Why Does My Cat’s Poop Smell So Bad?

Last Updated on June 29, 2021 by Julia Wilson

At a glance

It is normal for feces to smell unpleasant; if it smells overwhelming, there may be an underlying reason why.


  • Poor quality cat food
  • Sudden change in diet
  • Food intolerance (such as lactose intolerance)
  • Malabsorption disorders (parasites, infection, bacterial overgrowth, exocrine pancreatic insufficiency, short bowel syndrome, pancreatitis, IBD)


This will depend on the underlying cause.


Let’s face it, no poop smells nice, but if the smell is so strong that you can smell it in the next room, or if the smell is worse than normal, there may be an underlying cause.

What is a normal cat stool like?

Keeping an eye on your cat’s stools is important as they can sometimes reveal an underlying health condition.

  • Cats usually defecate (pass a stool) between one to two times a day
  • The stool should be well-formed, and soft, not watery or in dry and/or in pellets
  • The normal colour for a stool is chocolate brown
  • There will be an odour to the stool, but it should not be overpowering, if you can smell it more than 1-2 feet away, it’s on the more smelly side

Causes of smelly feces

Low-quality food

All commercial dry cat food contains some form of carbohydrate fillers which are necessary for the pellets to hold their shape. Cheap brands of cat food can contain higher levels of low-quality fillers to produce cost-effective food.

Fillers (such as corn and other grain fillers) are not a part of the cat’s natural diet and are poorly digested, which can often lead to GI upset, along with flatulence and smelly feces. Corn is

It is also worth noting that cheap products don’t necessarily save money because they are lower in nutritional value than premium brands; the cat needs to consume more to meet its dietary needs.

By law, cat food packaging must label its ingredients in order of the highest level to the lowest level, so always look for brands which list meat/s (such as chicken, beef, lamb) in first, and preferably second and third too.

Some cats do just fine on cheap cat food; in my experience, cheap brands did cause their feces to take on a much stronger smell. They have since been switched to a mid-range brand (along with raw chicken wings), and there is a noticeable improvement in their feces.

All pet foods (even cheap brands) which have the words ‘complete and balanced‘ on their packaging must meet AAFCO standards.

A sudden change in diet

Some cats can be sensitive to changes in diet which can lead to mild stomach upset. Even if you haven’t changed brands, the pet food manufacturer may have changed an ingredient that can cause an upset.

If you do want to swap the type or brand of food you feed your cat, do so gradually, over several days by adding a small amount of the new food to the current food, increasing the new food while decreasing the old food.

Food intolerance

Food intolerance is an adverse reaction to food, one of its ingredients or additives. It differs from a food allergy in that there is no immune system involvement. Food allergies typically cause nonseasonal itching, especially around the head and face, swollen and inflamed areas on the face and ears, hair loss due to itching, vomiting, strong-smelling feces, and diarrhea.

A common food intolerance that many people have heard of is milk. This is because mammals stop the production of lactase, the enzyme necessary to digest lactose, which is the major sugar in milk.

Other causes of food allergies and intolerances in cats are fish, beef, eggs, wheat, and milk. Cats can become allergic and intolerant to foods they have eaten for a long period.

Malabsorption disorders

Malabsorption syndrome is several disorders in which the small intestine can’t absorb enough of single or multiple nutrients. There are many steps involved in the process of digestion, and any defect can cause malabsorption.

What should you do?

It is always recommended that changes to your cat’s litter box habits be checked out by a veterinarian. Bring along a stool sample which may provide a pointer as to the underlying cause.


The veterinarian will obtain a medical history from you, which may include:

  • How long have the feces been smelly?
  • What is their consistency?
  • What do they look like? Dry, pale, frothy, greasy, bloody?
  • What is the cat eating and drinking?
  • Is the cat on any medications or supplements?
  • Do you treat the cat for parasites?
  • Are there any accompanying signs?
  • Do the symptoms come and go?

Diagnostic workup:

Baseline tests: Complete blood count, biochemical profile and urinalysis to evaluate the overall health of the cat

Fecal flotation: A small sample of stool is mixed in a tube with a liquid flotation solution, the solution is strained to remove solids and centrifuged for five minutes. A coverslip is placed over the tube and left for ten minutes. The coverslip is removed and placed liquid side down on a microscope slide and evaluated for worm eggs.

Fecal smear: A thin smear of feces is examined under a microscope to identify Giardia trophozoites.

Snap test: IDEXX Laboratories have a SNAP Giardia test kit which is available for in-house testing, the sensitivity of this test is 90%.

Diagnostic imaging: Xray or ultrasound to evaluate the organs, look for cancer.


This will depend on the underlying cause but may include:

  • Gradually change the cat over to a high-quality diet.
  • Avoid milk or other food products which may be the cause of food intolerances.
  • Regularly treat your cat for intestinal worms.
  • For cats with pancreatitis, address the underlying cause as well as supportive care including pain relief, anti-nausea medication, fluids as well as nutritional support.
  • Lifelong administration of pancreatic enzyme extract, high protein low fibre diet and vitamin B12 for cats with pancreatic enzyme insufficiency.
  • Dietary modifications, corticosteroids or other drugs to suppress the immune system and in some cases, antibiotics to treat inflammatory bowel disease.