Called by parks to attend limping buffalo by Safari lodge. We located it and I darted it with 1cc M99. The buffalo went down 5 minutes later. He had a wire snare on his right hind hock. I decided this was a survivable wound and proceeded to clean and suture wound together. Buffaloes head was covered and his respirations were regular and not labored. After last suture the animal went into cardiac arrest within 20 seconds. Antidote was administered but the buffalo died. It was not anesthetic related as it was 40 minutes into episode and was wearing off. It was a very old Buffalo and due to its grey colour of its mucous membranes it indicated a stress induced heart attack. I was quite disappointed as it should have healed up. Mr. Khan and park team was on hand to assist me. My vehicle was severely damaged by driving thru the thick bush.