A campaign has been launched to tackle the devastating impact of a "hidden menace" on livestock.
The National Farmers' Union Mutual has backed the initiative to raise awareness and alleviate the number of lambs being attacked by domestic dogs.
Farmer Graham Palmer, from Lambs Park, Sheepstor, on Dartmoor, is one of many farmers and landowners who are concerned about dog attacks in the countryside. He has lost hundreds of hours' work and thousands of pounds in damages to dog attacks and sheep worrying over a period of 25 years.
He said: "It has been an absolute nightmare. I once ended up in hospital due to sleep deprivation from stress.
"One of the my lambs was left to die after having its face ripped off by a dog. It managed to survive several days, but eventually had to be put down.
"Owners often don't realise their animals are capable of carrying out such horrendous attacks. But when they get a blood lust, it can cause great distress both to the livestock and to the farmer."
The programme will involve puppies being introduced to farm livestock and horses at an early age, in a bid to reduce their fear and aggression towards livestock they meet in the countryside.
Nicki Whittaker, an equine specialist at NFU Mutual, said: "Most dog owners are very responsible and keep their animal on a lead around horses and livestock. However, some dogs may never have encountered sheep or horses before and may chase or attack them, resulting in death or injury."
Ms Whittaker added: "The countryside is a wonderful environment in which to walk your dog, but it's important to remember that it's a shared space and everyone has to play their part to ensure that it remains a safe and enjoyable place for people to live, work and enjoy their leisure pursuits."
A recent Environment, Food and Rural Affairs Committee report into dog control and welfare advised the police to show more consistency in prosecuting owners of dogs that attack livestock and horses.
In 2011 there were almost 700 cases of sheep worrying in the UK, which NFU Mutual estimates cost the industry around £1 million.
Tim Price, a rural affairs specialist at NFU Mutual, said: "Add to this the number of injuries to horses attacked or frightened by dogs and subsequent injuries to riders who have been thrown from their horses and the scale of the problem in the countryside becomes clear."
The campaign comes as the British Horse Society claims the number of horses being attacked by dogs nationally is also growing at an alarming rate. More than 400 incidents on horses have been recorded according to the society's accident website launched in November 2011.
Sheila Hardy, senior executive in the safety department at the British Horse Society, said: "Dog attacks on horses are the fastest-growing category of incidents being reported through our horse accidents website and the most common after road accidents.
"This is a worrying trend and we urgently need to educate both dog and horse owners about the problem.
"The consequences of these incidents can be particularly nasty with serious injuries being caused to both riders and horses. Dogs can also be injured and even killed," she added.