What is it?Cats can go for quite some time without passing faeces. However, over time the water in the faeces starts to be reabsorbed through the colon, leading to dry, hard faeces. The colon is the part of the gut that absorbs water after digestion, and stores faeces for a short time until they are passed out through the anus. When a cat is constipated, they pass hard, dry faecal pellets, if anything; often accompanied by straining and pain.
Why is it important?
Constipation may lead to other more serious conditions, such as severe blockage (obstipation). Constipation can result in considerable pain and distress for the cat. If the constipation is left untreated, the condition may worsen and the colon may be stretched to its limit, leading to permanent damage – a ‘megacolon’. This can have a serious impact on the cat’s quality of life, and can be life limiting.
There may also be underlying causes of constipation, such as kidney disease, that need diagnosing and treating.
What is the risk?
Any cat can develop constipation, but there are certain specific risk factors that mean it is much more likely. These risk factors include:
What happens to the cat?
Constipation can take days or weeks to develop. The cat experiences pain trying to pass faeces. Vomiting may occur due to the gut becoming stretched by the accumulation of dry faeces. Diarrhoea may occur as well, due to only small amounts of soft faeces being able to pass the obstruction, and there may be blood in the faeces. The cat often refuses to eat, causing further dehydration.
The owner may notice that the cat is frequently straining to try and pass faeces, but nothing is coming out. It is worth noting that inability to urinate (another serious condition) can appear as if the cat is constipated.
How do you (the vet) know what is going on?The cat will be examined in the clinic. The owner will be asked questions about the cat’s diet and lifestyle, and about how the problem has developed. A large mass of faeces can often be felt on examination by feeling the cat’s abdomen. The cat will often be dehydrated at this point. Blood tests to check for underlying causes such as kidney disease are often needed, and X-rays (radiographs) of the cat’s abdomen will show a blockage of the colon with faeces, allowing the vet to check if the colon is abnormally large (megacolon).
What can be done?
Fluid therapy (an intravenous drip) is often needed to rehydrate the cat. This also has the effect of rehydrating the gut and adding water to the faeces.
Depending on how severe the impaction of faeces is, an enema may need to be applied with the cat under sedation. Warm water and lubricant are usually used for this. If the faecal impaction is very severe it may need the faeces to be gently broken up and removed by inserting a long catheter and injecting warm water and lubricant around the obstruction. The vet then gently manually breaks up and removes the faeces from the colon. Stool softeners and laxatives such as lactulose are also useful in the diet to help a cat who is prone to constipation.
Sometimes a diet high in fibre is recommended, however if the cat has a seriously dilated megacolon, then a low residue, high energy diet is preferred. This is because the muscle function of the colon is no longer effective, so high fibre diets may make things worse.
Medications such as cisapride, which stimulates the gut to move, can be helpful. Sadly, in the most serious cases, the cat may require surgery to remove their colon entirely.