What it is
A healthy hip joint is like a ball resting firmly in a socket. With dysplasia the joint is loose and unstable, so with every step the bones rub against each other and the surface of the joint wears down.
The condition can be inherited. Signs may show in a young animal or only later in life, once the joint has worn.
Cats do not always show pain by limping. Their habits change instead: they stop jumping onto the windowsill or sofa, climb less, rest for longer. Changes like these are worth showing to a vet.
Signs you may notice
A cat stops jumping onto its favourite high spots, moves carefully, limps or walks with its back legs held low. Cats are good at hiding discomfort, so the changes can be subtle.
When to see a vet
Book a visit if your cat has started avoiding jumps, limps or moves differently from before.
This is general information, not veterinary advice. For your own cat's health, tests and treatment, see a vet.