Biotic's Gain

A dog’s gut holds a working population of bacteria that has settled around whatever they have been eating for months. Swap the food overnight and that population is suddenly handed a different mix of protein, fat and fibre, and it takes time to adjust — which is where the loose stools, the wind and the rumbling come from. It is usually the speed of the change rather than the new food itself that causes the trouble. Introducing the new food gradually across seven to ten days, mixed in rising proportions with the old, gives the gut a chance to keep up. Anything severe, or still going after a day or two, is a call to the vet rather than something to wait out.

What is actually living in there

A dog’s digestive tract is not a plain tube that food passes through. The large intestine in particular carries an enormous population of bacteria, and those bacteria do real work: they ferment the fibre that the dog’s own enzymes cannot break down, and they occupy the space and the food supply that would otherwise be available to less welcome organisms.

That population is not fixed. It shifts to suit the diet it is being fed, because whichever bacteria are best at handling the food coming through will multiply fastest. A dog who has been on the same recipe for a year has a gut community that is thoroughly specialised in that recipe.

Why a sudden swap causes trouble

Change the bowl overnight and two things happen at once. The dog’s own digestive enzymes meet a different balance of protein, fat and carbohydrate than they have been geared up for, and the bacterial population downstream meets a fibre source it is not set up to ferment efficiently.

The result is food arriving in the large intestine less completely digested than usual. Fermentation goes up, gas goes up, water balance in the gut shifts, and you get soft or loose stools, more wind than usual and an audible tummy. None of that means the new food is bad. It usually means it arrived too fast.

Fat content is worth singling out. A jump to a noticeably richer food is one of the most common reasons a switch goes badly, because fat is the part of the meal that most readily overwhelms the process if the amount changes sharply.

What a proper transition looks like

The standard approach is to blend the two foods and shift the ratio over a week to ten days. A straightforward version:

• Days 1 to 3: about a quarter new food, three quarters old
• Days 4 to 6: half and half
• Days 7 to 9: about three quarters new food, a quarter old
• Day 10: all new food

Mix the two together in the same bowl rather than feeding one at one meal and the other at the next, so each meal is a small step rather than a series of jolts. And watch the stools as you go. If they soften at the halfway mark, hold at that ratio for a few extra days instead of pressing on to the next stage — there is nothing magic about ten days, and a slower transition costs nothing but patience.

When to go slower still

Some dogs deserve a fortnight rather than a week. Puppies are still establishing their gut population and tend to react more visibly. Older dogs often handle change less comfortably than they did at three. Dogs with a known history of a sensitive digestion have usually taught their owners this already. And a dog who has recently been unwell, or has come off a course of medication, should be moved on to anything new at whatever pace your vet advises rather than on a schedule from a blog.

It is also worth not stacking changes. A new food, a new treat, a house move and a stay in kennels in the same fortnight leaves you with no idea which one caused what.

The things that quietly undo a careful switch

Owners often transition the main food impeccably and then hand over something else entirely on the side. Treats, dental chews, training rewards and the odd bit of whatever is being cooked all arrive in the same gut. If you are mid-switch, keep everything else the same so the only variable is the bowl.

Multi-dog households have a second problem: dogs help themselves to each other’s bowls, and the one you are transitioning carefully may be eating the other one’s food wholesale. Feed separately for the duration. It is also worth checking that nobody else in the house is topping the dog up out of kindness, which is a remarkably common explanation for a switch that appears to be going wrong for no reason.

Where a pre, pro and postbiotic chew fits

Our Probiotics for Dogs chews are a complementary feed, which in feed law means they are fed alongside a complete diet and are not a food in themselves. They combine prebiotics, which are the fibres gut bacteria ferment; probiotics, which are live bacteria; and postbiotics, which are the by-products left behind when bacteria ferment prebiotics. There are 120 soft chews in a pack and the feeding guide is sized to the dog’s weight.

That is a description of what is in the pack, not a promise about what will happen. A complementary feed cannot claim to treat, prevent or cure anything, and we do not ask it to. If you want the plain-English version of how the three parts differ, the article linked below goes through it properly.

When it stops being a food change and needs the vet

A bit of softness for a day or two during a transition is ordinary. Ring your vet if you see blood in the stool or black tarry stools, repeated vomiting, a dog who is flat, weak or off their water, obvious pain or a tense abdomen, or diarrhoea that is watery rather than merely soft.

Ring sooner rather than later for puppies, very small breeds and older dogs, who lose fluid faster and have less in reserve. And if the upset simply carries on past a couple of days, stop guessing at recipes and get an appointment — a persistent change in a dog’s digestion deserves a proper look rather than another bag of food.

Your vet knows the dog, the history and the medication. Anything on this page is general background for owners, and nothing here replaces that conversation.

Biotic’s Gain chews are a complementary feed for dogs, not a medicine, and are fed alongside a complete and balanced diet. If your dog is unwell, on medication or being treated for anything, speak to your vet before adding a supplement.