Why Is My Cat Constipated?

Causes of constipation in cats, how to tell it from a blocked bladder, and when to call your vet.

Quick Answer

Constipation means a cat has trouble passing poo, passes it rarely, or not at all, and it is uncomfortable and can become serious if left untreated.
A cat straining in the litter tray with no urine, or only tiny amounts, is an emergency because it may be a blocked bladder, so ring your vet immediately and do not wait.
If you cannot tell whether your cat is straining to poo or to wee, treat it as a possible urine blockage and ring your vet now.
Common causes include dehydration, megacolon, pain, a blockage or narrowing, litter-tray problems, stress and other illnesses.
Never give a cat a human enema, and use laxatives only on your vet's advice.

Finding your cat constipated can be worrying. If it goes on for a long time, poo can become severely impacted, which is very uncomfortable. Constipation is a relatively common problem in cats, especially as they get older or if they have another health problem.

Before anything else, check which kind of straining you are seeing. A cat that strains in the tray and passes no urine needs an emergency vet, not a wait-and-see approach. This guide explains how to tell the difference.

Tabby cat lying on a polished wooden floor – is your cat constipated? It can be easy to miss until you check the litter tray

What Can Make a Cat Constipated?

Constipation can affect any cat at any age. However, it is more common in middle-aged and older male cats, and obese cats are at greater risk.

Dehydration

When a cat is dehydrated, the colon reabsorbs more water, so poo becomes dry and hard. Vets Now lists dehydration as one of the most common causes. Not drinking enough is most common in cats that eat only dry food or do not have constant access to water.

Kidney disease is common in older cats and can lead to mild dehydration. Diabetes and certain drugs can also lead to dehydration.

Megacolon

Megacolon means a very enlarged colon that has lost its ability to contract and push poo along. Repeated bouts of constipation can lead to it, and it can develop over several months of severe constipation. In most cats the cause is unknown.

Pain

If it hurts a cat to pass poo or get into position, it may avoid going. Examples include a problem around the bottom, an injury, or arthritis in the legs, spine or hips. Abscesses and other painful skin conditions around the bottom can also make a cat reluctant.

Tabby and white cat lying on its side on a sunlit wooden floor – is your cat constipated or straining? Ask your vet

A blockage or narrowing

Something swallowed that will not pass, such as a bone, toy or hairball, can block the gut. So can a tumour, rectal prolapse, or matted fur around the anus. A narrowed pelvic canal, for example from a healed pelvic fracture, can also compress the colon.

Hairballs are one possible contributor only. Our guide Are Hairballs Normal in Cats? covers them in detail.

Litter tray problems and stress

Cats may hold on if the tray is dirty, another cat competes for it, they dislike the litter, the tray is in a noisy place, or they had a bad experience using it. Stress can also cause constipation, for example from household arguments, noise, not enough trays or a new pet. Cats that usually go outside may be put off by bad weather.

Signs Your Cat Is Constipated

Most cats poo between one and three times a day, and more often as kittens, but every cat is different. Contact your vet if your cat's pattern changes. Look for these signs:

Straining and difficulty passing poo, or digging around and spending extra time in the tray.
Trying several times in a row and repeatedly coming in and out of the tray.
Crying out or meowing while pooing, which indicates it is painful.
Passing poo less often, or small, very hard, dry poo, sometimes with blood or mucus.
A painful tummy: your cat may look hunched or growl when you touch it.
Lethargy, vomiting or eating less than usual.
Over-grooming the bottom, or redness or swelling around the anus.

A small amount of liquid poo can sometimes get past hard poo, so it can look like diarrhoea. Do not assume it is diarrhoea if your cat is also straining.

Straining to Poo or Straining to Wee?

It can be difficult to tell, especially in a female cat. International Cat Care stresses that this matters, because struggling to pass urine can be an emergency.

Check the litter tray for any urine, and look around the home for wee in the bath, sink, on cold hard floors or behind furniture.
PDSA says tail position can sometimes help: it is often held up when trying to poo and held down when trying to wee. Do not rely on this alone.
In a cat straining to wee, you may see small amounts of urine or blood around the vulva or penis, and the cat may lick that area.
A blocked cat may strain as if constipated, with frequent trips to the tray that produce little or no urine.

Blocked bladders happen almost exclusively in male cats, and female cats very rarely develop them. Even so, if you are not sure, ring your vet now. For more, see Why Is My Cat Straining to Urinate?

Emergency: Contact a Vet Immediately If…

Your cat is straining in the litter tray and producing no urine, or only tiny amounts.
You cannot tell whether your cat is straining to poo or to wee.
Your cat is crying out when trying to pee, licking around its back end, vomiting, hiding away, weak or very low in energy.
Your cat has a painful, tense tummy or has gone off its food while straining.

