
Your cat
likely avoids using the leg to avoid pain. You may not be able to
determine the cause and severity of the pain, but your veterinarian
can. It may be a simple sprain that will go away on it's own, or it
can be an abscess, a thorn, arthritis or one of many other possible
causes. Arthritis usually starts subtly and increases gradually.
Abscesses, fractures, thorns and sprains occur suddenly. Since it could
be something needing medical attention, I recommend taking your cat to
the doctor immediately. If it is much better is less than 24 hours,
then you may be OK just waiting and watching.