The most common mobility challenges facing senior dogs are joint pain, muscle loss, or a general loss of energy, which can be caused by physical aches and pains and a mental gap. Steoarthritis is the most common cause of limited movement in senior dogs, leading to inflammation and bone-on-bone wear during movement, which causes them to feel stiff and uncomfortable. As dogs age, their bodies become less efficient at maintaining muscle mass, especially in the hindquarters, which leads to a decrease in muscle mass. The solution is to maintain muscle through gentle, consistent, age-appropriate movement. PetGuide may receive a small affiliate commission from purchases made via links in this article, but at no cost to you.