The Dog-shaped Incan Whistle is the 10th treasure in Uncharted 3: Drake's Deception.
The Dog-shaped Incan Whistle can be found in Chapter 3 - Second-Story Work. Get yourself to the roof of the L-shaped, covered porch that is outside the open window used to enter the museum. Before entering the window, turn left and head to the end of the roof. Climb down the yellow pipe in the corner and jump to the porch. The treasure is on the other side of the railing from the pipe.