Your cat’s litter box habits may not be the most exciting part of pet care, but they’re one of the most revealing. 

Cats are masters at masking discomfort, so subtle changes in stool can offer critical insight into their health. From soft stools to unusual colours or textures, this vet-reviewed guide helps you understand what’s normal, what’s not, and what to do about it.

If your cat’s poo has started to look different and you’re trying to work out what it means, you’re in the right place.

As veterinarians, we always remind pet parents that the litter box is one of the best windows into your cat’s health. Here’s how we recommend checking your cat’s poo at home – so you can catch problems early and keep your cat feeling their best.

Consistency

Healthy cat poop is generally well-formed, firm, and sausage-like. Too hard can mean constipation or dehydration, while too soft or liquid stools (diarrhoea) can indicate digestive upset or stress.

Colour

A healthy cat poo should be light to medium brown. Black stool may signal bleeding in the stomach or upper intestines, red blood streaks can be linked to lower intestinal inflammation, and yellow or grey stool often points to liver or pancreas issues.

Smell

We know cat poop always has an odour, but a strong, rotten, or sour smell can be a sign of gut imbalances or infection.

Mucus & Hair

A small amount of mucus is normal, especially in cats with sensitive guts. Large amounts, though, can indicate inflammation. While some hair in your cat’s stool is normal, excessive hair can suggest hairball issues or even a gut blockage that needs to be checked.

Foreign Objects

Cats love to play with things like string and ribbon, but these can end up in their stool if swallowed! If you spot any foreign bits in their litter box, keep a close eye out for repeat incidents.

Compact, well-formed poo that’s mid-brown and easy to scoop is usually a good sign. This kind of stool suggests your cat is digesting their food efficiently and staying hydrated. You’re likely to see it once or twice daily in cats on consistent, high-quality diets.

Stick to your current feeding routine, maintain access to clean water, and monitor as usual.

If your cat’s stools are loose or unformed, it could be a sign of food sensitivity, stress, gut imbalance, or a recent antibiotic course. The texture might be mushy, and you may notice stronger odour or increased frequency.

What next? Trial a digestible, limited-ingredient diet. Adding a probiotic may support recovery by restoring beneficial gut flora.

Should I see my vet? Yes, if soft stools persist for more than 2–3 days, worsen in appearance, or begin occurring more frequently, make an appointment with your vet.

Runny, liquid-like stool can indicate more significant digestive upset. It may occur suddenly or alongside vomiting, and your cat may strain, avoid the tray, or pass mucus. 

Common triggers include parasites, dietary changes, or inflammation. You may also notice signs like crouching, hiding, or reluctance to eat.

What next? Offer small, bland meals made from vet-recommended foods such as plain boiled chicken, steamed white fish, or cooked turkey (all unseasoned and boneless). A spoonful of plain pumpkin can help regulate digestion, while a splash of low-sodium broth (free from garlic or onion) can encourage hydration. Keep meals small, and serve them cool or slightly warm to entice your cat back to the bowl.

Should I see my vet? Diarrhoea in cats that lasts beyond 24–48 hours, especially if your cat becomes lethargic, loses their appetite, or shows signs of dehydration, needs veterinary attention. Kittens and senior cats are particularly vulnerable to fluid loss.

A shiny or jelly-like film around the stool suggests inflammation of the large intestine. Cats with this symptom may strain or make more frequent, smaller trips to the tray.

What next? Use a fibre-rich, gut-supportive food and add a probiotic. If your cat hasn’t been dewormed recently, check with your vet.

Should I see my vet? Yes, if the mucus appears more than once, if it’s paired with blood, or if your cat avoids the tray altogether.

Crumbly, dry, or unusually small stools often indicate constipation in cats. You might see your cat vocalising in the tray, straining, or producing only a few hard pieces at a time. In some cases, they may not pass stool at all for a day or two. This absence of stool can also be a red flag, especially in older cats or those prone to dehydration.

What next?  Encourage moisture by feeding wet food or adding warm water to meals. Consider fibre enrichment like psyllium or pumpkin.

