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In recent years, the practice of feeding dogs raw meat-based diets instead of kibble has grown, in part because raw meat does not require heavy processing or include binders and preservatives that could negatively affect a dog’s health.

Common advice to people is that a diet rich in unprocessed plant foods is best. Among its health benefits are anti-inflammatory benefits that promote heart and gut health and a lower risk of disease, including cancer.

Similarly, some proponents of raw meat-based diets for dogs believe that such regimens reduce the risk of gut health problems, support better dental health, and protect against inflammatory conditions. Advertisements promoting the practice of feeding dogs fresh and raw food are ubiquitous in print and media these days.

But some veterinarians warn against raw food diets for pets. Raw food can contain bacteria that can cause illness in the pets that consume the food, as well as the people who handle and prepare it. Studies have documented that such bacteria can be resistant to antibiotics. Additionally, raw food diets created by pet owners may be nutritionally unbalanced; a 2022 study found nutritional deficiencies in over 90% of dogs on a raw meat-based diet within their study group.

With such considerations as a background, a US research team from Oklahoma State University and the University of Florida conducted the first study to assess how dog feeding regimes can affect anti-inflammatory markers in the gut. Their work appears in Frontiers in Veterinary Science.

In cells, metabolites are small molecules (those with low molecular weight) that are responsible for metabolism and cellular function, maintenance and growth; they make up the cell’s metabolome. Food intake is among the many factors that influence metabolism, and by screening the metabolomic profile, researchers can test for inflammatory diseases in general.

The researchers of this new study compared inflammation in dogs fed kibble-based diets (KD) versus raw meat-based diets (RMBD). The paper states: “We hypothesized that dogs fed RMBD would have changes in their microbiota and metabolome that correlated with changes in faecal and systemic inflammatory markers.”

The study population included 55 clinically healthy adult dogs, all weighing more than 9 kg, that had been fed either a pellet-based diet (n = 27) or a raw meat-based diet (n = 28) for more than one year. according to their owners. Because many owners reported occasionally offering their dogs human food, scraps, and dog treats, the researchers put both groups on restricted diets for 28 days before beginning the testing; “either one brand of kibble (Purina Pro Plan Savor) or RMBD (Titan Blue, Ross Wells) and a single-ingredient treat,” the study explains.

The study noted that starch made up approximately one-third of the food consumption of the KD group, while starch accounted for less than 1% of what the RMBD group consumed due to a lack of dietary plant sources. However, each group ate similar amounts of protein; 3.6 g/kg bw/day for the RMBD group and 3.2 g/kg bw/day for the KD group.

The dogs remained with their owners during the study, and the owners recorded the dogs’ weekly food consumption, with instructions to report any deviation from the study’s prescribed diets. On day 28, the dogs returned to the laboratory for physical examination and blood and stool sampling.

Findings

The team found similar inflammatory markers—including serum metabolites specific for antioxidant and anti-inflammatory functions—in the two groups’ blood samples, but significantly different results in the two groups’ intestinal inflammatory markers. They also observed differences between the groups’ metabolomes and fecal microbiota.

In RMBD dogs, researchers found higher levels of fecal IgA (a mucosal antibody that protects against infection), IgG (an antibody that protects the immune system against previously encountered bacteria and viruses), and IAP (another gut-protecting antibody).

“We theorize that these increases in RMBD-fed dogs may reflect improved gastrointestinal homeostasis and immune function, as well as increased food digestibility,” they wrote.

However, they were unable to determine whether the observed differences were beneficial or not due to the short duration of the study and the inclusion of only healthy dogs. They expected to find a parallel between the different results of faecal inflammatory markers and results of systemic inflammatory markers, but they did not and suggested that this may be the result of a low level of sensitivity of the biomarker.

As next steps, the researchers suggest that larger studies of longer duration, including more sensitive markers — functional assays — may shed more light on the effects of the two diets. They also note that with regard to intestinal inflammation, a study design exposing the same dogs to both diets may reveal the effects of each.