The smell of cat poop comes down to what’s happening inside your cat’s gut, what you’re feeding them, and how you manage the litter box. You can meaningfully reduce the odor by adjusting all three. Some changes work within days, others take a couple of weeks, but the combination makes a noticeable difference.
Why Cat Poop Smells So Strong
Cats are obligate carnivores, so their diet is naturally high in protein. When protein reaches the lower intestine undigested, gut bacteria break it down through a process called proteolytic fermentation. This produces ammonia, indole, phenol, and branched-chain fatty acids, all of which contribute to that unmistakable stench. A study in The Journal of Nutrition found that cats eating a very high-protein diet (55% of calories from protein) had significantly higher fecal ammonia and more of the bacterial enzymes responsible for producing these odor compounds compared to cats on moderate-protein diets (28% to 35%). In short, the more undigested protein that reaches the colon, the worse the smell.
This doesn’t mean protein is bad for cats. They need it. But the balance between protein, fiber, and digestible carbohydrates determines how much fermentation happens in the hindgut, and that’s where you have room to make changes.
Adjust Your Cat’s Diet
The single biggest lever for stool odor is food. Extremely high-protein diets with limited fiber leave more amino acids available for gut bacteria to ferment, producing more of those pungent byproducts. The same study found that when fiber and moderate carbohydrate levels were present, bacterial activity shifted from breaking down amino acids (proteolytic) to fermenting carbohydrates (saccharolytic), which produces far less odor.
Practically, this means choosing a food that includes some digestible fiber alongside quality protein. Look for foods that list ingredients like beet pulp, pea fiber, or chicory root. These aren’t filler; they feed beneficial gut bacteria and shift fermentation away from the smelly kind. You don’t need to switch to a low-protein food, just avoid formulas that are extremely protein-heavy with almost no fiber.
Some cat foods also include yucca schidigera extract, a plant-based ingredient specifically added for odor control. Research in the pet food industry has found that a dose of about 125 mg per kilogram of dry food is generally effective at reducing stool and urine odor, though higher amounts may have more impact. You’ll find it listed in the ingredients of many commercial cat foods marketed for indoor cats or odor reduction.
When switching foods, transition gradually over 7 to 10 days by mixing increasing amounts of the new food with the old. Abrupt changes can cause digestive upset that temporarily makes the smell worse.
Support Your Cat’s Gut Health
A healthy gut microbiome produces less odor. When the bacterial balance tips toward harmful species, you get more gas, looser stools, and stronger smells. Probiotics can help restore that balance, and there’s a growing body of evidence behind specific strains for cats.
Enterococcus faecium SF68 is one of the most studied strains in cats. In trials involving over 200 cats with diarrhea, it reduced diarrhea episodes within two days and improved fecal consistency. Lactobacillus acidophilus has been shown to improve fecal quality in healthy adult cats while increasing beneficial bacteria and reducing harmful E. coli counts. Lactobacillus reuteri similarly improved stool quality in Persian cats and shifted the gut flora in a healthier direction.
You can find cat-specific probiotic supplements as powders or chews from most pet retailers. Look for products that list specific bacterial strains and colony-forming units (CFUs) on the label rather than vague “probiotic blend” claims. Some prescription and premium cat foods also include probiotics in the formula itself. Results typically show up within one to two weeks of consistent use.
Clean the Litter Box More Effectively
Even with dietary changes, litter box maintenance is half the battle. Stool sitting in the box gives bacteria time to keep breaking down organic matter, producing more ammonia and sulfur compounds as it sits. The standard recommendation is to scoop waste daily. Picking a consistent time, whether morning or before bed, makes it easier to stick with. After scooping, replace the removed litter with a comparable amount of fresh litter so the depth stays consistent.
Once a week, dump all the litter, wash the box with soap and water, dry it completely, and refill with fresh litter. Plastic litter boxes absorb odors over time because the surface develops microscopic scratches that trap bacteria. Replacing the box itself every 6 to 12 months helps if you notice a persistent smell even after cleaning.
The type of litter matters too. Clumping clay litters seal moisture and odor into tight clumps, making daily scooping more effective. Some litters include activated charcoal or baking soda for additional odor absorption. Avoid heavily scented litters, which tend to mask rather than eliminate odor and can deter cats from using the box, leading to other problems.
Use the Right Cleaning Products
Standard household cleaners often just cover up the smell. Enzymatic cleaners work differently: they contain protein molecules that act as catalysts, breaking down organic compounds like uric acid and fecal matter into simpler molecules. Bacteria in the cleaner then consume those smaller molecules, eliminating the odor source rather than masking it. This makes enzymatic cleaners especially useful for cleaning the litter box during weekly washes, wiping down the area around the box, and treating any accidents on floors or furniture.
Avoid ammonia-based cleaners for litter box areas. Cat urine contains urea that breaks down into ammonia, so ammonia-based products can actually reinforce the smell and may discourage your cat from using the box.
Rule Out a Health Problem
If your cat’s stool suddenly becomes dramatically more foul-smelling, especially alongside other changes, the cause may be medical rather than dietary. Gastrointestinal parasites like Giardia and coccidia can cause diarrhea (sometimes with mucus or blood), a dull coat, vomiting, and decreased appetite. Giardia infections in particular often produce soft, greasy, intensely smelly stool, though many infected cats show no obvious signs beyond the odor change. Kittens are especially vulnerable to coccidia, which can destroy the intestinal lining and cause mucousy diarrhea.
Food intolerances, inflammatory bowel disease, and pancreatic insufficiency can also cause malabsorption, meaning nutrients pass through undigested and feed odor-producing bacteria in the colon. If dietary and litter box changes don’t make a dent, or if you notice diarrhea lasting more than a day or two, blood in the stool, weight loss, or vomiting, a fecal test can quickly identify or rule out parasites and point toward the real cause.
Ventilation and Box Placement
Where you put the litter box affects how much you notice the smell. Enclosed spaces like closets trap odor and concentrate it. A spot with some air circulation helps dissipate smells before they build up. If you use a covered litter box, keep in mind that the lid traps odor inside, which is great for you but unpleasant for your cat and can lead to litter box avoidance. An open box in a ventilated room, scooped daily, typically produces less noticeable ambient odor than a covered box cleaned less frequently.
A small air purifier with an activated carbon filter near the litter box area can also help. Carbon filters absorb volatile organic compounds, the same molecules responsible for the smell, rather than just circulating the air.