This was a fictional story about 2 men travelling through the desert with a herd of sheep.
I remember one of the men was much older and wiser. He knew how to survive in the desert. He explains at one point the best way to drink water to minimize thirst is by only drinking a couple mouthfulls at a time and holding the water in your mouth for a while before swallowing. Also, I remember a scene where the old man uses tobacco smoke and blows it onto the sheep to get rid of ticks. Possibly took place in North America, maybe around Utah. I read it in middle school no later than 2004 but it might've been published decades earlier.