when cutting a bunny or guinea pigs claws, it is very easy to cut past the ‘quick’ by mistake, the quick being the point where the nail’s blood supply ends. Unless you cut well above the quick, it isn’t too serious, though very upsetting. even a little above the quick can really bleed.
as long as it stops within a few minutes, then there isn’t anything to worry about, though he might be a bit cross with you for a while. if you are concerned, make sure everything is clean, like litter trays, so he isn’t putting his claw into soiled litter for a while, give him lots of hugs, and try and let him know you are sorry!
Its good to get into the routine of taking just the tips off more frequently, as it reduces the likelihood of this happening. also use the press, press, click method, where you just press without cutting then cut on the third press down. this gives bunny or piggy time to let you know if you are over the quick!