Cat constipation and what to do about it

Cat constipation is a surprisingly common condition, but it can be very serious. Understand the causes and discover the most successful treatments.

cat constipation causes and treatments

Cat constipation is a surprisingly common affliction. It occurs mostly in older cats, but can also occur in kittens as well. Cat constipation is often easily treatable, but it can also be a medical emergency. If your cat has not done a poo at all for 24-48 hours (or longer than is usual for him), or if she is straining in the litter tray and not managing to produce anything, then please take her to a vet immediately.

Symptoms include: straining in the litter tray, producing small, hard feces, or no feces at all, vomiting or reaching, refusing to eat or drink water, dehydration, lethargy, a reduction in grooming and a rough, unkempt coat. The best indicator comes from monitoring your cat's litter tray habits. 

There are three parts to this article: firstly, we will consider the common causes of constipation and their implications; secondly we will discuss methods to resolve an episode of cat constipation; finally we look at long term approaches to prevent cat constipation in animals who are prone to it.

Part One: causes of cat constipation

Feline Dystaunomia

Feline Dystaunomia is a rare condition. The autonomic nervous system of the cat does not function properly. This means that the bowel is not able to move the feces along, which causes the feces to dry out and become impacted, or stuck in the bowel. Heart rate, respiration, salivation, perspiration, pupil dilation, blood pressure and glandular activity are all also affected. This would usually be obvious in a young kitten. If you think your kitten has this, take him immediately to your vet. Thankfully, this is not a common condition.

Blocked bowel: ingestion

A complete absence of poo for 24-48 hours can be a sign of a blocked bowel. A bowel can become blocked if your cat eats something she shouldn’t: a rubber band, tin foil, twigs, toys etc.

Blocked bowl: impacted Feces

A blocked bowel can also be caused by constipation. Cat constipation may start as a mild case of constipation, but if it is left untreated, it can cause a blocked bowel. This happens because the constipation causes the feces to remain in the bowel longer than it should. The longer the feces is in the bowel the more fluid is absorbed from the feces, because the bowel absorbs fluids as part of the normal digestive process.  Eventually, the feces can become so dry that it gets too hard to continue being passed through the bowel. This is called ‘impaction’ or ‘impacted feces’ and it requires removal by a vet, often via surgery.

Cat constipation: megacolon

Untreated constipation can also cause a condition called megacolon. Megacolon occurs when the bowel becomes stretched so much that it is no longer able to function properly and loses its ability to move feces along the bowel. When a cat is very constipated, the feces becomes larger, drier and harder than it should be. This can stretch the bowel beyond its normal shape. If this happens very severely, or moderately and repetitively, it can stretch the bowel permanently out of shape. This then affects the motility of the bowel, which means that the bowel cannot move the fecal matter through it effectively.  

Once megacolon is established, it is a condition that is hard to treat in cats, and cannot be reversed or corrected. Cats with megacolon are put on laxatives for life - usually Miralax or Lactulose, or a combination of both. The laxatives allow the feces to move through the bowel despite the lack of motility.


A dehydrated cat can suffer from constipation. The lack of water in the cat’s body means that the feces becomes dry and cannot easily be passed through the bowel. If this continues, ir can cause impaction. Dehydration can be very serious if not corrected quickly. If your cat’s dehydration is mild, you can give them feline rehydration salts (not human ones!), like Royal Canin Rehydration. If it does not improve, or if your cat’s dehydration is severe, take her immediately to your vet. Your vet can put your cat on a drip, which is the fastest way to rehydrate her.

Part Two: solutions for cat constipation

Things you can do at home

If your cat is managing to pass feces, but the feces are smaller and harder than usual, or he is straining more than usual, then you have 24-48 hours to attempt to help your cat at home. If he is not passing any feces, straining a lot, in pain or distress...take him to a vet immediately.

