How can I treat my gundog’s diarrhoea? What causes it?

Q: “Can you explain to me why my gundog gets a stomach upset? What causes diarrhoea in dogs and how can I stop my gundog getting it?

Diarrhoea in dogs – the symptoms and the causes

Diarrhoea is defined as increased water content of faeces, leading to changes in frequency of passing, fluidity or volume 
of faeces. This occurs because of one or 
more of:

• Altered motility of the bowel
• Reduced absorption of water
• Increased secretion of water
• Altered permeability of the bowel lining

There are numerous ways to separate different types of diarrhoea into groups, which can be useful for diagnostic purposes.

Is it the upper or lower bowel?

Generally when the upper bowel, or small intestine, is affected, you will see:

• Mild increase in frequency of passing faeces
• Large volume of faeces
• Colour changes, including ‘changed’ blood
• Weight loss (as absorption of nutrients 
is affected)

When the lower bowel, or large intestine 
is involved, you expect:

• Increased frequency to more than three times daily.
• Mucus (jelly-like or shiny covering)
• Fresh red blood (not black)
• Urgency and straining (so more ‘accidents’)
• No loss of weight

There are many different causes for upset stomachs in dogs

Causes of diarrhoea in dogs

The list of causes of diarrhoea in dogs is nearly endless. The dog’s recent history can be crucial. For example, has it been scavenging? Has there been any change of diet? Has the dog been dewormed effectively? Is there the possibility of another disease? Are in-contact animals (or humans) affected?

Perhaps one of the most important aspects is whether the problem is acute (that is to say a sudden onset, continuous and of less than a week’s duration) or chronic (present for more than two weeks and comes and goes).

Acute diarrhoea

The causes can be broken down broadly into:

• Dietary indiscretion
• Ingestion of toxins
• Bacterial infections (campylobacter, salmonella, E. coli)
• Viral infections (parvovirus, coronavirus)
• Parasitic infections (roundworms, hookworms, whipworms, giardia)
• Food allergy
• Irritable bowel syndrome
• Other disease processes
• Foreign body (though generally they 
stop passing faeces)
• Abdominal catastrophe (twisted bowel)

Treatment may involve faecal culture to look for infectious agents, withholding food for 24 hours (water little and often), the 
use of gut protectants and judicious use 
of motility modifiers, such as loperamide. 
It is also essential to worm regularly.

Chronic diarrhoea

I have never been too sure exactly when acute diarrhoea becomes chronic. This is another problem, so requires another list:

• Other diseases (such as pancreatic insufficiency, heart issues, Addison’s disease)
• More infections (Yes, as previous)
• Dietary intolerance
• A lack of antibiotics
• Tumours (especially lymphoma and intestinal cancers)
• Irritable bowel syndrome (again)
• Foreign body

All of the aforementioned should highlight how complicated diarrhoea can be.

What a vet should investigate

• Faecal culture (a must in severe cases)
• Pancreatic tests (for inflammation or insufficiency)
• Blood cell count (evidence of infection, parasites)
• Biochemistry testing (liver, kidney, Addison’s disease)
• Urine sampling (evidence of organ disease, protein loss)
• Serum folate and cobalamin (B12) levels (distinguish maldigestion and malabsorption)
• Intestinal biopsies (a last resort)

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Which dog breeds are more prone to diarrhoea?

Some breeds are prone to specific problems that cause diarrhoea. These include: gluten-sensitive enteropathy in Irish setters; familial protein-losing enteropathy of soft wheaten terriers; and granulomatous colitis of boxers, French bulldogs and bulldogs (which I include just in case you were thinking of straying).