Wondering why your cat's poo smells so bad? It never smells good, but did you know that you can actually tell things about a cat by the way its poop smells? The smell of a cat's poo can tell you a lot about their diet and whether there might be some digestive issues.

Learn what a healthy cat poop smell is along with common causes of smelly stools and when you might need to call a vet.

Is Cat Poop Supposed to Smell?

Cat poo naturally has a smell. This is true of most animals, and us humans are generally not particularly fond of it. Cats are obligate carnivores, so their digestive system processes meat-based protein and can create stronger-smelling waste than some other pets.

A mild, unpleasant smell is normal, especially immediately after your cat has used the litter tray. However, a smell that suddenly becomes much stronger may not be normal. The same goes for a foul, rotten, sour or metallic and unusually intense odour.

You may also want to look out for a smelly poo alongside diarrhoea, blood, mucus, vomiting, lethargy or weight loss as potential signs of ill health. Cat litter can help control odour in the home, but a sudden change in poo smell shouldn't be simply covered up.

Cat poop smell should only be treated as one part of the bigger picture. Colour, texture, frequency and behaviour also matter.

What Should Healthy Cat Poo Look and Smell Like?

When it is healthy, cat poo has certain characteristics that are common to all cats. It should be medium to dark brown in colour, firm but not rock hard, and formed into sausage- or log-shaped pieces. You should be able to scoop it without it falling apart, and it shouldn't look dry or chalky.

It will be mild to moderately smelly, but not so overpowering that it fills the entire room for a long time. Many cats poo around once or twice per day, but some healthy cats will go slightly more or less often depending on things like:

• Age
• Diet
• Hydration
• Activity level
• Health

The key is to know what is normal for your individual cat.

Consistency is important. If a poo is too hard, it could suggest constipation, dehydration or diet issues. If it is too soft or watery, it might suggest diarrhoea, food intolerance, parasites, infection or digestive upset.

As an owner, you should monitor smell, colour, shape, texture and frequency. If you notice your cat straining, or pooing outside of the litter tray, these could also indicate something isn't quite right.

Why Does My Cat's Poop Smell So Bad?

There are several main causes that might lead to a particularly foul smell from your cat's poo. The causes can be simple like a change in their food, or something more serious like parasites or digestive upset. Let's look at the potential causes in more detail.

Diet and Food Changes

By far the most common reason for bad cat poop smell is the diet. Sudden changes in cat food can upset the gut, while low-quality food with difficult-to-digest ingredients or inappropriate treats may affect the smell of the stool.

High-protein foods can naturally produce stronger-smelling stools. You might also notice issues like smelly poo, soft stools, wind or vomiting if a cat has a food intolerance or sensitivity. Bear in mind that cats who hunt or eat things outside may have a less controlled diet, and it might not be clear what is causing their smellier stool.

Here are a few tips to avoid upsetting a cat's stomach with their food:

• Introduce new food gradually over 7–10 days where possible
• Avoid giving your cat rich table scraps, milk, too many treats or foods that aren't designed for cats
• Speak to a vet before making major diet changes if the cat has known digestive issues or food intolerances

Digestive Upset, Parasites and Illness

Though it's important not to attempt a diagnosis without a vet, it helps to be aware that there are possible medical reasons for bad cat poo smell. There are quite a few potential medical causes of foul-smelling cat poo:

• Bacterial imbalance in the gut
• Intestinal parasites or worms
• Digestive disorders
• Inflammatory bowel problems
• Anal gland issues
• Infection
• Medication or supplements affecting digestion
• Blood in the stool

The smell of the faeces on its own is not enough to confirm illness, but that smell along with other changes or symptoms is more concerning. We recommend that you take your cat to the vet if you notice a bad cat poop smell alongside diarrhoea, blood/mucus, a black colour, vomiting, loss of appetite, weight loss, lethargy or straining.

What Different Cat Poo Smells Might Mean

Smelly cat poo is not a reliable indicator of a specific problem, but there are certain types of smell that might be telling you something. The following table breaks down types of smells and their possible meanings to help you assess how to respond.

Type of smell	Possible meaning	What to do
Mild but unpleasant	Often normal cat poo smell	Keep tray clean and monitor for changes
Very strong after a food change	Diet transition or digestive upset	Slow down the transition and monitor stool
Sour or rotten smell	Possible diarrhoea, gut imbalance or infection	Watch for loose stools, vomiting or lethargy
Metallic smell	Possible blood in the stool	Contact a vet, especially if stool is black, red or tarry
Strong smell with mucus	Possible gut irritation, parasites or inflammation	Speak to a vet if it continues
Bad smell with watery diarrhoea	Digestive upset, parasites, infection or food intolerance	Contact a vet if severe, recurring or paired with other symptoms

Please bear in mind that this table should not be used to diagnose a cat at home. It is merely a guide to help you decide when to monitor the situation and when to seek veterinary advice.

