Trauma
Any wound, no matter how insignificant it may seem, should be treated as potentially serious. Even minor cuts and scratches can become infected or form abscesses; tiny puncture wounds may have resulted from bites or stings that introduce infection or venom. Clean minor wounds with mild soap and water, then swab them with an antiseptic solution. A bandage may be more trouble than it is worth for minor nicks. Have any unidentified bite or sting wound checked by a veterinarian.
Control heavy bleeding by applying pressure. When the bleeding has stopped, bandage the wound: Wrap the bandage around the wound and around the entire injured area of the body the whole tail or limb, or the entire torso or head. Do not bandage tightly. The idea is to secure the cloth without cutting off circulation. If there is a foreign object lodged in a wound, do not try to remove it; in fact, bandage around it without disturbing it at all. A tourniquet should only be used as a last resort if a limb or tail is too badly damaged for the bleeding to stop. Blood loss is a major cause of shock, so monitor breathing, pulse and general condition on the way to the vet.
A limp or swelling and signs of pain in a specific area may indicate a contusion (bruise), strain, sprain or fracture. Contusions and strains are rarely serious on their own, although if the pain continues for more than a few days, a trip to the vet is warranted. Sprains, the stretching or tearing of ligaments, and fractures, the cracking or breaking of bones, are more serious. Usually the ligaments or bones need to be set and immobilized in a splint or cast by your vet. It may be difficult for you to differentiate between the various possibilities, so it's better to be safe than sorry. After any kind of trauma, have a vet examine your cat for any associated internal injuries.
A dangling or twisted limb or a bone protruding out of the skin is a sign of a serious fracture. Be careful; fractures with jagged edges may cause further internal injuries. Get your cat to the veterinarian as quickly as possible, but attempt to limit his movement for the trip. You can immobilize him on a stretcher, which is particularly important if you suspect injury to the torso; or, place him in some kind of container. A cat carrier is the ideal receptacle (especially the type that opens from the top), but a cardboard box or laundry basket can also serve. But be careful when restraining your cat in either of these ways, mainly to avoid causing him pain, but also because an injured cat has a tendency to bite.
If an injured cat resists being placed on a stretcher or in any sort of carrier, simply wrap it loosely in a clean towel and transport it as is. Fighting attempted immobilization is likely to cause additional injury.