Dog - Diarrhoea

Veterinary surgeons are frequently consulted about dogs with diarrhoea. Normally dogs pass faeces up to three times a day and they are usually formed, i.e. retain their shape.

What is diarrhoea?

The criteria are:

• Unformed faeces
• Increase in frequency
• Increase in volume

Thus if your dog is only passing a soft stool once or twice a day it is strictly not diarrhoea but could be termed a loose bowel.

What causes diarrhoea?

Diarrhoea is not a disease in itself. It is a sign of a bowel problem. This can vary from simple dietary indiscretion, e.g. eating a rotting bone found in the garden to potentially fatal illnesses such as cancer. Many mild cases of diarrhoea can be resolved very quickly with simple treatment. Without treatment even simple cases can result in serious consequences. This is because diarrhoea results in severe fluid loss in the body. This can lead to life threatening dehydration.

Are there any signs that indicate the seriousness of the condition?

Depending upon the severity of the diarrhoea, any or all of the following signs may be present.

• Vomiting
• Loss of appetite
• Abdominal pain
• Pyrexia (fever)
• Lethargy
• Bloody and/or watery diarrhoea occurring very frequently

Are dogs that scavenge more likely to have bouts of diarrhoea?

So-called ‘non specific acute diarrhoea’ is very common in dogs that scavenge. This may be due to bacterial contamination of the food or food containing bacterial toxins. Sometimes the toxic products are due to decomposition of the food itself (so-called food poisoning). Provided serious dehydration is prevented these cases generally last only a few days and often clear up spontaneously.

How do I prevent dehydration? My dog vomits as soon as he drinks.

This is not uncommon since vomiting often accompanies diarrhoea. It is essential to control fluid intake. Offer only small quantities at a time. We can provide products which, when dissolved in the drinking water and offered in small quantities, will help to control vomiting and to prevent dehydration.

What are the main causes of diarrhoea?

Scavenging has already been mentioned. Bacterial infections are probably the most important. Some, e.g. salmonella and campylobacter, can cause serious enteritis (inflammation of the bowel) and can affect humans, i.e. is zoonotic.

Other causes include irritant poisons, dietary allergies and viral infections, (e.g. canine distemper and parvovirus). With the latter infection there is usually also severe vomiting and dehydration. Parvovirus diarrhoea frequently contains blood (dysentery).

Haemorrhagic gastroenteritis (HGE) frequently results in dysentery. The cause of HGE is not definitely known although certain bacteria and bacterial toxins and allergic conditions can be responsible. Young adults of toy and miniature breeds appear to be most at risk.

Any suspicion of haemorrhagic gastroenteritis should be treated as an emergency. Call us without delay.

Please ask for the handout on HGE.

What causes dehydration?

As food passes through the digestive tract it is mixed with digestive juices at the rate of approximately one litre for every 11 kg body weight. In normal circumstances the majority of this fluid is reabsorbed during the passage through the gut. However if the bowel is irritated, e.g. by viruses, bacterial toxins, irritants, dietary allergies, etc. it responds by trying to move the contents through as quickly as possible. There is then not sufficient time for reabsorbtion of fluid. Food usually takes between 5 and 10 hours to pass through the bowel depending on its type, the age and activity of the dog etc. When there is increased motility (intestinal hurry) this can be reduced to as little as 20 minutes!

Are there other types of diarrhoea?

Chronic or long standing diarrhoea can be a problem in some dogs. If for any reason food is not properly digested or absorbed it remains in the intestine and attracts fluid. The dog then passes soft faeces and is often hungry despite increased intake. Weight loss is a common sign. Sometimes the undigested material ferments in the bowel. This produces large amounts of gas which the dog will pass.   See handout on Exocrine pancreatic insufficiency [EPI].

Sometimes flatus (wind) and mild chronic diarrhoea will occur with one particular type of commercial food and not with another. Therefore it is always worthwhile attempting to select a food which suits your dog and then feeding it exclusively. In this way a lot of dietary problems are minimised.

What does diagnosis involve?

Investigation usually involves radiography (x-rays) with or without the use of barium. Ultrasound scans, blood tests and bacterial cultures are also commonly performed. In certain cases exploratory abdominal surgery and biopsies of the intestinal tract may be necessary.

What is the treatment?

If your dog does not appear ill irrespective of whether the diarrhoea is acute or chronic, the cause may be simply dietary indiscretion. This is the most common cause of diarrhoea in the dog. Other common problems involve infection with bacteria, viruses and intestinal parasites. Once diagnosed these cases are treated with appropriate drugs to eliminate the cause and also to control mobility and relieve inflammation. Special diets are often prescribed. If this does not bring about improvement, more specialised tests may be necessary.

In the majority of cases of diarrhoea improvement can be expected following simple medication. In more obstinate cases long term treatment including special medications, diets or surgery may be indicated.

Please do not hesitate to discuss your concerns with us.