Tributes flow in to the British soldier who worked with his dog to defuse bombs in Afghanistan

Colleagues said army dog handler Liam Tasker was inseparable from his spaniel, Theo, and so it was to the end. When Lance Corporal Tasker was shot dead in southern Afghanistan, his dog survived the shooting only to suffer a fatal heart attack when it returned to the British base at Camp Bastion.

Tasker, 26, was on patrol north of Nahr-e-Saraj in Helmand province on Tuesday with the spaniel, which was trained to search for arms and explosives, when they were caught in gunfire. He died from his injuries.

He was described as having a "natural empathy with dogs". His successful operations "undoubtedly saved many lives", the Ministry of Defence said. The army has about 400 dogs trained to sniff out explosives and weapons but the ministry declined to say how many were deployed in Afghanistan.

Born in Kirkcaldy, Fife, Tasker joined the Royal Army Veterinary Corps after starting his career as a vehicle mechanic. A member of 1st Military Working Dog Regiment, he was attached to 1st Battalion Irish Guards in Afghanistan.

Major Alexander Turner, officer commanding 2 Company, 1st Battalion Irish Guards, said: "He used to joke that Theo was impossible to restrain but I would say the same about Lance Corporal Tasker. At the most hazardous phase of an advance, he would be at the point of the spear, badgering to get even further forward and work his dog. He met his fate in just such a situation – leading the way that we might be safe."

His girlfriend, Leah Walters, said: "LT never met anyone without touching their lives in some way. The amount of support both I and his family have received in the last day alone pays testament to this."

His family said: "He died a hero doing a job he was immensely passionate about. We are so proud of him and everything he's achieved."

Among many tributes, Liam Fox, the defence secretary, said: "From the accounts made by his military colleagues and his family, I understand that he was a dedicated and highly capable soldier, whose skills in handling dogs were second to none. He and his dog Theo had saved lives and for this, we will be eternally grateful."

A total of 358 UK military personnel have died in Afghanistan since 2001.