When Should You Worry About Smelly Cat Poo?

A bad-smelling cat poo on its own is not necessarily a cause for alarm. As mentioned, there could be many causes, particularly if the cat is otherwise well. However, we recommend that you contact your vet if the unusual smell is accompanied by:

• Blood in the stool
• Black, tarry poo
• Watery diarrhoea
• Repeated diarrhoea lasting more than 24–48 hours
• Vomiting
• Lethargy
• Refusing food
• Weight loss
• Straining to poo
• Signs of pain
• Pooing outside the litter tray when this is unusual
• Worms or visible parasites
• A foreign object, string or plastic in the poo

Kittens, senior cats and cats with known health conditions can become unwell faster and should be checked sooner. If a cat seems very unwell, weak, dehydrated or unable to pass faeces, you should contact your vet promptly to get them checked out.

How to Reduce Cat Poo Smell at Home

There is no replacement for veterinary care, and if a cat poo smell is persistent or comes with other symptoms, you should get them checked. With that being said, cat poop smell is a common problem in homes, and there are things you can do about it.

Diet and Digestion

Here are some tips around diet to help reduce the odour:

• Feed a complete, balanced cat food suitable for your cat's age and health
• Avoid sudden food changes
• Keep treats limited
• Provide constant access to fresh water

With veterinary guidance, things like probiotics, sensitive stomach diets or prescription diets may be helpful.

Litter Tray Hygiene

Naturally, there are best practices with the litter tray that can help with the issue of smelly cat poo:

• Scoop poo as soon as possible
• Fully clean the litter tray regularly (maybe once a week)
• Use a suitable number of trays — a common guideline is one litter tray per cat plus one extra
• Place litter trays in quiet, accessible areas
• Avoid heavily scented products if the cat dislikes them, as strong smells may discourage litter tray use

Litter Choice

If you have good-quality cat litter, it can help absorb odour and moisture. Here are a couple of suggestions:

• Clumping litter may make it easier to remove waste quickly
• Health-monitoring cat litter can help you spot changes in your cat's toilet habits

Litter Sense cat litter is designed to help you monitor changes in your cat's urine by changing colour when there is an abnormal pH level or blood in urine. The silica crystal design is also helpful for odour control and convenient for changing the litter.

What Your Cat's Poo Colour and Texture Can Tell You

Beyond smell, the main indicators of the health of a cat's poo are the colour and texture. Here are some common stool types and what they tell you about your cat:

• Brown and formed: This is usually healthy.
• Very hard or dry: Possible sign of constipation or dehydration.
• Soft or runny: You might have a case of diarrhoea, food intolerance, stress, parasites or infection.
• Black or tarry: You might be looking at possible digested blood, so vet advice is recommended.
• Red streaks: This might be fresh blood, so vet advice is important.
• Yellow, grey or pale: These are possible signs of digestive, liver, pancreas or bile-related issues, which require veterinary advice.
• Mucus-coated: This is a possible sign of bowel irritation or inflammation.

Occasional variation can happen, but repeated changes should not be ignored. It can be helpful to take a photo of a concerning poo before you bring your cat to the vet so that they can assess what they see.

Final Thoughts: Don't Just Mask Cat Poop Smell

In summary, cat poo is supposed to smell, and many owners find it something they have to sort out every day. But a sudden or foul smell can be an early sign that something has changed, along with differences in colour, consistency and other behaviours from your cat.

Keep your litter tray clean and use a good-quality cat litter. Feed your cat an appropriate diet and monitor any changes you notice in their eating and toileting habits. You only need to contact a vet when a bad smell appears alongside other symptoms.

A cleaner, fresher litter tray does more than just improve the smell of the home — it also makes it easier to notice if there is a change in your cat's health.

Frequently Asked Questions About Cat Poop Smell

Why does my cat's poop smell so bad all of a sudden?

Sudden changes are often linked to diet, food intolerance, parasites, infection, medication or digestive upset. Monitor and look for other symptoms.

Is smelly cat poo always a bad sign?

No, cat poo naturally smells. The only time there is a cause for concern is when the smell is stronger than usual, persistent, or paired with other symptoms like diarrhoea, blood, vomiting, weight loss or lethargy.

Can cat litter stop cat poo from smelling?

Litter can go some way towards helping to absorb and control odours, but it can't stop a poo from smelling.

How often should a cat poo?

Many cats poo once or twice a day, but normal frequency is not a one-size-fits-all thing. Watch out for major changes in frequency, especially with straining or diarrhoea — these should be monitored.

What does unhealthy cat poo look like?

Watery, black, red, grey, pale, mucus-covered, very hard, very soft or unusually foul-smelling poo could all suggest there might be a problem.