Why Does Cat Urine Smell Like Ammonia?

Cat urine has a strong, distinct, unpleasant odor reminiscent of ammonia. This comes from undiluted urea in the urine. When a cat passes urine, the urea undergoes a series of chemical reactions. The most important of these is the release of ammonia.

Ammonia has a distinctive, pungent odor. Even the slightest whiff of ammonia is undesirable in the home. Unneutered male cats have particularly strong-smelling urine due to hormonal reasons. Other explanations for cat urine smelling strongly of ammonia are too much protein in the diet, urinary tract infections, dehydration, and kidney problems.

Cats do not find the smell of their urine unpleasant, so do not ignore the strong odor.

Persistent odors invite the cat to urinate in the same spot. This is especially unwelcome if it happens outside the litter box.

Why Does Cat Urine Smell So Bad?

The smell of cat urine is not one of the assets of a cat. Cat urine has an intense and pungent odor.

An older cat with a strong urine odor is especially troublesome because it often has difficulty reaching the litter box quickly.

We must look at evolution to understand why cat urine smells so strong. Domesticated cats descended from animals that lived in the desert.

Because water was rare in these dry areas, cats evolved to absorb water from their urine.

This means a cat’s kidneys absorb as much water as possible from urine. For this reason, cats rarely drink and usually urinate less than other animals.

Unfortunately, depriving the cat of this water means urine is not diluted. Therefore, the cat releases pure urine when using the litter box.

This urine is composed of the following components:

  • Urea (carbamide) and uric acid: waste proteins filtered by the kidneys.
  • Urobiline (urochrome): a pigment that gives urine its traditional yellow hue.
  • Sodium: This is also filtered by the kidneys.
  • Electrolytes: These typically provide water balance.
  • Creatinine: A chemical waste compound produced by physical activity.
  • Bacteria: Possibly including Toxoplasma gondii.
  • Pheromones: For communication with other cats.

Urea is the biggest culprit of all, especially if not removed.

Urea breaks down over time and releases an increasingly strong odor. This is often where the smell of ammonia is associated with cat urine.

Why Does My Cat’s Urine Smell More Intense Than Usual?

Many cat owners ask the question of why cat urine smells so strong. If you notice the smell for the first time at some point, something might be wrong.

If your cat’s pee smells more substantial than usual, there’s probably a reason.

In a moment, we’ll discuss the strong smell of ammonia, the most common complaint associated with cat urine.

But two other odors also deserve our attention.

Why Does Cat Urine Smell Sweet?

A sugary smell of cat urine is a warning symptom of feline diabetes or, in rarer cases, a kidney disease. If your cat is overweight, diabetes poses a real risk.

Cats at risk for diabetes should eat a high-protein, low-carbohydrate diet. However, this brings its own problems, most notably a strong odor of ammonia in the cat’s urine.

It is best to prevent and not allow things to develop in this direction in the first place. One step you might consider is feeding smaller portions more often.

Also, skip the treats and discuss any supplements with a veterinarian to avoid possible side effects.

Most importantly, try to keep your cat active. This is easier said than done when cats reach an older age. Most likely, all your cat will want to do is sleep and eat.

However, if you can encourage your cat to play, it will be beneficial in the long run.

Why does cat urine smell like fish?

A fishy stench is another distinct smell that can be attributed to cat urine. This one is just as unpleasant as it sounds.

Check your cat’s anal glands for discharge if you notice this smell.

These glands give off a strong, pungent odor. Cats use the glands and the pheromones they produce to communicate with other cats.

The anal glands allow the cats to leave a message through their feces. Usually, this is a warning of a territorial claim.

When these anal glands become swollen, they become inflamed. This is painful for the cat and leads to the fishy smell in the urine mentioned earlier.

This means that the anal glands need to be squeezed. You can do this yourself or ask a veterinarian.

Also, watch out for discharge in your cat’s urine. Sometimes, the fishy smell is related to bacteria in the urethra.

As mentioned earlier, all cat urine contains bacteria. Some are benign, and others are harmful. These bacteria need to be in balance.

When the unwanted bacteria outweigh the good ones, an infection becomes likely. This may be a true urinary tract infection or a mild illness that resolves itself within a few days.

Why Does Cat Urine Smell Like Ammonia?

A strong smell of ammonia is probably cat owners’ most common problem with cat urine.

Even in a litter box, cat urine smells strong. When urine is left to stand, the urea is broken down, and ammonia is released into the atmosphere.

The easiest way to do this is to clean the litter box several times daily. This will also motivate your cat to use the litter box, as cats do not like defecating in an unclean litter box.

If your cat urinates somewhere in the home, outside the litter box, the ammonia smell will encourage them to continue to urinate there.

It will become increasingly difficult to control and remove the ammonia odor.

You should also ensure the odor is not coming from your cat itself.

Older cats find it difficult to clean themselves, especially if they are overweight or arthritic. This means that urine can stick to the fur.

Help the cat groom itself with unscented wet wipes.

Of course, cleaning up after your cat is only half the battle. If your cat’s pee smells bad, there’s usually a reason.

Find out what is responsible for the strong odor. If possible, take steps to eliminate it.


The most common explanation for cat urine smelling strongly of ammonia is hormones.

Cats like the fact that their urine smells so pungent. It supports them in sending a message when marking their territory or announcing their presence.

In this context, the smell of ammonia in cat urine is related to sex and reproductive status.

When an unneutered female is ready to mate, she announces it through her urine. Unneutered males reciprocate this message in the same way through their urine.

Male cats are also usually more territorial than their female counterparts. Male cats prefer to mark their territory with urine. The smell is distinctive and unique to each cat.

When male cats are neutered, the hormones in the body are adjusted. This directly affects the urea in the urine which is measured in molar mass per liter (mmol/L).

