Fewer Bags, Healthier Dogs: What the Science Really Says About Raw Feeding and Stool Health

It’s usually one of the first things raw-feeding owners notice. Within days of switching their dog to raw food, the morning walk looks different. The poo bags are smaller. There are fewer of them. And the olfactory assault that once preceded the bin trip has eased considerably. Most owners chalk this up to a pleasant coincidence — a nice side effect of the change.

But it isn’t a coincidence at all. It’s one of the most direct and measurable signs that something meaningful is happening inside your dog’s body. What ends up in that bag is what your dog couldn’t use. And the science of why raw-fed dogs produce less waste — firmer, less frequent, and less pungent — is now well documented in peer-reviewed research.

It turns out the humble poo is quite the health report card. And raw-fed dogs consistently score well.

Your Dog’s Stool as a Health Indicator

Vets have long used fecal scoring as a diagnostic tool. Stool consistency, colour, volume, frequency, and odour all provide meaningful information about what’s happening in the digestive tract. A well-formed, moderate-sized, low-odour stool produced once or twice a day is considered the ideal. Loose, voluminous, frequent, or particularly pungent stools suggest that something in the digestive process isn’t working as efficiently as it should be.

For generations, dog owners were told that a good dry kibble produced ‘firm stools’ and that this was a sign of quality. What the research now makes clear is that fecal firmness is only one part of the picture — and that the volume, frequency, and composition of your dog’s stools reveal as much about what their food is actually doing as any marketing claim on a bag.

The Digestibility Gap: Less Out Because More Was Used

The most striking data in this area comes from a 2021 study by Tanprasertsuk and colleagues, published in Translational Animal Science. Researchers compared dogs fed a chicken-based extruded dry kibble with dogs fed a range of chicken-, beef-, pork-, and turkey-based fresh food diets over a standardised period.

The fecal output results were stark. Dogs fed the fresh diet defecated just 1.2 times per day on average, compared to 1.7 times per day for kibble-fed dogs — a 30 per cent reduction in defecation frequency. More significantly, the daily dry matter fecal output of fresh-fed dogs was 24 grams per day, compared to 47 grams per day for kibble-fed dogs. That’s roughly half the dry waste.

“Fresh-fed dogs produced approximately half the dry matter fecal waste of kibble-fed dogs — and defecated 30% less frequently.” — Tanprasertsuk et al., Translational Animal Science, 2021

The kibble-fed dogs were also burning through significantly more calories in their stools — 189 kcal per day versus 92 kcal per day in fresh-fed dogs. Nearly double the caloric waste. The conclusion was clear: the apparent total tract digestibility of dry matter, protein, fat, and energy were all significantly lower in the kibble diet than in any of the fresh diets tested.

A 2018 study by Algya and colleagues at the University of Illinois, published in the Journal of Animal Science, found the same pattern. Mildly cooked and raw diets produced significantly higher digestibility of crude protein, fat, and energy compared to the extruded diet. Dogs on raw and fresh diets were extracting more from every meal — and leaving considerably less behind.

Why Kibble Produces More Waste

To understand why, it helps to understand what happens to food during the extrusion process used to make dry kibble. Ingredients are subjected to very high temperatures and pressures, which can degrade heat-sensitive proteins, reduce the bioavailability of certain fats and amino acids, and chemically alter some nutrients. The result is a product that, despite being engineered to meet nutritional minimums on paper, may not deliver those nutrients with the same efficiency as a minimally processed or raw equivalent.

Kibble also tends to be high in starchy carbohydrates — used as a binding agent in the extrusion process — which dogs are not particularly well equipped to digest. Undigested starch passes into the large intestine where it is fermented by bacteria, producing the fermentation by-products that contribute to fecal bulk, gas, and the characteristic odour of processed-food stools.

Raw and whole-food diets, by contrast, are lower in fermentable starch, higher in moisture, and contain proteins and fats in forms that are readily recognised and absorbed by the digestive system. More goes to work inside the dog. Less ends up on the pavement.

