Cat - Constipation

What is constipation?

Constipation can be defined as an abnormal accumulation of faeces in the colon and rectum (large intestine).  This may result in reduced frequency or absence of passing of faeces, one of the functions of this part of the large intestine is water absorption, so when it does not work the retained faeces become hard and dry which makes passage of these even more difficult. Constipated cats may frequently 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 (tight bands of fibrous tissue) 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 to the colon which means this part of the intestine cannot function properly. 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 colon with reduced function. Megacolon may be seen as a primary entity or arise following prolonged 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.

Further tests may be needed in order to diagnose the cause of the constipation and these may include x-rays of the abdomen and pelvis in order to look for pelvic injuries, colonic strictures or tumours. Radiographs (x-rays) are also required for the diagnosis of megacolon. Blood tests may also need to be performed to look for other diseases 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 veterinary surgeon. The latter of these may necessitate an anaesthetic or sedative. Treatment of dehydration with intravenous fluids may also be needed in severely affected cats. If the constipation recurs or becomes a longterm 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).  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 veterinary surgeon.

In long haired cats, regular grooming may reduce hair ingestion by the cat and therefore reduce the likelihood of hairballs causing constipation.

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 at controlling this then surgery may be advised by your vet. Surgical treatment involves removal of most of the colon which initially will result in diarrhoea since the colon is responsible for water removal from faeces. Over a period of time, this usually improves. The surgery should not result in loss of bowel control.

What is the longterm outlook for a cat with this problem?

The longterm outlook varies tremendously according to the cause of the constipation, however, most cats can be adequately managed without having to resort to surgery.