You might think me eccentric for feeding my cat the highest-quality pet food, made with free-run chicken and turkey, freshwater fish and cage-free eggs. But I should not be considered the weird one. It is bizarre that in a supposedly animal-loving country, where half of all households have a pet, so many feed them on other animals that have lived miserable lives in factory farms. Walk down your supermarket pet food aisle and you’ll be hard pressed to find a single brand that claims to be made with high-welfare meat. More expensive pet food should not be about spoiling our cats but about sparing the farmed beasts we feed them.

This is just the most egregious example of what the Financial Times’s chief features writer, Henry Mance, describes as ‘the meat paradox’: a state of affairs where ‘people who care about animals manage not to care about farm animals’. It’s not just omnivores who are in denial. Vegetarians are arguably just as self-deceived. The life of a typical dairy cow is worse than that of one destined to end up as steaks. In the United States, up to half of dairy cows suffer lameness, a problem also rife in the United Kingdom. Vegetarians can’t even claim that at least they are not responsible for the slaughter of cows, since the economics of the dairy industry means that most male calves are killed at birth, once they have served their only purpose as catalysts of lactation. ‘If you are really concerned about animal welfare,’ says Mance, ‘you should almost certainly stop eating dairy before you stop eating beef.’

Mance’s catalogue of the horrors of industrial meat production represents a damning charge sheet, all the more so because this is not a new exposé but a compendium of facts that have been in the public arena for decades. Factory farming has been with us for about a hundred years, since Delaware chicken farmers worked out that they could keep their birds indoors their whole lives if they gave them vitamin D supplements. The attitude since has too often been the one expressed with shocking bluntness by the journal Hog Farm Management in 1976: ‘Forget the pig is an animal – treat him just like a machine in a factory.’

Mance’s polemic extends beyond the food industry. Zoos come in for a good kicking too, as he trashes their claims to have reinvented themselves as centres of conservation and research. One of his most interesting witnesses is Damian Aspinall, the son of the founder of two wildlife parks in Kent. Aspinall is slowly trying to close down the parks and safely free the remaining animals from captivity. He disputes the claim that zoos are havens for endangered species, saying that of the 850 or so mammal species held in European zoos, only forty-five are critically endangered. What’s more, most zoo mammals are not pure bred but have been hybridised through breeding with other species, so by the rules of conservation they could never be returned to the wild anyway.

So what is to be done? For Mance, the most effective and simplest step is to go vegan. He has little time for those who claim that ethical animal farming is possible. ‘Even good farms push animals’ bodies to the limit, while giving them little chance to flourish,’ he says, claiming that the idea we can eat only the best meat is ‘a mirage’.

He is surely right that the vast majority pay mere ‘lip service’ to humane farming. He cites a survey which shows that 75 per cent of American consumers say they buy ‘humane products’, in a country where only 1 per cent of livestock is raised on non-factory farms. The fact that most people do not live up to their aspirations is no evidence that such goals are unachievable, though. I have met many progressive livestock farmers who care for their animals in ways that might surprise even Mance. It is true, however, that even they cannot eliminate all suffering in their animals’ lives, and dairy herds still face the problem of male calf slaughter.

Mance acknowledges that ‘loving animals cannot mean imagining a fantasy land – without death, without suffering’ and rejects as ‘simplistic’ the idea that ‘it’s wrong to kill animals per se’. What really offends him is the ‘pointless lives’ of farm animals that exist only to provide us with food: ‘For humans, lives must have meaning. To watch animals accept their lives as machines would contradict that.’ But nature has no interest in giving its creatures meaningful lives. For most, it is a struggle for survival, where the pursuit of food and the production of offspring are the only goals. Salmon in Alaska returning to their spawning grounds are killed in their thousands by grizzly bears with no concern for their suffering. Wild ruminants live in fear of carnivorous predators who tear them apart alive.

One of the West’s earliest advocates of concern for animal welfare, Jeremy Bentham, thought that meat-eating was ethical because animals would suffer a worse fate in the wild. For sure, that is not true of the crated sow or caged chicken today. But the sheep and cows that graze the open fields of our best farms surely experience no worse lives than their cousins who take their chances with merciless predators, with no vets to help them when sick or to put them out of their misery if needed.

Mance’s self-professed realism is most evident in his acceptance of hunting as often justifiable, and he rightly laments the fact that more people get upset about it than they do about the miserable condition of factory-farmed animals. He also allows that eating molluscs is sustainable and cruelty-free. But his general zeal makes him too dismissive of arguments that compassion for and consumption of animals can go together.

It also leads him to make some flagrant mistakes, which the FT’s fact checkers would easily have spotted. His claim that there are 750,000 dog meat farms in South Korea confuses a high estimate of captive dogs with the number of farms that hold them. He also insists that ‘all animal foods are inefficient’ because ‘it requires twenty times more land to produce a gram of protein from cows and sheep than it does to produce it from pulses such as chickpeas and soybeans’. But he must know that much grazing land is not suitable for arable crops, and chickens and pigs can be fed on leftovers from arable farming that humans cannot consume. The most efficient food system would have much less animal farming than we currently have, but it would have significantly more than none.

Mance may overstate his case, but he is spot on to make us confront the horrible truth that the vast majority of us are supporting animal suffering every time we shop and only a tiny fraction of full-time vegans and conscientious omnivores are making serious efforts to change this. ‘What really threatens animals today is not cruelty, so much as thoughtlessness,’ he says. Mance’s book will force its readers to stop and think about the incomprehensible scale of unnecessary suffering we impose on our fellow creatures.