Biotic's Gain

A meal moves through a dog in stages. Very little happens in the mouth, because dog saliva contains almost no starch-digesting enzyme and most dogs swallow food in barely chewed pieces. The real work starts in the stomach, which is strongly acidic and holds the meal for a few hours while it is broken down into a soft slurry. That slurry is released gradually into the small intestine, where enzymes finish the job and nearly all of the protein, fat, starch and vitamins are absorbed. What is left passes into the large intestine, where water is reclaimed and a large bacterial population ferments the remaining fibre. From bowl to back garden usually takes somewhere between six and ten hours.

The mouth does less than you would think

People chew their food into a paste and start digesting starch before they swallow, because human saliva is rich in amylase. Dogs are built differently. Their saliva is mostly there to lubricate, their teeth are shaped for shearing and crushing rather than grinding, and a hungry dog will happily swallow a kibble whole. If your dog appears to eat a bowl of food without touching it with a tooth, that is ordinary behaviour rather than greed.

It does have one practical consequence. Because so little breaking-down happens in the mouth, the speed of eating is set almost entirely by how fast the dog can swallow, and a dog that empties a bowl in fifteen seconds swallows a good deal of air with it. That is where slow feeders, puzzle bowls and scatter feeding earn their keep.

The stomach: acid, and waiting

A dog’s stomach is strongly acidic during a meal, considerably more so than the resting pH most people imagine, and that acid does two jobs at once. It begins unravelling protein so that enzymes can get at it, and it makes the stomach an inhospitable place for most of the bacteria arriving on food. The muscular walls churn the whole lot into a slurry.

The stomach then empties in a controlled trickle rather than all at once, typically over a few hours, and what it holds changes the timing. Fatty meals sit longer than lean ones, dry food generally leaves more slowly than wet, and a large single meal takes longer to clear than the same quantity split in two. This is the stage where most timing questions get answered: it is why a dog fed a big meal straight before strenuous exercise is uncomfortable, and why an empty stomach in the small hours can lead to the bile-stained vomit some dogs bring up before breakfast.

The small intestine does nearly all the absorbing

As the slurry leaves the stomach it meets enzymes from the pancreas and bile from the liver and gallbladder. The pancreas supplies the amylase that saliva did not, along with enzymes for protein and fat; bile acts as a detergent, breaking fat into droplets small enough to work with. Along the wall of the small intestine, millions of tiny finger-like projections give a very large surface area for a relatively short tube, and this is where the great majority of amino acids, fatty acids, sugars, vitamins and minerals cross into the bloodstream.

A dog’s small intestine is short compared with a grazing animal’s, which fits an animal evolved to eat concentrated, digestible food rather than grass. It also means there is not much slack in the system: when something moves through faster than usual, absorption has less time to happen, and the result turns up at the other end as a softer stool.

The large intestine and the bacteria that live there

Whatever the small intestine could not absorb passes into the large intestine, and this is the part most owners never think about. Two things happen here. Water and electrolytes are reclaimed, which is what turns liquid contents into a formed stool, and the resident bacteria ferment the fibre that no dog enzyme can touch.

That bacterial population is large, settled, and specific to the individual dog and its diet. The bacteria are not passengers: fermentation of fibre produces short-chain fatty acids that the cells lining the colon use as fuel, so the gut wall is partly fed by its own residents. This is also the mechanism behind the words on a supplement label. Prebiotics are the fibres that feed those bacteria, probiotics are live bacteria themselves, and postbiotics are the substances bacteria produce. Our guide to prebiotics, probiotics and postbiotics sets out the difference properly.

How long the whole journey takes

Total transit time in a healthy adult dog is commonly put at six to ten hours, though individual dogs sit well outside that range and size, age, diet and activity all shift it. Small dogs tend to be quicker than giant breeds, puppies quicker than seniors, and a wet-food diet quicker than a dry one.

The useful thing about knowing the rough timing is that it tells you where to look. A dog that vomits shortly after eating is telling you something about the stomach stage; loose stools the following morning point further along the tract; and a change you made to the food yesterday may not show up until this evening at the earliest. It also explains why judging any dietary change over a day or two is pointless. Give a new arrangement a week or two of steady feeding before you decide anything, and change one thing at a time.

The everyday variables that matter most

Once you can picture the tract, the practical list is short. Keep portions consistent and weigh them rather than guessing with a scoop. Split the daily ration into two meals for most adult dogs, more for puppies. Count treats and chews as part of the day’s food, because they are the most commonly overlooked variable in a dog whose stools have changed. Make any change of food gradually over a week to ten days, which is covered in detail in our piece on why changing a dog’s food upsets their stomach. Keep water available. And in a multi-dog household, feed separately, or you have no idea who ate what.

Where a complementary feed fits

Biotic’s Gain Probiotics for Dogs are soft chews containing prebiotics, probiotics and postbiotics, 120 chews to a pack, fed alongside a dog’s normal food according to the feeding guide on the pack, which is sized by body weight. They are a complementary feed, not a complete diet and not a medicine: a complementary feed is fed in addition to a complete food, and it cannot claim to treat, prevent or cure anything. We describe what is in the chews and leave it at that, which is the honest position for any product of this kind.

When to speak to your vet

Book an appointment rather than adjusting the food if your dog has repeated vomiting, diarrhoea lasting more than a day or two, blood in either, a swollen or painful abdomen, unproductive retching, a drop in appetite or weight, or straining without passing anything. A dog that is flat, feverish or drinking noticeably more than usual needs the same. Do not give human anti-diarrhoeal or anti-sickness medicines unless your vet has told you to. If you are unsure whether something you are seeing is a normal variation or a problem, ask your vet, because that is exactly the sort of question they would rather answer early.

Our upset tummy guide collects the practical side in one place.

Biotic’s Gain chews are a complementary feed for dogs, not a medicine, and are fed alongside a complete and balanced diet. Follow the feeding guide on the pack. If your dog is unwell, on medication or under veterinary care, speak to your vet before adding any supplement.