The stag hound packs which chase red deer in the West Country, on Exmoor and the Quantock Hills, can no longer deny their sport is cruel, said Professor Patrick Bateson, a Cambridge University animal behaviour expert.
His report, published yesterday, concludes that shooting by stalkers is a much more humane way of controlling deer numbers. It was commissioned by the National Trust, whose ruling council is today expected to ban stag-hunting on its land at a special meeting.
The trust's council is also expected to call on the Government to commission a study into the stress which hunting with hounds causes to foxes - and whether this can now be justified as a way of controlling their numbers. The report could not come at a better time for Labour. Unlike the Conservatives, the party is against hunting with hounds. Its manifesto promises a free vote in Parliament on legislation to outlaw it.
Evolution has left the red deer pitifully unequipped for pursuit by hunters on horseback with dogs. Being ''relatively sedentary'' they lack the musculature and stamina for the long moorland chases which last on average three hours and cover 12 miles but can range for more than 20. Their natural predator is the wolf and wolf pursuits are much shorter than human ones, the report says.
The evidence of prolonged, acute suffering comes from measuring levels of biochemicals related to exhaustion, stress, pain and cell damage in blood taken from 61 deer immediately after they were held at bay by the hounds then dispatched with a gunshot. Concentrations were compared with those in deer at rest, those critically injured in road accidents and those shot by stalkers. Professor Bateson said: "It's clear these [hunted] animals are completely depleted of resources - they are desperately affected by long chases. From the point of view of physiology, the results are absolutely unambiguous.''
He and Elizabeth Bradshaw, an Oxford University biologist, found pursuit caused the deer's red blood cells to break up. Their damaged muscles leaked chemicals into the bloodstream.
A long chase left their blood plasma, normally clear, tinged magenta red with freed haemoglobin. Blood levels of cortisol, a stress hormone which speeds up heart rate and releases sugar into the blood, leapt at the start of the hunt and rose as it proceeded. So did levels of beta endorphin, a natural chemical similar to morphine involved in pain-control.
The report says deer which escaped the hounds - about half - suffer severe stress, take days to recover and would probably be left more vulnerable to infection and disease.