Laxatives: Lactulose

cat constipation treatment lactulose

Lactulose is a laxative that is used in humans. It is not licensed for use in cats, but is often prescribed by vets and seems to work well. Lactulose is an indigestible sugar, so it passes straight through the bowel. Lactulose can be purchased over the counter, without a prescription, in pharmacies. The suggested dose for a cat is 0.5ml-1ml, 2-4 times per day, but ask your vet for dosage amounts. It usually takes 24-48 hours to work. If your cat responds to the lactulose, it is very important to wean your cat off the lactulose slowly. Reduce the amount of lactulose, rather than the frequency. So if you were giving 1 ml, 4 times a day, reduce that to 0.8 ml, four times a day and then 0.6ml etc. Monitor your cats litter tray, and if he becomes more constipated take up the dose for a day and take him back to the vet.

Laxatives: Miralax

Miralax is another human laxative, also available in the UK without prescription. It draws fluid from the body into the bowl. It is important to make sure your cat is hydrated for this - if she is dehydrated, it could be dangerous to dehydrate her further. Follow your vet’s advice. Miralax is said by many to be a more gentle laxative than lactulose, but there are also reports that it may not be good for the nervous system. Do your own research on this and decide for yourself.

No doubt there are other laxatives available, please discuss this with your vet.


Please do not attempt to give your cat an enima unless you are a vet, or have significant experience of doing so! Enimas work by pushing fluid - usually water and some sort of lubricant, into the bowel. The added pressure and lubricant helps move the feces out. Enimas will help with feces in the large bowl, but not further up the system. Enimas should not be used where there is a complete blockage as it will simply add pressure without being able to help the situation.

Part Three: long-term prevention of cat constipation

Water, water...and more water!

All constipation is caused by a lack of water in the feces (apart from where your cat eats something she shouldn’t).  Therefore for any cat with a tendency to become constipated, sufficient water intake is essential.

  • Switch to a wet food with a very high moisture content. Try Bozita in jelly, or anything in jelly that has lots of water in it. Read our wet cat food reviews for more info

  • Do not give your cat dry food

  • Please remember when switching food to do it as gradually as you can. With a moderate case of constipation you may want to switch more quickly - if you do, make sure your cat is definitely eating the new food. If a cat’s calorie intake is significantly reduced, it can cause hepatic lipidosis - read more about hepatic lipidosis.

  • Get your cat a water fountain. They keep the water fresher and make drinking more fun. Leave a normal water dish down for your cat as well until you are certain he is drinking from the fountain.


If your cat regularly suffers from constipation, there are two main approaches to fibre that are commonly thought to help:

  1. Feed a high fibre diet: the theory is that fibre speeds up transit time through the bowel. Fibre is indigestible so it remains in the bowel and moves through it.

  2. Feed a low fibre diet: the theory here is that a low fibre diet results in the smallest volume within the bowels and therefore relieves pressure on the system

Yes...the two approaches appear to be exact opposites! But…..there is a slightly different take on the first option, which we will label 3:

  1. Feed very small amounts of fibre, only to encourage colonisation of the gut by beneficial bacteria. Think of it as feeding the bacteria in your cat’s gut, rather than feeding your cat. So add a tiny, tiny bit of pumpkin, scillium etc to your cat’s normal food each day - just enough for the bacteria to eat! Start small - with maybe ⅛ teaspoon twice a day and see if it helps. Some foods have small amounts of pumpkin and other vegetables in them, like Feringa kitten menu.

Option 3 seems to make the most sense, based on what we now know about the importance of bacteria within the body and specifically within the gut. Bacteria are an essential part of every living organism, humans included. Bacteria play an especially important role in the digestion and absorption of food within the gut.

Ultimately, if your cat suffers from frequent constipation, the approach to take will be a decision to be made by you and your vet. It will likely be a combination of several of the approaches described above.

Remember: cat constipation can be caused by a blockage, which is a medical emergency. Even if your cat’s constipation is mild, if it is left completely untreated it could cause a serious condition. So please take action sooner rather than later.

For a very detailed explanation of the feline digestive system please visit this website


- cat diarrhea: causes and treatment 

- wet cat food reviews 

- British Shorthair kitten availability