I have 2 cats around the same age as each other, but sometimes their play gets a bit too rough, and my sisters cat (the elder one) will hurt the younger, and he will get cuts that bleed. Is my cat really hurting, or is it just a shallow cut, and what should i do about it.
Cats hide pain. It's instinctive. The cat that shows pain, in the wild, is the cat the predators attack first. Being that cat is not a good survival strategy. In fact, if a cat is showing outward signs of pain, it can be an indication it has given up, or that the pain is extremely serious- in either case, get to the vet.
If the cat is not showing pain, it is really hard to know whether it actually is feeling pain. Treat the wound like you would for a child that came in from playing in the yard crying because he fell and skinned his elbow. If the cat will let you, that is. Do your best to determine the severity by spreading the fur and seeing the length and depth of the cut. Apply direct pressure with a (non-adhesive) gauze pad until the bleeding is completely stopped.
As always, when in doubt- vet.