“Dogs fed vegan diets clearly had the best health outcomes in this very large-scale study, and these results are consistent with prior studies in this field.” – Prof Andrew Knight Sept 2024
Read the published study here or read more about Prof Knight’s study and the response here.

The most comprehensive study so far by Dr Annika Linde et al published and peer reviewed in April 2024, has demonstrated that dogs fed nutritionally-sound plant-based diets maintain health outcomes just as well. In a few respects health indicators even improved.

This was the most thorough study so far, and one of the longest – the dogs were fed solely plant-based diets for an entire year – just under one tenth of an average dog lifespan, or around seven human years.

The study, published in leading scientific journal PLOS ONE [1], comprehensively assessed the health of 15 dogs by analysing blood cells and biochemistry, blood nutrient levels, urine, veterinary clinical parameters, and monthly pet owner questionnaires. The dogs were fed solely plant-based diets based on pea protein for an entire year – just under one tenth of an average dog lifespan, or around seven human years.

Overweight or obese dogs achieved a healthier weight, whilst the remainder maintained normal weight. No clinically significant changes occurred within blood and urine. Blood levels of essential and non-essential amino acids and vitamins were all generally maintained.

In a few cases, previous deficiencies following a meat-based diet either improved or disappeared, including L-taurine and L-carnitine (important for cardiac health), Vitamin D (indispensable for immunity and bone health), and folate (required to produce red blood cells).

The study was particularly interesting, given recent suggestions that peas might contribute to heart disease in dogs in the US. Although no credible evidence has been found, such concerns have persisted in some quarters. In the current study, dogs were fed pea-based plant-based dog food, for one year. Blood markers of cardiac health were assessed, with no signs of heart disease found. Indeed, in some cases indicators of cardiac health improved.

The results indicate a significant reduction in the categories climate change, acidification, and smog associated with tinned vegan dog food VegDog compared to a meat-based tinned dog food. For climate change, switching to a vegan diet for dogs could significantly reduce annual emissions and help to reduce both the pawprint of a dog and the footprint of its owner. (Sept 24)

Read full published paper here

Studies by Prof Andrew Knight from the University of Winchester show how plant-based diets lower greenhouse gas emissions (GHGs), and use less land and water. Food energy savings mean more people can be fed. His major study published in leading scientific journal PLOS ONE on 04 Oct 2023 has demonstrated very large environmental benefits arising from nutritionally-sound vegan diets – for dogs and cats, as well as people.

After analysing pet food ingredients in detail, as well as food consumed by people, Veterinary Professor Andrew Knight calculated that the world’s dogs and cats consume around 9% of all land animals killed for food, or around 7 billion animals annually, as well as billions of fish and aquatic animals.

Prof Knight calculated that if all the world’s dogs went vegan, it would save more GHGs than all those emitted by the UK, land larger than Mexico, freshwater exceeding all renewable freshwater in Denmark, and would feed around 450 million additional people – more than the entire EU.

This is the latest research published in January 2023 in Veterinary Sciences University of Adelaide. They have brought together the health findings from the 16 recent studies on dogs and cats fed vegan diets.

They concentrated specifically on this fact that – “Much of these data were acquired from guardians via survey-type studies, but these can be subject to selection biases, as well as subjectivity around the outcomes.” ie they had to look at the results subjectively as the answers came from vegan owners themselves who were so passionate about the diet and wanting every result to be positive.

This latest published paper from Australia and Mexico is therefore even more important as they had to conclude from all the evidence that –

Domínguez-Oliva et al. (2023) concluded, “there was no overwhelming evidence of adverse effects arising from use of [vegan pet food] and there was some evidence of benefits. … Much of these data were acquired from guardians via survey-type studies, but these can be subject to selection biases, as well as subjectivity around the outcomes. However, these beneficial findings were relatively consistent across several studies and should, therefore, not be disregarded.”

They advised, “… if owners wish to feed their companion animals vegan diets, a cautious approach should be taken using commercially produced diets which have been formulated considering the nutritional needs of the target species.” [ie. that are nutritionally-sound].

How very positive saying that “there was no overwhelming evidence of adverse effects arising from the use of vegan pet food and there was some evidence of benefits.”

This study of 61 dogs at the University of Guelph by Dr Sarah Dodd et al. (2023) studied 31 dogs fed an experimental vegan diet (‘PLANT’) and 30 fed a commercial meat-based diet (‘MEAT’) for 3 months. Read the study here.

“Bone mineral content and density did not differ from baseline values. Health status was maintained in dogs fed PLANT and Vitamin D2  [which is sourced from non-animal sources including Algae] appeared efficacious in maintaining serum total Vitamin D concentrations and bone mineralisation. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least 3 months.”

“The highest toxic metals concentrations, in general, in animal-based ingredients than plant-based ingredients could be attributed to the potential for the accumulation of these elements in the animal organism. Some elements can accumulate in animal tissues, such as bone tissue, skeletal muscle, liver, kidneys, and spleen, as well as in animal products such as milk, reaching critical concentrations that may imply adverse effects on the health of human beings who consumes these products.”

Read full study here

Excess protein enabled dog domestication during severe Ice Age winters in this published study

Similarity of the dog and human gut microbiomes in gene content and response to diet

The genomics of selection in dogs and the parallel evolution between dogs and humans in this published study

Role of the Microbiota in Immunity and inflammation

The low amino acid LA and grain free GF diet resulted in lower faecal ammonia, indole, and secondary BA concentrations but greater total short chain fatty acids, acetate, propionate, and primary BA concentrations. LA-GF also shifted the faecal microbiota with more abundant Selenomonadaceae, Veillonellaceae, Lactobacillaceae, Streptococcus, Ligilactobacillus, Megamonas, Collinsella aerofaciens, and Bifidobacterium sp., and while a reduction in diversity was noted, all dogs remained healthy.

Read full published paper here