Captain Seiryo Yamashita,Veterinary Department,15 Division quoted in Tales by Japanese Soldiers,John Nunneley and Kazuo Tamayama...12,000 horses,including mules,30,000 oxen and 1,030 elephants were used by the 15th Army..all the horses died in the mountains but several mules that survived arrived back at the river.Japanese horses died earlier than mules.The average time that Japanese horses survived..was 55 days against 73 days for mules.It was remarkable that almost all of the elephants were able to survive despite hard work in such difficult jungles and they returned to Burma..
Supporting evidence of the Japanese death toll in Burma,page 252:
Out of 305,501 Japanese officers and other ranks that fought in Burma,185,149 men were killed or died of sickness and only 39 per cent(118,352 men) were able to reurn to their homes..