RAYMOND Calvert looks into the valley, palls of smoke rising from animal pyres. The dark clouds which hang above the burning carcasses of slaughtered beasts are an even darker omen for him and his family.

An invisible county boundary separates his Yorkshire Dales farm from blighted Cumbria, but he knows this is no protection from the plague which is ravaging livestock there.

"We are ten miles from the Cumbria m boundary, behind that I can see fires burning," he says. "It looks damn near and it's a hell of a sight."

Not a minute goes by when Mr Calvert is free from worry. "I dread opening the door," he says. You go out in the morning and check your stock for signs. You can't get it out of your mind. You go to bed and it's there, you wake up in the morning and it's still there. It's just a complete nightmare. Every day my brother and I plot the new outbreaks on a map."

He has everything to lose - his stock, his farm, his way of life. "I honestly don't know what I would do. I'm totally dependant on Swaledales. It would totally destroy me, I know it would."

As an upland farmer, Mr Calvert, the secretary of the Tan Hill Swaledale Sheep Show, is made of stern stuff. He's had many a knock before and survived, but the latest crisis is the worst he has ever known and he says the country doesn't realise what's at stake.

To the outsider, life in the upper dales seems hard and thankless, hard-up farmers picking over the meagre offerings that the inhospitable terrain begrudgingly gives up.

If the layman were to rank these hill men among farmers, they would undoubtedly fall far behind those who reap the riches of lowland areas, where lush fields once abounded with huge flocks of fat lambs.

The reality couldn't be further from the truth. The three-tier system of sheep farming begins in the uplands and is dependant on the farmers who pride themselves on their pedigree breeds. The aim is to breed a prize tup, or ram.

"It's primarily about breeding stock, which is a lot more interesting than just breeding for sheer weight," says Mr Calvert. "You always have the ideal type of sheep in mind and you try to breed as closely to that as possible. But it isn't easy. There are many disappointments and it takes meticulous breeding. One bad tup can put you back years. So you are always hoping to at least maintain what you have got and hopefully improve on it."

The Swaledale is the ideal sheep and the mainstay of farming in upland areas. Hardy and prolific, they can survive in poor climate on meagre vegetation. They live happily on the fell during hard winters, lamb in the spring and then return to the tops. But they are as susceptible to foot-and-mouth as any breed. "The Swaledale sheep makes it possible to make a living in places like Swaledale, where it would be hard to make a living from such poor land," says Mr Calvert, of Hoggarth's Farm, Keld. "No Swaledale sheep in Swaledale would be the death of the dale."

Upland farmers ensure Swaledales are kept pure for breeding. Ewes are mated with a Swaledale ram and, after producing three crops of lambs, are sold off. Three quarters of the lambs are kept for breeding, the rest are sold to farmers who own marginal land, between the hills and the lowland. These sheep are mated with other breeds, such as the blue-faced Leicester, to produce grey-faced mule gimmers, which combine the best characteristics of each breed.

The third tier involves selling these mule ewes to lowland farmers who breed them with meat rams, Suffolks or Texels. Their offspring are the true fat lambs, sold for their meat.

Pivotal to the industry is the sheep show. It's where breeders meet for the first time after months of winter isolation. It's where they show off their prize stock. It's where they improve their flocks by spotting the good stock. It's also where they battle it out for honours. Foot-and-mouth has put paid to that.

"I have always had one ambition in life, since leaving school, and that was to produce a champion Swaledale," says Mr Calvert, eyes glinting. "Then last year, with my brother, I was fortunate enough to have supreme champion at Hawes. That was a dream come true, winning one of these fine rosettes given by the Swaledale Sheep Breeding Association. It's on the mantlepiece and that is where it's going to stay."

It's a serious business and not simply for the kudos involved. Having a supreme champion means big money. An average tup can fetch a few hundred pounds. If it wins a prize, that value can rocket to £10,000. The breed record was set in 1997 when a tup from Hawes was bought by a syndicate for £50,000. But, prize sheep or not, the death sentence awaits if the virus strikes.

The premier gathering in the dales is the Tan Hill Swaledale Sheep Show, which should have celebrated its 50th anniversary on May 31 but, for the first time in its history, it's expected to be cancelled. A final decision is still to be made.

Foot-and-mouth has the power to lay waste to whole breeds, both common and rare. If it continues, protected species could be made extinct, ending years of work by the Rare Breeds Survival Trust. "No rare breed has become extinct since we were formed in 1973," says trust member Dennis Vernon. "But this is a big, big threat."

Volunteers have worked tirelessly for decades to prevent the disappearance of individual native breeds, whether they are sheep, cattle, horses, goats or pigs. They have monitored population and blood lines, encouraged pedigree registration and a variety of breeding programmes through the bull and boar semen banks, embryo transfers and by the importation of bloodlines of selected breeds. Semen stores will ensure the survival of rare cattle, but there's no such fall back with sheep.

In the highest reaches of the Lake District the Herdwick thrives. But it's the only place on the planet the sheep exists. Legend has it they escaped from Spanish galleons wrecked during the Armada invasion in 1588 and have been known to survive in snow by eating their own fleeces. Famed for coarse wool and strong meat, they are irreplaceable. "It's an exceptional breed and I dread to think what would happen if foot-and-mouth spreads up there," says Mr Vernon.

The white, wild Chillingham cattle once only lived in Northumberland. But after nearly being wiped out by the previous foot-and-mouth outbreak in 1967, a second herd was formed elsewhere in the country.

"It's tragic," says Mr Vernon. "No amount of compensation can replace 20 years of breeding."

Spokesman for the Masham Sheep Breeders' Association, Frank Pedley, fears for the future of rare flocks in Wensleydale. "We are just crossing our fingers but it's so close now," he says. He describes the 1,300-strong stock, with a bloodline stretching back 125 years as "a rare and unique breed". "It has the finest lustre wool in the world. And it has the highest genetic resistance to scrapie - ironic since it has no special protection against foot-and-mouth."

Without animals to graze, the shape of the countryside will change forever and, with no end in sight to the crisis, that stark reality moves ever closer. Already, the rural scene is moving beyond recognition - an empty land devoid of colour and life with footpaths blocked and "keep out" signs posted everywhere. Take a deep breath for that lung-full of fresh country air and all you will get now is the acrid stench of disinfectant and smoke.