During puppyhood you need to be alert for lameness, soreness in elbows, shoulders or hips. Because these large dogs grow so fast, they can get uneven growth or damage to the soft growing layer of bone in the joints. Too vigorous exercise with sudden stops and starts can cause this damage, so use care. Please avoid jumping out of vehicles, or even going down stairs quickly. These actions can overstress the joints, and may bruise or tear the soft growing layer of the bones, especially in the elbow and shoulder joints. Lameness or limping for no obvious reason (like he got his toes stepped on), indicates an immediate trip to the vet is in order.(This bone growth problem is also addressed by the dog food companies - hence the large breed formula to help regulate this growth.) Treatment can be conservative, restricting exersize, using an anti inflamatory drug and switching to adult food to slow the bone growth. Severe injury will usually require surgery, but start conservative at first. After 12 months or so this should no longer be an issue.