Intact male cats typically have a urea level of 1,640 mmol/L. This value drops considerably after neutering to about 900 mmol/L.

This reduces the strength of the ammonia odor in the urine. It also reduces the male cat’s urge to mark his territory. Once neutered, male cats are usually calmer and easier to train.


We have already discussed that cats get moisture and fluids from their urine. This means that cats are sometimes reluctant to drink water.

A natural tendency to be fussy about drinking water can exacerbate this. Common reasons for a cat refusing water include:

  • A foul smell from the tap water.
  • The bowl is too narrow, causing painful whisker strain.
  • There is too much or too little water in the bowl.
  • The bowl is near the food dish or litter box, resulting in an unpleasant odor.
  • Another cat has been drinking from the same water bowl.

Some cats are also naturally suspicious of still water. This, like the tendency to avoid water, is an instinctive behavior.

Cats always drink from flowing sources such as rivers or streams in the wild.

Dehydration produces a strong ammonia odor because too little fluid is circulating in the body.

In this case, the kidneys retain what little water they can find. This leads to an increasing concentration of urine and the associated ammonia odor.

You can test if your cat is dehydrated by gently pinching the back of its neck. If the skin snaps back, the cat is healthy.

If the skin is slow to regain shape, it lacks elasticity due to fluid loss. Then, encourage the cat to drink water.

Inappropriate Diet

An inferior or inappropriate diet may explain why your cat’s urine smells so strong.

As obligate carnivores, cats rely on a diet rich in protein. Unfortunately, however, you can have too much of a good thing.

When a cat consumes protein, the liver converts it into amino acids.

These acids can upset the pH balance in the cat’s body. The pH should typically be between 6.0 and 6.4.

If a cat overeats protein, the liver can no longer break it down. Older cats with equally aged livers will struggle with this more than most young cats.

The acidity in the urine leads to increased urea levels and a strong ammonia odor.

Fortunately, this is easily remedied without a significant change in diet.

Most reputable food brands offer a range of foods specifically designed for older cats. The ingredients in these foods take into account the performance of the liver in their composition.

If problems persist, you may need to rethink your cat’s diet.

Feed smaller portions more often and eliminate extra protein snacks with chicken or other meat pieces. Including more fish in the cat’s diet will also promote protein intake.

Urinary Tract Infections

Urinary tract infections are common in older cats, especially spayed females or cats with diabetes.

A bacteria imbalance in the bladder usually causes a urinary tract infection in cats. This imbalance could result from feces from a dirty litter box entering the urethra.

However, it could also be that your cat is struggling with bladder stones — these form when the minerals in the cat’s urine cannot be processed.

Once they harden into crystals, they grow larger and become stones. They block the urine flow, resulting in less dilution of the urine.

A cat living with a urinary tract infection often avoids the litter box. In the cat’s mind, the litter box causes the pain, not the infection.

The resulting urinating outside the litter box, leading to an increasingly strong odor, can quickly become a problem.

Some cats independently overcome a urinary tract infection, primarily if it occurs regularly. However, leaving your cat alone with the problem is not advisable.

A urinary tract infection is painful for your cat, so you should take him to the vet to fight the infection.

Kidney Problems

We’ve mentioned the effects of kidneys on feline urination several times before.

The point is that your cat may be living with significant kidney problems. Kidney failure becomes more common as cats age.

From the time a cat reaches adulthood, its kidneys begin to degenerate.

However, this is not as concerning as it may sound. Cats only need about 25% of their kidney function to live a full, normal life.

However, when the kidneys slip below this level of function, health problems begin to occur.

One of the most problematic elements of kidney hypofunction is acute uremia.

In this condition, waste is accumulated in the urea because the kidneys cannot process it adequately. This results in urine that smells strongly of ammonia and foul-smelling breath.

As your cat ages, it must be examined regularly by a veterinarian. Bring your cat in for a checkup at least once a year.

If your cat is unlucky enough to develop kidney failure, you may face a difficult decision. Kidney failure is one of the leading causes of death in older cats and eventually leads to death.

My Cat’s Feces Smells Like Ammonia

Sometimes, it’s not the smell of urine that worries cat owners but that of feces. Foul-smelling feces can be just as problematic – and arguably more unpleasant – than urine.

Before worrying about the smell of cat feces, ensure the odor is not from the urine.

Cats rarely pee in a dirty litter box, but sometimes they make an exception. Fecal matter can mix with stale urine and create a particularly unpleasant odor.

As with urine, there are several possible explanations for the ammonia smell in cat feces. The most common reasons include:

  • Inferior food that contains too few nutrients or too much starch, protein, or fat.
  • Allergies to a new food, such as grains or specific vitamins.
  • Bacteria in the gut, possibly caused by hunting mice or eating raw meat and fish.
  • Side effects of medications that cause hormonal imbalance.
  • An infestation of parasites in the intestines, with nematodes being the most likely culprit.

Try to change your cat’s diet and ensure the litter box is cleaned regularly.

If this does not lead to success, it is advisable to seek veterinary advice. A particularly foul-smelling stool may be an indication of health problems in cats.

What Can I Give My Cat Against Strong-Smelling Urine?

The proper remedy for strong-smelling urine depends on the cause of the odor. Consider the following measures:

  • Neutering male cats
  • Increasing fluid intake
  • Feeding a balanced and high-quality diet

If these measures are not successful, you should consult a veterinarian. Your cat’s kidneys and any warning signs of a urinary tract infection should be examined.

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I, Daniel Popovic (Place of residence: Germany), process personal data to operate this website only to the extent technically necessary. All details in my privacy policy.
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I, Daniel Popovic (Place of residence: Germany), process personal data to operate this website only to the extent technically necessary. All details in my privacy policy.