Constipation in Cats

What is constipation?

Constipation can be defined as an abnormal accumulation of faeces resulting in a difficulty in passing bowel motions. This may result in reduced frequency or absence of defecation. The faeces are retained in the large intestine which is called the colon. Since one of the functions of this part of the bowel is water absorption, the retained faeces become hard and dry which makes passage of these even more difficult. Constipated cats strain in an attempt to defecate and this is often painful. Some constipated cats may pass small amounts of liquid faeces.

What causes constipation?

Factors associated with causing constipation include:-

1.  Hairballs, especially in long-haired cats.

2.  Ingestion of foreign bodies.

3.  Obstruction caused by tumours, strictures or masses compressing the large intestine.

4.  Pelvic injuries, most commonly after a road accident, resulting in a narrowed pelvic canal.

5.  Damage of the nerves which cause the colon to contract. This may arise following traumatic damage such as a road accident or may be seen as part of more generalised neurological disease.

6.  In the majority of cases however, there is no obvious cause identified, and the condition is termed idiopathic constipation or idiopathic megacolon.

Constipation is a condition seen most commonly in middle-aged and older cats.

What is megacolon?

This term refers to a dilated and poorly motile colon. Megacolon may be seen as a primary entity or arise following long-term constipation. When the colon becomes distended with faecal material over a prolonged period of time its ability to contract may be reduced or lost resulting in megacolon.

How are constipation and megacolon diagnosed?

In most cases, a diagnosis of constipation can be made on the basis of the clinical signs that the cat is showing. Affected cats usually strain unsuccessfully to defecate and may cry in pain when doing this. Any faeces passed are hard and dry. The cat may also show signs of lethargy, reluctance to eat and vomiting.

"Affected cats usually strain unsuccessfully to defecate and may cry in pain when doing this. Any faeces passed are hard and dry."

Further tests may be needed in order to diagnose the cause of the constipation and these may include radiographs of the abdomen and pelvis in order to look for pelvic injuries, colonic strictures or tumours. Radiographs are also required for the diagnosis of megacolon. Blood tests may also need to be performed to look for systemic disorders that can predispose cats to development of constipation, such as chronic kidney disease and blood electrolyte disturbances.

How can constipation and megacolon be treated?

This varies depending on the cause of the problem, hence, if an obstruction is present, such as a colonic tumour, then surgical treatment of this may be performed.

Initial treatment of a cat with constipation may involve administration of enemas and manual extraction of faeces by a veterinarian. This may necessitate hospitalization and an anaesthetic or sedative. Treatment of dehydration with intravenous fluids may also be needed in severely affected cats. In severely affected cats more than one anaesthetic may be required to remove all the impacted faeces as they become very hard and difficult to remove. If the constipation recurs or becomes a long-term problem then continuous therapy may be needed to prevent recurrence. A wide variety of treatments are available and the aims of these are to enable regular defecation of soft faeces. Altering the diet so that this contains more fibre may be helpful in some cases, other cases respond better to diets designed to result in production of lower volumes of faeces (‘low residue diets’) and lubricating laxatives or stool softeners may also be used in mildly affected cats. Those more severely affected may need drugs that stimulate contraction of the colon. The doses of all of these drugs may need to be altered to produce the desired effect. Ideally, cats should defecate at least once every other day. Over a period of time, resistance to the treatment may be found necessitating an increase in the drug dosage or a change to another therapy. No changes to the treatment protocol should be made without consulting your veterinarian.

In long-haired cats, regular grooming may reduce hair ingestion by the cat and therefore reduce the likelihood of hairballs causing constipation. Encouraging your cat to drink with the use of water bubblers or fountains is useful particularly in cats with kidney failure and other conditions that lead to dehydration. Avoid feeding bones as they can harden the stools and make them more difficult to pass. It is important to ensure that there is always access to a clean litter tray so that frequent defecation is encouraged.

If megacolon develops or if the constipation is severe and medical treatment is unsuccessful then surgery may be advised by your vet. Surgical treatment involves removal of most of the colon. Whilst this may seem a drastic measure it is often very successful and improves the quality of life of your cat – especially in cats that resist medication and are having repeated bouts of painful constipation. Following surgery your cat may have diarrhoea for a short period (days) but this should eventually settle. The surgery should not result in faecal incontinence.

What is the long-term outlook for a cat with this problem?

The long-term outlook obviously varies according to the cause of the constipation, its severity and how easy it is to medicate your cat. Most cats can be adequately managed medically but in those that can’t, surgery is a viable alternative.