The Power Of Prebiotics: Why Your Dog Needs More than Probiotics

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Prebiotics are fibres that a dog cannot digest but its gut bacteria can. They feed the beneficial bacteria already living in the gut. This page lists the natural sources, how much to give and when to see a vet.

Natural prebiotics for dogs

  • Green seaweed, such as Ulva, which is high in soluble fibre
  • Chia seeds, soaked in water before feeding
  • Cooked, fibre-rich vegetables such as pumpkin and sweet potato

Seaweed amounts

Stoolrite is a single-ingredient green seaweed powder, sprinkled on one meal a day: 1 level teaspoon for a small dog (under 10 kg), 2 for a medium dog (10 to 20 kg) and 3 for a large dog (over 20 kg). BioFunction8 is a blend of seaweeds, organic chia seeds, chamomile and marshmallow. It comes with a 2 gram scoop, and the feeding guide is on the pack and product page.

With either product, start with a small amount and build up to the recommended dose. Seaweed contains natural iodine, so these products are not recommended for dogs with thyroid problems. If you feed other seaweed products as well, keep seaweed below 5% of the total feed.

When to see a vet

Add fibre gradually. If your dog has diarrhoea that lasts more than a day or two, or has blood in the stool, vomiting or low energy, see your vet before adding anything new. Prebiotics are not a treatment for ongoing digestive problems.

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Probiotics and prebiotics: the difference

Probiotics are live bacteria, such as Lactobacillus and Bifidobacterium, that add to the beneficial microorganisms in your dog's gut. The best evidence for them is in diarrhoea linked to stress or antibiotics. Prebiotics are not living organisms. They are plant fibres that feed the bacteria in the gut, helping them grow and stay active.

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Why prebiotics matter

Probiotics only help if the gut can support them, and prebiotics provide the food. Feeding the bacteria your dog already has restricts harmful bacteria and supports normal digestion. Different fibres feed different bacteria, so a mix of sources works better than one.

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Chia seeds

Chia seeds come from Salvia hispanica, a plant native to Mexico and Guatemala. They are high in soluble fibre, which gut bacteria ferment. Dry chia absorbs many times its weight in water, so soak the seeds in water for at least 30 minutes before feeding. This lowers the risk of them swelling in the gut. Start with a small amount, build up slowly, and ask your vet for an amount that suits your dog, especially if your dog has a health condition.

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Green seaweed

There are thousands of seaweed varieties, and they fall broadly into red, brown and green groups. Green seaweeds from the Ulva family grow in shallow coastal waters around the world and are high in soluble fibre. Ulvan, the main polysaccharide in Ulva, acts as a prebiotic in laboratory fermentation tests with human gut bacteria and in mouse studies. Results vary between studies, and we are not aware of a study in dogs.

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