They deserve their medals: the war messenger pigeon that survived three near-death attacks; the cat that escaped a mortar shell to become champion rat catcher on a navy ship under siege; and the Labrador that gave a paralysed Gulf War veteran his life back.

Now, for the first time, a new exhibition at London's Imperial War Museum explores the remarkable role of animals in conflict. And it includes much more than the expected dogs and horses...

Nowadays pigs and rats are used to sniff out landmines, as they have a better sense of smell than dogs and are up to a fifth cheaper to train. The US Navy uses bottlenose dolphins and sea lions to locate underwater mines and other sub surface threats.

It is estimated more than 16 million animals served in the First Wold War. By 1918, the British army were using over 800,000 horses, mules, camels, donkeys and oxen. Nearly 500,000 pack animals died in the war. Today the army has only one mule, Alfie, on its strength.

500,000 war messenger pigeons

Over 500,000 pigeons carried messages in the Second World War, about 20,000 of which were killed in action. Mary of Exeter, one of the bravest, survived a partly shot-off wing, a savage attack by a hawk and a neck wound so severe that she had to wear a collar to support her head. Nevertheless she completed five years of service for Britain, earning a PDSA Dickin medal - the Victoria Cross for animals.

Simon, a black-and-white cat, was awarded the same honour for single-pawedly saving the food on the HMS Amethyst from a rat plague while the ship was trapped on the Yangste River in China in 1949. Despite being wounded by a mortar shell, he caught at least 18 rats during the 100-day siege. "He was a very determined little cat," recalls lieutenant commander Keir Stewart Hett, 79, who was made "cat officer" to handle Simon's mound of fan-mail after the ship's escape.

Another young hero featured in the exhibition is the cocker spaniel Jake, who saved the lives of several badly wounded victims on the bombed bus in Tavistock Square on July 7 last year. Just two months after his police training, the little dog and his handler, PC Robert Crawford, cleared a way through the wreckage for explosives officers to reach a suspected second bomb - a microwave box on the parcel rack behind the driver. Once it was made safe, paramedics could treat the injured. "It was quite horrific," remembers PC Crawford. "But Jake seemed to take it in his stride."

'I have my life back, because of a dog'

The four-footed heroics also continue post-war. In 1991, after 20 years in the Royal Navy, chief petty officer Allen Parton suffered severe head trauma in a road accident during the Gulf War. He was a "blob in a wheel chair" who could not speak, write or walk, Parton recalls. The once happily married man had lost his ability to love, laugh or cry, along with the memories of his wedding to nurse Sandra or the birth of their two young children, Liam and Zoe. "We sort of plodded on as a family, but I didn't love them. I was a completely different person."

Then, nine years ago, Parton accompanied his wife to a class where she served as puppy walker for Canine Partners - a charity training dogs to help disabled people. Endal, a little yellow Labrador with a health- and attitude problem, instinctively started piling objects into Parton's lap, eliciting his first smile in half a decade. "It seems two crocks together made a dream team," Parton says.

Endal understands over 1,000 commands in sign language. "Though I couldn't talk to humans, I could communicate with a dog. He also gave me back the emotions I have lost." The dog can even operate a chip-and-pin machine, load the washing machine and lift the toilet seat for Parton. ("Being a man-dog, he won't put it down.") The Labrador was Parton's best man when he re-married Sandra in 2002. The Partons' marriage was one of just five in 85 that survived the husband being injured in the Gulf War.

"I was a serviceman who had lost the will to live," Parton says. "I've had two attempts at suicide. I had lost my past, i had lost my future. Now I'm back with my wife and children because of a dog."

In 2001, Endal saved Parton's life when a speeding car knocked him out of his wheelchair. He put him in the recovery position, covered him with a blanket, fetched his mobile phone and sought help. For that, the dog was awarded the PDSA gold medal for peacetime bravery.

Goats, ferrets, and war cries

The Shetland pony Cruachan III, named after an ancient Scottish war cry, is the proud owner of four medals - but for entirely different reasons. As the mascot of the Argyle and Sutherland Highlanders, the beast has been decorated for all the places where his regiment has served - including Northern Island, Iraq and Bosnia (although he has never set foot outside the UK).

The First Battalion Yorkshire Regiment keeps two ferrets as its unofficial mascots - lazy Imphal and lively Quebec, who once tried to escape the base via a drainpipe but was lured back with biscuits.

Shenkin II, a goat hand-picked from the Queen's herd to serve as mascot for the Third Royal Welsh Regiment, leads an even cushier life with his own sponsored Land Rover and trailer. "He can say hello," boasts his handler, sergeant David Joseph. And indeed, when he pulls at the goat's lower lip, it utters a sound remarkably like a greeting.

These are the few lucky ones. But there are also the many that suffer. Like the 400,000 cats and dogs put down in London at the start of the Second World War, the 14 million horses that perished on the Russian front, or the lion Marjan left to die toothless, lame and half-blind at Kabul's looted zoo four years ago.

In the words of Ingrid Newkirk, president of the People for the Ethical Treatement of Animals (PETA): "For animals, there is no Geneva Convention and no peace treaty - just our mercy."

  • The Animals' War, Imperial War Museum, London, until 22 April 2007. Admission fee. Enquiries: call 020 7416 5320/1, or visit www.iwm.org.uk/animals.