Cat constipation: A vet's guide to the causes and symptoms

Maine Coon cat in litter box
(Image credit: Getty Images)

Unfortunately, cat constipation is pretty common. There are many possible causes, ranging from lifestyle factors to medical conditions. Constipation can be surprisingly hard to spot in cats since the symptoms can easily be confused with other issues. 

Considering how important early treatment and management are, it is key that you know what to look out for. Without early treatment, constipation can lead to other problems and is more likely to recur. So, let’s take a look at everything you should know about constipation in cats.

What is cat constipation? 

Constipation means difficulty passing poo (faeces or stools), passing poo infrequently, or not passing poo at all. 

In constipation, the faeces are held in the large intestine (the colon and rectum), where they builds up. Since one of the major functions of the colon is to absorb water from the stools, and it continues to do so while the stool is held in the colon, the stools get drier and harder with time. This makes it even harder for them to pass. 

When constipation becomes a chronic (long-term) problem, meaning the colon is being stretched over a period of time, this can lead to a condition called ‘megacolon’. With megacolon, the colon is stretched too large, making it unable to effectively push the faeces out. 

Causes of cat constipation

There are lots of possible causes for constipation in cats, ranging from factors in the environment to serious medical conditions. Possible causes include:

1. Environmental factors 

Cats are fussy creatures, so if they are used to pooing outside and need to be kept in, they may refuse to use a litter tray. Similarly, cats may take a dislike to a certain type of litter or tray, causing them to hold their stool while they wait for an alternative. A dirty tray or having to share a litter tray can also be off-putting to our feline friends. Since water is continually drawn from the stool by the colon, the longer they wait, the drier and harder the stool becomes.

2. Dehydration

When a cat is dehydrated, the body tries to conserve (keep) as much water as possible. This means it draws (re-absorbs) as much water from the stools as possible, making them hard and dry. This means constipation is common in medical conditions such as Chronic Kidney Disease (CKD).

3. A blocked colon

A blockage in the colon caused by a foreign body (i.e. the cat has eaten something it shouldn’t have), a polyp or a mass can cause constipation, by physically blocking the stool from passing. A build-up of hairballs can have the same effect! A colon can also become blocked if the pelvic canal (the internal area between the hip bones) becomes narrowed for any reason, such as following a trauma like a road traffic accident.

4. Pain

Anything that makes it painful to go to the toilet can cause a cat to become constipated. They realise that passing a stool will hurt, so are reluctant to go. Arthritis can make posturing to poo painful, for example.

5. Neurological conditions (involving the nerves)

If the nerves controlling the passing of faeces are damaged, for example in a ‘tail pull’ injury or after a road traffic accident, this can cause constipation (or on the flip side it can also cause incontinence). 

6. Idiopathic megacolon

Megacolon isn’t always caused by chronic constipation and sometimes occurs as a condition with an unknown cause. The wall of the distended colon is weak and unable to push faeces out.

Now that we know what might cause cat constipation, let’s take a look at how to tell if your cat is constipated.

Cat constipation symptoms 

A kitten sitting in a litter tray

(Image credit: Getty)

The symptoms will vary, and can mimic other problems, such as straining to wee. The main symptoms of constipation are:

  • Straining to poo, often with signs of pain
  • Passing stools less often
  • Multiple trips to toilet outside, or to the litter tray, without passing anything
  • Small, dry nuggets of poo
  • Small amounts of liquid stool (which are easy to confuse with diarrhoea, but are actually liquid stool managing to pass around the build-up of faeces).

You may also notice:

  • Lethargy (lack of energy)
  • Decrease appetite
  • Feeling or being sick

Is cat constipation an emergency? 

This depends a little on the cause. Cats normally poo every day, so at least once every 24 hours. if you’re wondering “how long can a cat go without pooping?”, the answer is that you shouldn’t leave them for more than 48 hours. If your cat hasn’t passed stools in the past two days (or more), then it’s time for an urgent trip to your vet!

If your cat is making frequent trips to the litter tray but not passing anything, it’s really important to be sure they aren’t actually trying to wee. If you aren’t sure if your cat is weeing, then you should call your vet straight away. Straining to pass urine, without actually passing any, can be a sign of a blocked bladder, which is a life-threatening emergency.

How is cat constipation treated? 

The treatment will partly depend on the severity and the cause. In severe or chronic cases, a constipated cat will need to have fluid therapy and manual removal of the faeces under a general anaesthetic. For less severe cases there are several medical options, including:

  • Enemas 
  • Laxatives
  • Prokinetics (which stimulates the colon to contract, to squeeze the stools out)

In severe cases, surgery is sometimes needed to remove a large portion of the colon. This is usually a last resort.

Your vet may also advise you to continue treating cat constipation at home. This ongoing management may involve medication, alongside:

  • Ensuring they drink enough water: using water fountains and feeding wet food, for example
  • Regular grooming to help prevent furballs, especially in longhaired cats
  • Litter tray attention: for example ensuring the tray is always clean, using the best cat litter box and a litter your cat likes and ensuring you have one litter tray per cat, plus one extra. 

Your vet may also advise you to change your cat’s diet or recommend some home remedies for cat constipation.

What to feed a cat with constipation 

Cats with constipation usually need a high fibre diet, although this is not always the case. Due to the amount, and types, of fibre in some of the foods we might eat to naturally increase our fibre intake (such as pumpkin), these foods are not generally recommended for cats. The amount you would need to feed to make a difference is usually unrealistic. (And remember that there are some human foods that are poisonous to cats). Instead, your vet will be able to recommend a high-fibre diet or a fibre food additive. Wet food is also beneficial in constipation, to help your cat stay hydrated. 


Cat constipation isn’t pleasant for anyone. There are many possible causes, with some being more serious than others. Constipation can also lead to more serious problems if left untreated. This means it’s important that you take your cat to a vet for diagnosis and a treatment plan, before trying treatment at home.

Dr Sarah-Jane Molier BVM&S MRCVS

Sarah-Jane Molier graduated in 2009 and has been enjoying life as a vet ever since. She currently works as Head Veterinarian in a small animal practice. Sarah-Jane particular enjoys internal medicine, alongside her managerial role. When not working in practice Sarah-Jane enjoys sharing her knowledge and helping pet parents by writing on a wide variety of animal health and medicine topics. In her spare time Sarah-Jane loves walking Nero (her rescue dog), gardening with her two young children and reading.