why does cat pee smell so bad
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Why Does Cat Pee Smell So Bad?

Est. read time: 8 min.

There’s perhaps no smell more distinctor distinctly nose-wrinklingthan that of cat urine. But why does cat pee smell so bad? And why does it smell so much worse than dog urine? Veterinarian Dr. Justine Lee weighs in on this pungent mystery in the video below.

What does cat pee smell like? 

The smell of cat urine is often described as a strong, musky odor or even a sulfurous scent. While these comparisons may vary from person to person, the general idea is that the scent is strong, distinctive, and not typically considered pleasant.

Why does cat pee smell awful?

cat in the desert - evolutionary reason why cat pee smells awful

So why does cat pee smell so bad? The real question is: what makes cat pee smell?

The unpleasant smell associated with cat urine is primarily due to the presence of ammonia, which is present in cat urine due to evolution. Cats originated from the desert and evolved to absorb a large amount of water from their urine to maintain their hydration. As a result, cats have very concentrated urine, much more than dogs in comparison, which is also why you rarely see them drink.

Ammonia has a strong and pungent odor, which can be particularly noticeable in concentrated amounts, such as in cat urine.

In her book "It’s a Cat’s World… You Just Live In It," Dr. Lee writes that a cat’s loop of Henle (the part of the kidney that results in filtration and concentration) is so good at squeezing out every last drop of absorbable water that this concentration makes the urine smell very foul.   

Factors that make cat urine smell worse

The smell of cat urine can be influenced by several factors related to the cat's diet, hydration level, and overall health:

  • Diet: The type of food a cat consumes can impact the odor of their urine. Foods high in protein, for example, can result in stronger-smelling urine.
  • Hydration level: If a cat is not adequately hydrated, their urine becomes more concentrated, leading to a stronger odor.
  • Absence of neutering/spaying: Male cats that have not been fixed have the added effect of testosterone, making their urine smell even more foul.
  • Health factors: Various health conditions can affect the composition and odor of a cat's urine. For example, urinary tract infections, diabetes, hyperthyroidism, or kidney problems can alter the chemical makeup of the urine and result in a more noticeable or unpleasant smell.
  • Bacterial breakdown: If cat urine is allowed to sit without proper cleaning, bacteria can begin to break down the components of the urine. This decomposition process releases additional compounds that contribute to the overall odor. Regular cleaning of the litter box helps prevent the buildup of bacteria and reduces the chances of an intensified smell.
  • Location: If the litter box sits around in the sun, is close to the heater or furnace, or is near a vent, it can aggravate the cat urine smell and further spread it around the house. 

Why does my cat's pee smell so strong all of a sudden?

why does my cats pee smell so strong all of a sudden - testing a cat's urine in a lab

If you notice a sudden change in the strength of your cat's urine smell, it might indicate changes in behavior or even some health issues. Here are some possible reasons why your cat's pee may suddenly smell stronger:

  • Dehydration
  • Changes in diet
  • Stress or anxiety
  • Environment changes such as a new litter type or location
  • Medication

A sudden and strong cat urine smell can also be a sign of medical issues such as:

  • Urinary tract infection
  • Diabetes
  • Kidney problems
  • Bladder issues
  • Thyroid dysfunction

If you notice a persistent change in urine odor, it's crucial to consult with a veterinarian for a thorough examination and appropriate diagnostic tests. A veterinarian can perform a thorough examination, conduct relevant tests, and help identify and address any underlying health issues or environmental factors contributing to the change in urine odor. 

Tips to reduce the cat pee smell

reduce the cat pee smell with a self-cleaning litter box

Getting hit with a whiff of cat pee smell anywhere other than the litter box is mildly terrifying because every cat parent knows how difficult it is to eviscerate this particular odor.

If your cat is urinating outside the litter box, there are a few ways to get to the root of the problem:

Clean the litter box more often—or invest in a self-cleaning litter box!

Cats are fastidious about a clean litter box, especially if they’re sharing with a feline sibling or two. Keep in mind that you should have one more litter box than the number of cats in the houseso if you own one cat, you should have two litter boxes and be scooping them once a day. If have multiple cats, the ideal number of litter boxes goes up from there. 

Another option is to invest in Litter-Robot, which features a patented self-cleaning cycle that ensures a clean bed of litter after every use. Litter-Robot sifts waste within minutes, and the carbon-filtered, tightly sealed waste drawer or optional OdorTrap Packs are designed to greatly reduce unpleasant odors. Plus, up to four cats can use one Litter-Robot!

Thoroughly clean the affected area 

Whether they’re old stains or new spots, it’s important to remove cat urine smells as soon as possible. 

The most effective way to get rid of cat pee smell is with enzyme cleaners (found in pet stores or online), which break down the acid in cat urine, helping to get rid of the smell at the same time. These cleaners contain natural enzymes and helpful bacteria to get rid of the bad bacteria causing the unpleasant odors. Make sure to liberally douse the affected area with enzyme cleaner (rather than lightly spraying it as the bottle might say) and let it sit for 10-15 minutes before blotting.

Some people have found that a mixture of household ingredients like vinegar, hydrogen peroxide, and baking soda are effective at removing a urine stain, but this trick may only temporarily neutralize cat pee smell. When in doubt, try both types of cleaners or contact your veterinarian for their recommendation!

Pay attention to changes in your cat's environment

Your cat may be peeing outside the litter box due to a sudden change in their environment. In other words, your cat may be expressing their anxiety through inappropriate urination, which by proxy, has a negative impact on you. Consider whether there are any new stressors in your cat's life, and how you can minimize their exposure to these possible factors. A little environmental engineering can go a long way. 

Neuter (and spay)

Male cats that have not been fixed have the added effect of testosterone, making their urine smell even more foul. Neuter your cat before five months of age to combat this extra stinkiness and to minimize behavioral problems like marking or spraying around the house.  

Take your cat to the vet

Urinating outside the litter box or if your cat suddenly stops using the litter box may also be a symptom of a medical issue. Take your cat in for a quick examination and a few routine tests so your vet can rule out a urinary tract infection, urinary crystals, kidney disease, and diabetes.

Is cat pee toxic?

Cat urine itself is not generally considered toxic to humans, but it can contain certain substances and bacteria that may pose health risks.

The primary concern is the presence of ammonia, which gives cat urine its characteristic odor. Inhaling high concentrations of ammonia can irritate the respiratory tract and may cause discomfort, especially for individuals with respiratory conditions, meaning cat urine can potentially make you sick.

Prolonged exposure to ammonia in cat urine or contact with soiled litter can potentially lead to health problems; So it's important to take precautions, especially for pregnant people and individuals with compromised immune systems.

Source: Dr. Justine Lee, DACVECC, DABT