Ring your vet or the nearest emergency vet straight away. Do not wait to see if it improves, and never try to treat it at home. Without treatment a blocked bladder can cause kidney failure and can be fatal. A blocked male cat is not a condition to be left until the morning.

When to Contact Your Vet

Your cat is struggling to pass poo, seems uncomfortable, or cannot pass anything. Contact your vet for advice straight away.
Your cat has not passed poo when you would expect it to. Vets Now says a cat that has not passed poo for 48 hours needs to be checked by a vet. Do not wait for 48 hours to pass before calling: PDSA advises contacting your vet for advice straight away if you suspect your cat is having trouble pooing.
Your cat cries out when pooing, has blood in its poo or around its bottom, or growls when you touch its tummy.
Your cat is vomiting, eating less or lethargic as well as straining or not passing poo, as this may be a blockage. Blockages need to be treated as an emergency.

Do not wait to see if constipation sorts itself out. It is very uncomfortable and can become serious. If in doubt, ring your vet.

What to Do, and Not Do, If You Find Your Cat Constipated

Do not give human over-the-counter enema products. Vets Now warns that some contain enough potassium to kill a cat.
Do not give laxatives yourself. They are available for cats but should only be used on your vet's advice.
Encourage drinking by placing water bowls in different rooms.
Ask your vet whether a wet food or high-moisture, high-fibre diet suits your cat. Wet food helps hydration.
Keep litter trays clean and away from noisy areas, with one per cat plus one extra, in different parts of the house.
Brush long-haired cats regularly to prevent matted fur around the bottom.

How Vets Investigate and Treat Constipation

Your vet will take a history and examine your cat. It may be possible to feel a build-up of poo through the tummy, and a rectal exam is sometimes needed, occasionally under sedation. Further tests may include blood and urine tests, X-rays or ultrasound.

Treatment depends on the cause, how severe it is and how long it has lasted. A dehydrated cat may need rehydrating before it can pass poo. Mild cases may be managed with a prescribed laxative, diet changes and advice on drinking and litter trays. Severe cases may need hospital care, a drip and removal of impacted poo under anaesthetic.

If medical treatment is not enough, surgery may be needed. It is major surgery, but the long-term results are generally very good.

How Pet Med Direct Can Help

Pet Med Direct is an online pet pharmacy. If your vet prescribes medicine for your cat, you can find out how pet prescriptions work and see our cat medication range.

We also stock cat food, including veterinary diets, and a non-prescription cat digestive support range. Please speak to your vet before changing your cat's diet or starting anything new.

Some pet medicines require a valid veterinary prescription. Pet Med Direct can only supply prescription medicines after the prescription has been checked. Always follow your vet's advice and the directions on the medicine label.

Frequently Asked Questions

How often should a cat poo?

PDSA says most cats poo between one and three times a day, and kittens more often. Vets Now says around once a day. Every cat is different, so contact your vet if your cat's pooing habits change.

How long is too long for a cat to go without pooing?

Do not wait for a set number of hours or days. PDSA advises contacting your vet straight away if you suspect your cat is having trouble pooing. Vets Now says 48 to 72 hours without a poo may mean constipation, and that a cat that has not passed poo for 48 hours needs to be checked by a vet. So contact your vet as soon as you notice straining or a change in your cat's pooing habits.

How can I tell if my cat is straining to poo or wee?

It is not always easy to tell. Check the tray for urine, and note that a tail held up often goes with pooing and a tail held down with weeing. This is only a rough guide. If you are unsure, or no urine is coming out, treat it as an emergency.

Can I give my cat a laxative or enema?

No, not on your own initiative. Vets Now warns that some human enema products contain enough potassium to kill a cat, and laxatives for cats should only be used on a vet's advice. Phone your vet instead.

Can diet help if my cat is constipated?

International Cat Care says wet food helps hydration, which matters for a cat constipated by dehydration. A high-moisture, high-fibre diet may also help cats pass regular, softer poo. Your vet can recommend the best diet for your cat. Encouraging drinking can also help.

My cat passed liquid poo. Could it still be constipated?

It might be. A constipated cat can pass a small amount of liquid poo that looks like diarrhoea. If your cat is also straining, speak to your vet before treating it as diarrhoea.

Related Cat Health Guides

Sources and Further Reading

This article was researched from the sources listed above. It is general information for cat owners and is not a substitute for advice from your own vet.

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This article is for informational purposes only and does not constitute veterinary advice.
If you are concerned about your cat’s health, please consult a qualified veterinarian.