What is happening
"He can't get up the stairs anymore." "Her back legs are giving out." Mobility decline is the single most common, and most heartbreaking, reason owners come looking for help. Behind it is a slow erosion of cartilage, joint fluid and the soft tissue around the joint, often years in the making before you notice the first hesitation on the stairs.
Because animals mask discomfort by instinct, the early signs are quiet: a slower first few steps after sleep, a boost onto the couch that has become a scramble, a shortened walk, a new preference for the ramp. None of this is "just old age", it is the early, treatable stage of decline.
