Veterinær info

-- Breaking news, 18 Jun. 2022 –

Vegan dogs live longer:
new studies support nutritionally-sound vegan dog food

Key new studies have emerged, supporting nutritionally-sound vegan dog food. Dodd et al. (2022) collected dietary information from 1,189 dog guardians, including 357 feeding solely vegan diets, who fed these diets for 3 years on average. Vegan dogs were reportedly more likely to enjoy very good health, and less likely to suffer ocular, gastrointestinal and hepatic (liver) disorders. No health disorders were more likely, and longevity of previously-owned dogs was reportedly 1.5 years greater, when fed purely vegan diets.

Davies (2022) surveyed 100 dog guardians who had switched to a nutritionally complete vegan dog food designed by UK veterinarians. Clear improvements after 3-12 months were reported in coat glossiness, dandruff and erythema (skin inflammation), itchiness (scratching; pruritus), external ear canal crusting (otitis externa), faecal consistency, defaecation frequency, flatus frequency and antisocial smell, anxiety, aggressive behaviour and coprophagia (stool consumption).

There are now eight studies or veterinary masters theses, examining health outcomes in dogs maintained on vegan or vegetarian diets (all at: https://sustainablepetfood.info/vegetarian-canine-diets/#3). Seven studies now support the use of these diets. The weight of evidence now overwhelmingly supports the use of nutritionally sound vegan dog food.

Our own recent study (Knight et al, 2022: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0265662) studied 2,536 dogs fed vegan or meat-based diets for at least one year. Being a very large-scale study, our results confer a high degree of statistical reliability. We included guardian opinions of health – which are not always reliable – as well as a range of more objective data, such as prevalence of medication usage. We pooled many different indicators of health, concluding the healthiest and least hazardous diets for dogs are nutritionally sound vegan diets.

Semp (2014; n = 174 for history, n = 20 for clinical examinations and haematology) and Keimer (2019; n = 250 for history, n = 40 for clinical examinations and haematology) also demonstrated equivalent or superior health outcomes for vegan dogs. Brown et al (2009; n = 12) studied clinical examination and haematology data from dogs undergoing sustained, high exercise levels (sprint-racing Siberian huskies). The plant-based dogs appeared just as healthy as meat-based dogs, and no anaemia or other adverse effects were detected in the former.

Against the use of vegan or vegetarian diets is one study. Yamada et al (1987; n = 8) subjected dogs to four hours daily of enforced running at 12km/h for two weeks, following six weeks of rest. The plant-based dogs had lower circulating free cholesterol and suffered anaemia.

As I noted previously (Knight 2022), “virtually all studies can be critiqued, and these are no exception. In the oldest aforementioned studies, for example, sample sizes were small, limiting statistical reliability. However, in veterinary practice, certainty is often lacking and we are obliged to deal with probabilities when making diagnoses or recommending interventions most likely to benefit patients. In this case, the weight-of-evidence assessment is currently quite clear: nutritionally sound vegan diets produce health outcomes at least as good as – and in some respects better than – those produced by conventional meat-based diets. This also makes good sense biologically, when vegan diets are formulated to be nutritionally complete and balanced, palatable and digestible – as modern commercial vegan diets generally are – and when they may contain less dietary hazards, such as animal-sourced allergens or excess calories.”

In light of this, I repeat my call for those opposed to these diets to adopt evidence-based positions on this issue, particularly as evidence now indicates nutritionally vegan diets may improve longevity, and may decrease rates of some common health disorders. This fast-growing sector is attracting increasing client interest, and veterinarians should try to ensure their dietary recommendations are evidence-based.

Further comment and information:

Veterinary Professor Andrew Knight MANZCVS, DipECAWBM (AWSEL), DipACAW, PhD, FRCVS, PFHEA
- Professor of Animal Welfare and Ethics, & Founding Director, Centre for Animal Welfare, University of Winchester
- European & RCVS Veterinary Specialist in Animal Welfare Science, Ethics and Law; American & New Zealand Veterinary Specialist in Animal Welfare
- Fellow, Royal College of Veterinary Surgeons, & Member, Australian and New Zealand College of Veterinary Scientists (Animal Welfare chapter)
- Principal Fellow, Advance HE

Faculty of Health and Wellbeing
University of Winchester, Sparkford Road, Winchester, SO22 4NR, UK
https://www.winchester.ac.uk/about-us/leadership-and-governance/staff-directory/staff-profiles/knight.php

References
Brown WY, Vanselow BA, Redman AJ and Pluske JR (2009). An experimental meat-free diet maintained haematological characteristics in sprint-racing sled dogs, British Journal of Nutrition 102(9), 1,318-1,323.
Davies M (2022). Reported health benefits of a vegan dog food – a Likert scale-type survey of 100 guardians. bioRxiv, https://www.biorxiv.org/content/10.1101/2022.05.30.493980v2 accessed 17 Jun. 2022.
Dodd S, et al. (2022), Owner perception of health of North American dogs fed meat- or plant-based diets. Research in Veterinary Science 149, 36-46. https://doi.org/10.1016/j.rvsc.2022.06.002, accessed 18 Jun. 2022.
Keimer LA (2019). Vegan Diet and its Effects on the Dog’s Health, master’s thesis, Lithuanian University of Health Sciences Veterinary Academy, https://bit.ly/3Lo0jPS, accessed 19 May 2022.
Knight A (2022). The weight-of-evidence position on vegan diets. Vet Times 52(21), 23.
Knight A, Huang E, Rai N and Brown H (2022). Vegan versus meat-based dog food: guardian-reported indicators of health, PLOS One 17(4): e0265662. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0265662, accessed 18 Jun. 2022.
Semp P-G (2014). Vegan Nutrition of Dogs and Cats, Master’s of Veterinary Medicine thesis, University of Veterinary Medicine Vienna, https://bit.ly/3sHVXNa, accessed 19 May 2022.
Shotton J (2022). Is it safe to feed my dog a plant-based diet? Hold the greens-only meals – why the jury is still out on vegan dog diets, https://bit.ly/3yKqyNR.
Yamada T, Tohori M, Ashida T, Kajiwara N, Yoshimura H (1987). Comparison of effects of vegetable protein diet and animal protein diet on the initiation of anemia during vigorous physical training (sports anemia) in dogs and rats, Journal of Nutritional Science and Vitaminology 33(2), 129-149.