With a low mist hanging over the backs of his cows like a white shroud, John Lewis-Stempel frets as his vet tests his treasured herd for dreaded bovine tuberculosis on a dark December morning.

I found the lump yesterday morning. She was leaning forward, taking a drink of water, and my hand was on her neck, caressing her. And there was the lump. It was dark, so I felt further down. Another lump.

It’s what every farmer fears, a cow reacting to the skin test for bovine tuberculosis (TB). Oh, the principle of the TB test is simple enough: each cow is injected in the neck by the vet in two places, first with an antigen from bovine TB, second with an antigen from avian TB. Said vet comes out to check for bumps 72 hours later. A ‘reactor’ cow, one carrying the disease, will come up in bumps, which is a death notice, delivered by a green tag punched in the ear.

Except the assessment of bumps is far from simple. It depends on how precisely big the bump is. Then, is the avian or the bovine one bigger? Some delicate, wilting-violet cows will bump to the steel needle, let alone its active contents.

The merest hint of a bump on a cow and I panic. Reason flies out of the window. I fluster. I can’t remember even whether the key skin prick, the bovine, is top or bottom. Every cow has worth, but, in a small herd of 10 like ours, every cow has meaning, plus, I confess, a name. In the case of our Red Polls, these by family law begin with M. (The book of baby names has been well plundered over the years. We’ve done the spectrum from the haughty Margot – think a cowy version of Penelope Keith in The Good Life – to the buxom Mirabelle, a natural to advertise butter.)

bovine tb

Milly is a particular favourite, with her fluttery eyelashes and pawky humour. A couple of years back, she kept escaping and I was utterly perplexed until I caught her red-hooved. Her modus operandi was to squiggle on her side under the single-strand electric fence. I wouldn’t want to lose her. Really, really wouldn’t.

I tell you now, the TB test is hell. I don’t sleep before it, don’t sleep during it. Today is D-Day: the day the vet comes back to check for bumps. I got the cattle penned for examination just after first light and getting the girls into the pen is sufficiently stressful for me to pop aspirins. (I read somewhere once that aspirin mitigates strokes. Or heart attacks. One or the other.) It’s stupid, but one does not want to be the cowman whose failure to pen cows is tittle-tatted by the vet down the line to the neighbours.

I took no chances. I led the girls into the pen with a shaken bucket of cattle cake, me running faster than anyone at Pamplona, because being caught up by five tons of milling beeves is interesting to say the least. The girls in the pen, I two-armed vaulted the side, nipped back around and closed the gate on them. Works every time, except the time I failed to clear the pen’s side, fabricated from motorway crash barriers, and broke three ribs.

A really great cowman, like our old neighbour Jack Williams over at Abbeydore, can pen cattle, even Limousins, by hypnotising magic. He sang them in.

It’s almost 10am now. The vet is due and I’m by the pen, paralysed with worry, mouth as sticky-parched as when you take a Communion wafer. The mist is low, axing off the top of trees beside the pen. There’s no compassion in a tree; on a day like this, their unthinking insensitivity and their self-regarding composure merely irritates. Somewhere off in the hedge, an unseen robin drips sad soliloquies. Lower still comes the mist to lie on the backs of the cows in white shrouds.

The tweed-jacket era of James Herriot is long since gone. Bob Minors looms towards me in green waterproofs, a doppelganger for an alien in Doctor Who of about 1980. ‘Any problems?’

I grimace, then push the internal gate behind the cows, so they’re pushed into the narrow metal-railed corridor of the ‘race’ (an odd noun for the place of the slow queuing of animals). To touch, the gate has condensed the chill of the centuries in its bars. Cows are hierarchical. Milly is mid-herd, number six. Bob leans over, runs his hands over the injection sites on the cows’ necks. He reaches Milly. ‘Ah,’ he says. And gets, from out of his tool box, the callipers.

He squeezes her warm vital skin and pinches it with the steel callipers. Once, twice, thrice, he measures the bumps on Milly’s neck.

Somewhere across the valley comes the coffin-closing croak of a raven. ‘Close, but good enough,’ says Bob. I don’t understand, comprehend, and ask him to repeat. ‘She passes.’

The world blurs. He runs his hands over the remainder. ‘They’re yours for another year. I’ll see myself off. You let them out.’

I famously only swear when I’m happy. ****! ****! ****! I release the cows from their confinement and me from my anxiety. We run around, the cows and I in the mist, laughing.

Twice crowned victor of the Wainwright Prize for nature writing, for ‘Where Poppies Blow’ (2017) and ‘Meadowland’ (2015), John Lewis-Stempel was the 2016 British Society of Magazine Editors Columnist of the Year