When my six-month-old puppy was diagnosed with a congenital liver shunt, the vet placed him on a diet featuring predominantly dairy and plant-based protein.
Because my fur baby’s liver fails to filter out toxins in the blood as it should, a low protein diet based around dairy, fruit and vegetables reduces the volume of bacteria circulating in his system and helps to limit the ammonium urate stones he’s prone to.
Yet as we threw out the canned venison, beef bully sticks and goat horns, and stocked up on tofu, cottage cheese, ricotta, eggs, and other non-meat proteins, I felt a twinge of guilt.
These might be doctor’s orders, but could any meat-free canine truly be living his best life?
Feeding frenzy
Globally, the pet food industry is a big and growing business.
In 2022, there were 28.7 million pets in Australia, with dogs being the most common (48%), followed by cats (33%), according to Animal Medicines Australia.
Together they chow down $31 billion in food each year, IBISWorld figures reveal, with the market size of the local pet food production industry growing 1.2% per year on average between 2017 and 2022.
Mordor Intelligence data suggests that one of the factors behind this include the growing trend of pet humanisation, where we treat our pets like precious children, and open our wallets accordingly.
Increasing expenditure on pets is encouraging more new players to enter the market.
Some new products have emerged in response to pet owners questioning the health benefits of standard supermarket pet foods, preferencing premium, paleo-style diets.
For example, Raw & Fresh claims its Biologically Appropriate Raw Feeding (BARF) for pets, which includes high-quality meats, bones and organs, without fillers or additives like grain or preservatives, “mirrors the natural diet of wild ancestors, ensuring optimal health for pets”.
Reflecting what’s happening in the human world, there’s an equally vigorous swing towards veganism, vegetarianism and flexitarianism for pets.
For instance, Rascals Treats produces vegan treats, meal toppers and chewy sticks using ingredients not typically associated with dog food – like chickpeas, lentils, turmeric, chia seeds and spirulina.
And while this is in no way a sponsored post, my puppy thinks their Pump It Up! Pumpkin Dog Treats are the bomb.
Emerging research
Research just published in PLOS One claims that cats and dogs on vegan diets – which are even more restrictive than the one my puppy is on – not only survive, but thrive.
In the paper, published in October, Professor Andrew Knight of Queensland’s Griffith University writes that these pets “can have longevity and health at least equivalent, and in some respects superior, to those maintained on conventional meat-based diets”.
There are also additional gains for the environment when pets go vegan, Knight claims.
Knight’s analysis estimated a variety of potential benefits for environmental sustainability—including reduced freshwater consumption and greenhouse gas emissions—that could result from switching all pet dogs and cats in the US or around the world to nutritionally sound, vegan diets.
He pointed out that while many prior studies have focussed on livestock impacts in relation to human diets, few have considered the relative role of cat and dog diets.
To better understand these potential benefits, Knight calculated a series of estimates of the potential impacts of a hypothetical scenario in which all cats and dogs in the US or around the world were switched to nutritious vegan diets.
Research claims that cats and dogs on vegan diets not only survive, but thrive.
He used pet population data from 2020 for the US and 2018 data for the worldwide estimates.
Other inputs came from a variety of prior studies and governmental databases.
The estimates suggest that the amount of livestock consumed by dogs and cats in the US may be about one fifth of that consumed by humans, and about one tenth globally.
If all US dogs and cats switched to vegan diets, the model estimates, nearly two billion land-based livestock animals might be spared from slaughter yearly – and nearly seven billion if all cats and dogs around the world switched.
Billions of aquatic animals would also be spared.
The estimates also suggested significant potential reductions in land and water use, greenhouse gas emissions, use of biocides, and emissions of other pollutants.
For instance, switching all dogs worldwide to vegan diets could free up an area of land larger than Saudi Arabia, and for cats, larger than Germany.
Switching all dogs’ diets could result in an estimated reduction of greenhouse gas emissions greater than the amount of all emissions from the UK, and for cats, Israel.
Notes of caution
However, the Australian Veterinary Association warns that making a meat-free choice for your pet can be dangerous, and may put them at risk of disease, or even early death.
While acknowledging the impact different dietary choices can have on the environment, its president Dr Diana Barker points out that the teeth and guts of cats and dogs have developed to best suit a meat-based diet.
The estimates suggest that the amount of livestock consumed by dogs and cats in the US may be about one fifth of that consumed by humans, and about one tenth globally.
Dogs are adapted to a more omnivorous diet including meat and plants, but cats, she notes, are obligate carnivores, which means that they require meat to survive.
Meat provides cats with several essential dietary substances including the amino acids taurine and arginine, the fatty acid arachidonic acid, and vitamins A and B.
“Cats can’t make taurine – the only way they can get it is in animal products,” says Barker.
A pre-formulated, nutritionally balanced vegan diet for cats has not yet been developed, so ensuring meat-free felines are getting everything they need is well beyond the ability of most pet owners.
“It can be done but it’s quite complicated and requires a very dedicated owner,” she adds.
Barker also referred to another of Knight’s earlier papers, published in September in PLOS One, which purported to find better health outcomes for vegan cats as compared with meat-eaters.
Knight and colleagues analysed survey responses from 1,369 cat owners who were asked to report about a single cat in their household consuming either a meat-based (91%) or vegan (9%) diet.
After statistically accounting for other factors that could influence health—such as a cat’s age or whether it is neutered—the researchers found that participants reported that vegan diets were associated with a lower risk of several health indicators, although none of the differences were statistically significant.
Barker points out that this study was based on pet owners’ reports of what their animals were eating, with no independent verification of either their diet or their health status.
“We don’t know if the (vegan) cats were going out and getting their meat elsewhere … as in catching mice,” Barker says.
She also noted that vitamin deficiencies may not reveal themselves for many years – with cats deficient in taurine and other essential amino and fatty acids typically presenting with lethargy, neurological problems and anorexia.
Barker said there was a bit more leeway with dogs, some of which may remain healthy on vegan or vegetarian diets.
Dogs which were allergic to animal proteins, or had other types of health problems, could be prescribed a meat-free diet.
But it was vitally important to gain dietary input and advice from a veterinarian, to discuss the dog’s needs and to develop a diet plan that minimises health risks.
“The important message is, ‘Don’t wing it,’” she says.
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