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Why Does Cat Pee Smell So Bad? 4 Main Reasons

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By Nicole Cosgrove

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Dr. Paola Cuevas

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Anyone who has a cat knows just how bad that litter box can smell. Even the healthiest of cats can have a pungent odor. This is simply due to the chemicals within the urine. However, other factors can cause cat urine to smell worse, such as diet, age, and illness.

Here are four reasons that cat pee smells so bad, as well as what you can do about it.

What Is in Cat Pee?

Cat urine isn’t all too different from human urine. Urine is simply waste that your cat’s body is flushing out of its system. Urine contains urea, ammonia, uric acid, and creatinine. The urea gets broken down by bacteria, resulting in an ammonia-like smell. More than likely, this is what you are smelling when your cat pees.

The 4 Main Reasons Why Cat Pee Smell So Bad

1. Chemical Decomposition

  • Serious: No
  • Treatment: None

The number one reason why cat pee smells bad is because of ammonia. Whenever your cat pees, bacteria start decomposing the urea. This decomposition process releases chemicals that have an ammonia-like smell.

Unfortunately, this chemical decomposition is completely natural and uncontrollable. In other words, there is no way to prevent this chemical decomposition from smelling. It is just a natural part of the cat’s bathroom aftermath.

The only way to mitigate this smell is to clean the litter box routinely. Make sure that the cat only goes in the litter box too, or else these decomposition smells will permeate the rest of your home.

cat pee stain in couch
Image Credit: Creative Cat Studio, Shutterstock

2. Diet

  • Serious: Moderate
  • Treatment: Change diet

If your cat’s urine suddenly starts smelling worse, it is likely a sign that something is amiss. Your cat’s diet, for example, will affect how strongly the urine smells. The urine will start smelling very strongly if the cat does not have adequate hydration.

If you think your cat’s diet is to blame for the foul-smelling urine, talk to your veterinarian first. Your veterinarian will help to determine the actual cause of the odor and walk you through a game plan. In the case that diet is to blame, your vet will recommend new food and additional water.

3. Age

  • Serious: Moderate
  • Treatment: Increase water

As your cat starts aging, its kidneys and other organs won’t be as effective as they used to be. A consequence of this is that the cat’s urine will smell stronger than it ever did before. This is just an unfortunate part of the aging process.

Although there’s nothing you can do to slow the aging process, it’s important to keep a close eye on your cat. Their urine can be one of the first signs that something is truly amiss inside your cat’s body.

If the issue is getting notably worse, talk to your vet to make sure there are no underlying diseases. In the meantime, make sure your cat has constant access to water so that the different nutrients can be flushed out at least a little bit easier.

old calico cat
Image Credit: Kristi Blokhin, Shutterstock

4. Illness

  • Serious: Moderate to severe
  • Treatment: Talk to your vet

Incredibly pungent urine can be a sign of a serious illness. If your cat’s urine suddenly changes overnight, there is likely an illness or disease at play. Issues such as inflammation, urinary tract infection, tumors, and hormonal disorders can all increase the odor of the urine.

It’s imperative to take your cat to a vet if you suspect the illness is to blame for its urine odor. Your vet will do a thorough evaluation to determine the problem and propose a treatment plan to help fix the problem.

How Do You Stop Cat Urine from Smelling?

Unfortunately, there’s very little you can do to stop cat urine smell if there is no underlying problem. All healthy cats will have foul-smelling urine. The only thing you can do is diligently clean the litter box and make sure your cat has good hygienic practices.

Messes and smells are part of living with a cat, but you don't want to spend your whole day cleaning!

hepper bioenzymatic litter additive

Our Hepper Advanced Bio-Enzyme Cat Litter Deodorizer can help keep your litter box smelling fresh for longer. This natural litter additive uses bio-enzymes to "eat away" the odors, saving you time and money. It's fragrance-free, safe for cats of all ages, effective on all types of litter, and fully biodegradable.

That being said, make sure your cat has a healthy diet and constant access to water. An improper diet and lack of water will make the odor worse. If you suspect that there is an underlying problem at play, talk to your vet to be able to fix that problem. Once the problem is fixed, the urine should go back to its normal level of foulness.


Unfortunately, all cat pee smells bad to some degree. Even the healthiest of cats have foul-smelling urine. However, urine can smell worse because of diet, age, and underlying diseases.

Always make sure your cat has a healthy diet, constant access to water, and a clean litter box. These three factors will largely keep unmanageable urine smells at bay. If these three things are not working, talk to your vet to make sure there is no underlying issue plaguing your cat’s body.

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Featured Image Credit: Creative Cat Studio, Shutterstock

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