The ark of Yahweh was in the country of the Philistines seven months.
"Milch" cows (1 Samuel 6:7; 1 Samuel 6:10) are cows that are still nursing their calves. It would be very unusual for nursing cows to leave their young and head for a town some 10 miles away. Indeed the Philistines regarded this behavior as miraculous and indicative that Yahweh had been punishing them.