What the Fecal Metabolome Tells Us

Beyond volume and firmness, researchers have examined what is actually in the stools of raw-fed versus kibble-fed dogs at a molecular level — a field of study known as fecal metabolomics. The results are illuminating.

A 2018 study by Schmidt and colleagues, published in PLOS ONE, analysed the fecal metabolome of 27 dogs fed a Bones and Raw Food (BARF) diet and 19 commercially fed dogs using advanced metabolomics techniques. The fecal profiles of the two groups were strikingly different. BARF-fed dogs showed elevated levels of amino acid-derived metabolites in their stools, reflecting a diet rich in bioavailable protein. Commercially fed dogs showed metabolomic profiles more consistent with carbohydrate fermentation.

In practical terms, this helps explain the odour difference. The pungent smell associated with processed-food stools comes largely from the fermentation of undigested carbohydrates and low-quality proteins in the large intestine. Raw-fed dogs, with less undigested starch and more readily absorbed protein, produce fecal metabolomes with a markedly different signature — one that translates, in everyday experience, to a considerably less offensive bin bag.

Consistency and Clinical Health

A 2021 clinical study by Sciascia and colleagues, published in the Journal of Animal Science, compared hematology, serum biochemistry, and clinical health scores in 28 raw-fed and 27 kibble-fed client-owned dogs. Among the findings: raw-fed dogs showed slightly firmer fecal consistency compared to kibble-fed dogs, alongside measurably better clinical composite health scores.

It is worth noting that ‘firmer’ in this context is relative and nuanced. Some studies have found raw diets produce slightly moister stools than extruded kibble — which makes intuitive sense, given that raw food has a significantly higher moisture content than dry kibble. The key distinction is between total wet weight (which may be similar or slightly higher) and dry matter output (which is consistently lower in raw-fed dogs). When moisture content is accounted for, raw-fed dogs produce meaningfully less actual digestive waste.

What This Means for Your Dog

The science is consistent across multiple independent studies: raw-fed dogs produce less fecal dry matter waste, defecate less frequently, and have a fecal metabolome that reflects better nutrient utilisation and less undigested fermentation. These are not trivial findings. They speak directly to how efficiently a dog’s body is running — how much of what goes in is genuinely nourishing them, and how much is being wasted.

The morning walk, it turns out, has always been telling us something. We just needed the science to explain it properly.

At Wolfie, every batch we handcraft from the seasonal, whole ingredients of Baronscourt Estate is designed to be genuinely used by your dog’s body — not just passed through it. Real food, prepared with care, absorbed with purpose. That’s what [wildly nourishing](https://hellowolfie.com/why-raw-feeding-could-be-the-best-decision-you-make-for-your-dog/) really means.

Ready to make the switch? [Learn more about transitioning your dog to raw food](https://hellowolfie.com/raw-feeding-guide/) or explore how [raw feeding supports your dog’s gut health](https://hellowolfie.com/whats-really-happening-in-your-dogs-gut-the-science-behind-raw-feeding/).

References

Tanprasertsuk, J., Tate, D.E., Perry, C.L., et al. (2021). Apparent total tract nutrient digestibility and metabolizable energy estimation in commercial fresh and extruded dry kibble dog foods. Translational Animal Science, 5(3), txab071.

Algya, K.M., Cross, T.L., Leuck, K.N., Kastner, M.E., Bauer, L.L., Swanson, K.S., & Fahey Jr, G.C. (2018). Apparent total-tract macronutrient digestibility, serum chemistry, urinalysis, and fecal characteristics, metabolites and microbiota of adult dogs fed extruded, mildly cooked, and raw diets. Journal of Animal Science, 96(8), 3270–3286.

Schmidt, M., Unterer, S., Suchodolski, J.S., et al. (2018). The fecal microbiome and metabolome differs between dogs fed Bones and Raw Food (BARF) diets and dogs fed commercial diets. PLOS ONE, 13(8): e0201279.

Sciascia, Q.L., Otten, W., Metzler-Zebeli, B.U., et al. (2021). Clinical health markers in dogs fed raw meat-based or commercial extruded kibble diets. Journal of Animal Science, 99(6), skab133.