Should I see my vet? Yes. If your cat hasn’t passed stool in 48+ hours, or shows signs of bloating or abdominal discomfort, a vet visit is warranted. Untreated constipation can develop into more serious conditions like megacolon.

Small amounts of hair in your cat’s poo isn’t unusual, particularly during shedding season or after grooming. But when hair starts wrapping around or running through the stool frequently, it may be a sign your cat is overgrooming or not passing hairballs effectively. Long-haired breeds are especially prone.

What next? Regular brushing and grooming can reduce the amount of ingested hair. You may also want to try a vet-recommended hairball control diet or supplement to help move things along more smoothly.

Should I see my vet? If you’re seeing excessive hair in the stool, or if it’s paired with constipation, vomiting, or changes in appetite, book a check-up. In some cases, ingested hair can lead to blockages that require veterinary care.

Smooth, uniform brown stool is the typical sign of healthy digestion. These stools are easy to scoop and leave minimal trace in the litter.

Bright yellow or orange stools may reflect bile moving too quickly through the gut, or poor nutrient absorption in the small intestine. It might follow a sudden food change or reaction to medication.

What next? Try transitioning to a sensitive-stomach formula under vet supervision and eliminate unnecessary treats.

Should I see my vet? If the colour remains after 48 hours, or your cat seems unwell or has reduced appetite, arrange an appointment.

Green stool is rare in cats but can occur after eating plant material or due to disruptions in bile processing. It’s typically soft and may have a sharp odour.

What next? Double-check what your cat might have ingested and review their diet. Watch for signs of nausea or appetite changes.

Should I see my vet? Yes, especially if green stool continues beyond one or two litter box trips or is paired with vomiting.

Visible blood in cat stool, especially bright red streaks, usually indicates irritation or inflammation near the end of the digestive tract. It’s often seen with constipation or rectal trauma.

What next? Add moisture and gentle fibre sources to help ease passage. Monitor your cat’s litter box behaviour closely.

Should I see my vet? If blood appears more than once, worsens, or is paired with discomfort, consult your vet promptly.

Tarry, jet-black poo is a serious concern. It often means there’s digested blood from higher in the gastrointestinal tract. Other symptoms might include vomiting, lethargy, or pale gums.

What next? Seek emergency veterinary care. Your cat may need blood tests, imaging, or in-hospital treatment. This symptom should always be taken seriously.

Pale, dry, or chalky stools may point to a lack of bile or too much calcium, especially in raw-fed cats. They may be difficult to pass and appear infrequently.

What next? Rebalance their diet and ensure adequate hydration. Avoid bone-heavy meals unless specifically vet-guided.

Should I see my vet? If stools stay pale or your cat becomes constipated, your vet should evaluate bile or liver function.

Greasy, pale grey poo often signals that your cat’s digestive system isn’t breaking down fat properly. This may result from pancreatic insufficiency or other absorption disorders. You might notice greasy fur, weight loss, or decreased appetite.

What next? Shift to a veterinary low-fat formula and remove any high-fat treats from their diet.

Should I see my vet? Yes. These symptoms are often linked to chronic conditions that require diagnosis and dietary support.

Cats won’t always show discomfort in obvious ways, so subtle changes matter:

• Avoiding the litter box for stool
• Excessive grooming near the base of the tail
• Yowling, hunching, or tensing in the tray
• Repeated but unproductive attempts to defecate
• Sudden change in stool location (e.g. outside the tray)

Noticing a shift in behaviour, even without obvious stool changes, can be your first sign that something’s wrong.

In the clinic, stool is often one of the most useful diagnostic tools I have. It's consistent, easy to observe, and packed with clues. If your cat’s poo has changed in texture, colour, frequency or smell, don’t ignore it. With early intervention, most digestive issues can be resolved quickly and gently.

Pay attention, take photos, and trust your instincts. Your cat’s gut health speaks volumes, even when they don’t.

This article was written by Dr Jane Miller