. It’s undeniable that cat poo can also kick up a stink storm. When you add the two together, you get cat litter odor: a universe of unpleasant not-so-fresh smells. But what exactly makes them so pungent?

How Does Cat Urine Contribute to Cat Litter Odor?

Have you ever noticed that the longer your cat’s litter sits the more unpleasant the smell becomes? While you may assume the smell multiplies because your kitty has visited several times, this isn’t necessarily the case. This aspect of cat litter odor is actually caused by your cat’s natural diet. Cats require high protein diets. You’re probably well aware of this. What may surprise you, is this protein is the primary culprit when it comes to cat litter odor.

How does this work? As your cat’s body metabolizes its dinner, it converts food into energy or waste. Before protein can convert to your kitty’s strong muscles and healthy bones, it goes through an interesting journey. Protein is processed and split into material used to keep your cat healthy and strong. When these components reach your cat’s kidneys, they filter the protein further and sort out the waste. This process creates a byproduct called “urea” (sounds like “urine,” right?). Which is unusable, therefore, must make its exit.

Urea isn’t actually that smelly. In fact, it’s considered odorless for the most part. But as it sits and is exposed to air, it transforms into ammonia. So, the longer it sits, the more noxious it becomes!

In addition to the presence of urea, there are some other factors that make kitty pee uniquely odorous. Nature didn’t think cats needed to use the potty one million times per day, so their bodies naturally concentrate their urine. This came in handy when it came to marking territory, but is totally out of fashion in the cat world today.

Why Do Some Cats Have Extra Stinky Urine?

Cats get a bad reputation when it comes to their number-ones, especially male cats. Is this fair? Well, we can definitively say that male cat urine CAN smell worse. Male cats, particularly those that haven’t been fixed, have high levels of hormones and testosterone. These hormones in addition to the undiluted nature of kitty urine can be extremely pungent.

Why Does Cat Feces Smell Bad?

Have you ever been relaxing, watching Netflix, and the smell of your cat's number-two, uninvitedly, invites itself to the party. There’s no ignoring it. But if you’re anything like me, a tiny voice asks, “is it possible that some animals’ poo might smell worse?” While it can be near impossible to find a scientific study that compares the odor of cat poop to that of dog poop (or whatever comparison you may think of), the general consensus is that cat poo smells pretty bad. Why? Diet, bacteria, and age.

Your cat’s high protein diet strikes again! When your cat digests its breakfast, lunch, or dinner, nutritional component breakdown as they’re exposed to healthy gut bacteria. As food is digested, the rearranging of material causes gases to be released or formed in your cat’s tummy. Processing protein creates urea, as mentioned before, but also sulfur which smells like rotten eggs. And as your cat’s waste sits in its litter pan, natural bacteria multiplies and emanates a foul smell.

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The right choice, for your kitty and the earth.

Recent studies also suggest as cats age, the bacterial microcosm of their bellies changes and deteriorates. This can lead to higher chances of digestive problems and reduced intestinal function.

The truth is cat poop smells, and until researchers (like these) find a way to eliminate the sulfur produced by digestion, it will never smell pleasant.

How Does Your Cat Feel About Her Stinky Bathroom Business?

Cats are clean freaks. They groom and groom and groom some more. In fact, most cats spend about 50% of their active hours cleaning themselves (they probably dream about grooming, too). Their elevated hygiene standards help:

  • Keep them hidden from predators in the wild
  • Loosen and remove excess fur
  • Stimulate healthy blood flow
  • Bond with other cats
  • Alleviate stress

Needless to say, cats don’t like to stink. They don’t enjoy a smelly litter box as well. This can trigger insecurities and make them feel vulnerable (see reason one above). The stink of bacteria can also be a difference since bacteria can signal disease; the same reaction you have when smelling sewage or rotten food. Your brain screams, “Stay away!”

When your cat’s litter box doesn’t smell fresh, your cat may resort to going outside the box or in a new spot in your home.

When Should You Worry About Your Cat’s Litter Odor?

If there’s any positive about being aware of your cat’s litter odor, it’s that it can help keep you aware of your kitty’s urinary and digestive health.

Smelly or Abnormal Cat Urine Can Indicate:

  • Dehydration
  • A kidney problem
  • A bladder problem
  • An infection
  • An inflammation
  • Cysts
  • Tumors
  • Hormonal Disorder

Extra Stinky and Abnormal Bowel Movements Can Be a Symptom Of:

The Take-Away of Your Cat’s Litter Box Odor

Our cats are irreplaceable. We love them no matter how many times they knock our pens off our desks or cover our clean laundry with their fur. Part of living with our feline friends means acknowledging that they pee and poo, and that's ok. When it comes to spotting urinary or digestive issues, embrace your kitty’s waste. It’s a great indicator!

Did you think I was going to leave you with just an article on why your cat’s waste smells bad? Of course I have more to say on the topic, and lucky for you, it’s about how to reduce and eliminate cat litter odor in a healthy way! Now that you know more about the reasons why your cat's litter is smelly, do something about it! Read part 2 of this series and learn simple solutions to control your cat's litter box odor.

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Introducing TofuKitty litter

Hi, I’m Molly, an environmental ecologist and creator of TofuKitty. I created a new kind of litter that was made with you, your kitty, and the planet in mind. You shouldn’t have to choose between effective cat litter and making green choices. My litter is:


Triple odor protection


Dust free




Low tracking

Chemical free

Super absorbent

Pest free

Soft on paws

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The right choice, for your kitty and the earth.
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The right choice, for your kitty and the earth.

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