UPDATE 1-Caterpillar profit beats again as sales surge 35 pct

(Adds 2018 forecast, details) Jan 25 (Reuters) - Caterpillar Inc trounced forecasts for profit for the seventh straight quarter on Thursday as buoyant global demand and the recovery of commodities markets drove a 35 percent surge in sales of its construction and mining equipment. Shares in the world's largest heavy duty equipment maker were up another 2.7 percent in premarket trading and have now risen around 80 percent in the past year and 160 percent in the past two. The c