Few things are as important to the wellbeing of our dogs and cats as their diets…

Nutritional needs differ when animals are very young, very old, pregnant, lactating, exercising a lot or a little. Overnutrition may result in obesity and a range of adverse consequences such as diabetes, arthritis and fatty tumours. Alternatively, undernutrition may result in progressive loss of bodyweight and increased susceptibility to a range of diseases. Nutritional deficiencies can also result from inappropriate diets.

And our dogs and cats are far from the only animals affected by the dietary choices we make for them. Globally, some 70 billion terrestrial animals are now slaughtered annually. This exceeds the entire human population, by an order of magnitude. Most of these animals suffer significantly during their unnaturally shortened lives. Modern high density, high throughput, and highly artificial systems, along with genetic selection for maximal productivity, and invasive husbandry procedures, have led to a range of serious animal welfare concerns in all major farmed animal species. One to three trillion fish are also killed annually, many of whom are now farmed in intensive fish farms. Wild caught fish usually experience severe trauma at the times of their deaths.

Increasing concerns about the animal welfare and environmental impacts of animal farming and fishing have led many people to explore non-animal diets for themselves, and for their companion animals. These are formulated from plant, mineral and synthetic ingredients. But, how safe could such diets be? Cats and dogs are carnivores, right? Not quite. Dogs may be biologically classified as omnivores, due to their ability to subsist on a mixed diet of animal and plant-based material in their natural environments. For thousands of years they co-evolved with humans, scavenging both plant- and animal-based food scraps around our  campfires. In contrast, cats remain obligate carnivores, because of their evolutionary natomical, physiological and biochemical adaptations to a hunting lifestyle. Both wild cats and dogs consume plant material naturally, primarily sourced from the gastrointestinal tracts of their consumed prey.

But doesn’t meat allow greater fulfilment of natural feeding behaviour? Once again, this claim warrants closer scrutiny. When wild cats or dogs kill prey, they gorge as much as possible to prevent consumption by competitors. This is followed by uncertain periods of hunger. Yet, commercial meatbased diets comprise assorted body parts from animals such as cows, pigs, sheep, ducks, chickens and fish – animals that cats and dogs never naturally eat – heavily laced with unnatural additives of questionable safety (Knight and Leitsberger 2016). These are dispensed from tins or packets at predictable times daily, with kibble sometimes available around the clock. The result bears very little resemblance to natural feeding behaviour.

As their guardians, we frequently microchip, vaccinate, de-worm, de-flea and de-sex our furry companions, and confine them indoors at night, because we correctly understand that such unnatural steps are necessary to safeguard health. Why then, do we so often resist feeding healthy vegan diets to cats and dogs, on the basis that it is ‘unnatural’? After all, cats, dogs and indeed all species, have requirements for specific dietary nutrients, not ingredients. There is no scientific reason why a diet comprised entirely of non-animal ingredients cannot be formulated to meet all of the palatability, nutritional and bioavailability needs of the species for which they are intended. In fact, a growing number of commercially available vegan companion animal diets aim to do exactly this, and studies demonstrate that animals maintained on nutritionally sound vegan diets can be perfectly healthy (Knight and Leitsberger 2016).

If a diet is nutritionally inadequate – whether vegetarian or meat-based – disease is likely to result eventually. Hence use of a nutritionally complete and reasonably balanced commercial diet, or of a nutritional supplement added to a home-made diet, is essential. Both are available from suppliers listed at www.vegepets.info, and elsewhere.

Regular urine acidity monitoring is also important to detect urinary alkalinisation, with its consequent potential for urinary stones, blockages and infections, that may result from
a vegan diet, in a small minority of cases. Urinary alkalinisation may be corrected via a
range of dietary additives. Further information can be found at www.vegepets.info.

Additionally, some studies have indicated that neither meat-based nor vegan diets are always formulated consistently. Accordingly, guardians may wish to consider gradually transitioning their pets onto different brands or diets, every few months, in the hope that any deficiencies will at least differ between different diets.

As with all companion animals, guardians should also monitor the health of their animals on a regular basis, including through regular checks of bodyweight, activity level and demeanour. Although checks should normally occur at least weekly, assessments should be conducted more often if required. Any problems, such as progressive weight loss or more obvious signs of illness such as adverse coat changes, vomiting or diarrhoea, should trigger a veterinary examination; which should, in any event, occur at least annually. Owners should consider routine blood screenings and urine tests during such wellness checks, and in the case of illness (Knight and Leitsberger 2016).

Great patience and persistence may be required when transitioning animals onto new diets. Changes are best made gradually, e.g., by feeding a 90%/10% old/new dietary mixture for a  few days, then 80%/20%, and so on. This allows an appropriate transition of digestive enzymes and intestinal microorganisms, minimising adverse reactions such as abdominal discomfort, flatulence and diarrhoea (Knight and Leitsberger 2016).

Guardians should clearly demonstrate that they consider the new diet just as edible as the old (without possibly warning or alarming their pet by making a fuss). They should not be concerned if animals eat around new food at first. Simply having it in close proximity will help create the necessary mental association, as will mixing the food thoroughly. The addition of odiferous (the sense of smell is very important) and tasty additives, such as nutritional yeast, vegetable oil, nori flakes and spirulina, can all help, as well as gently warming the food. Offered food should always be fresh. Gradual change and persistence are the most important factors for transitioning resistant animals and using tactics such as these, the most stubborn of animals have been successfully transitioned onto vegan diets (Knight and Leitsberger 2016).

Such diets have reportedly been associated with a range of benefits, such as improved coat condition, allergy control, weight control, increased overall health and vitality, arthritis regression, diabetes regression, cataract resolution, and decreased incidences of cancer, infections, hypothyroidism and ectoparasites (fleas, ticks, lice and mites). Few controlled population studies exist, although those published to date confirm the potential for cats and dogs to be healthy and active on nutritionally sound vegetarian and vegan diets (Knight and Leitsberger 2016).

Acknowledgement: Some parts of this article have been excerpted with permission from a similar article by the author in New Zealand Green for Life, Winter 2018, p. 16. Reference: Knight A and Leitsberger M. (2016). Vegetarian versus meat-based diets for companion animals. Animals, 6(9), 57. www.mdpi.com/2076-2615/6/9/57.