Why Does My Dog Have Loose Stools? The Best Dog Food to Help
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Part of our Complete Guide to Dog Digestive Health — everything you need to know about digestive problems in dogs and how to solve them through diet.
Loose stools are one of the most common digestive complaints in dogs — and one of the most frustrating for owners. When it happens occasionally it is usually nothing to worry about. But when loose stools are frequent or persistent, diet is almost always the first place to look.
Common Causes of Loose Stools in Dogs
- Sudden food changes — switching dog food too quickly disrupts the gut microbiome
- Food intolerances or protein sensitivities — adverse reactions to specific proteins
- Low protein digestibility — protein not absorbed in the small intestine ferments in the large intestine
- Stress or anxiety — the gut-brain connection is well established in dogs
- Dietary indiscretion — eating scraps, grass or something inappropriate
- GI infection — bacterial, viral or parasitic infections of the digestive tract
For persistent, recurring loose stools with no obvious trigger, diet is usually the root cause.
When to See a Vet
Most episodes resolve within 24–48 hours. See your vet if your dog has had loose stools for more than 2–3 days, shows blood in the stool, is vomiting alongside the diarrhoea, is lethargic, or is very young, senior or has an existing health condition.
For persistent loose stools with no obvious infection, a dietary trial with a highly digestible food is typically the first recommendation.
How Diet Directly Affects Stool Quality
When protein is not effectively absorbed in the small intestine, it travels to the large intestine where gut bacteria ferment it. This fermentation produces compounds including ammonia, phenols and hydrogen sulphide that cause loose, smelly stools and can irritate the gut lining over time.
The answer is not to reduce protein but to feed protein the gut can actually absorb. This is where protein digestibility becomes the key metric.
The Role of Protein Digestibility in Stool Firmness
According to FEDIAF nutritional guidelines, a protein digestibility of 80% or above is considered normal for dog food. Our Hydrolysed Digestive Care Dog Food achieved 95% protein digestibility in a live feeding study at Ghent University Vet School — rated excellent — meaning significantly less undigested protein reaches the large intestine. The result is firmer stools, less gas and reduced odour.
Lignocellulose (2.5%) is also included to further optimise stool consistency and enhance nutrient absorption.
What to Look for in Dog Food for Loose Stools
- High protein digestibility — ideally from hydrolysed protein already broken into small-chain peptides
- Digestive fibre — lignocellulose or similar to support stool firmness
- Postbiotic or prebiotic — to nourish the gut microbiome
- Single protein source — easier to identify and manage if an intolerance is present
- Grain free formulation — removes common dietary irritants
- No artificial additives — colours, flavours and preservatives can aggravate sensitive guts
Our Peptide+ Gastrointestinal Digestive Care covers all of these. For milder sensitivity, our dog food for sensitive stomachs range offers grain free alternatives.
How to Transition
Always introduce a new food gradually over two weeks. Start with 25% new food and 75% old, increasing every few days. Most dogs with diet-related loose stools show clear improvement within 2–4 weeks of full transition.
Frequently Asked Questions
Can dog food cause loose stools?
Yes. Poor protein digestibility is one of the most common dietary causes. When protein is not absorbed in the small intestine it ferments in the large intestine, producing loose, frequent and smelly stools.
What is the best dog food for dogs with loose stools in the UK?
A hydrolysed dog food with high protein digestibility is the most effective dietary approach. Our Hydrolysed Digestive Care Dog Food achieved 95% protein digestibility at Ghent University and requires no prescription.
How long does it take for dog food to firm up stools?
Most dogs see improvement within 7–14 days of switching to a highly digestible food. If there is no improvement after four weeks, consult your vet.
Is grain free dog food better for dogs with loose stools?
Grain free removes common irritants and can help. However if the loose stools are caused by protein intolerance rather than grain sensitivity, a hydrolysed dog food goes further by making the protein itself easier to absorb.
Do I need a vet prescription for dog food for loose stools?
Not always. If the issue is diet-related, a non-prescription hydrolysed food is often just as effective. Our Digestive Care Dog Food is vet-approved but available without a prescription.
Seen It Work
Read how Edith — a dog with chronic digestive flare-ups — recovered after switching to our Hydrolysed Digestive Care Dog Food: Edith's story →
Looking for the full picture? Our Complete Guide to Dog Digestive Health covers causes, signs, dietary solutions and when to see a vet — all in one place.