I first want to start off by say how important it is to cut your guinea pigs nails. It should be done at least every 30 days once a guinea pig reaches 2 months of age and up.
Why should it be done at all? Well just like cats and dogs, guinea pig nails can and will grow to the point of either curling into their feet or catch and rip off. If the nail rips off your guinea pig could bleed badly, even to the point of death if it doesn't stop
If you get a guinea pig at a rescue or through an ad and the guinea pig has over grown nails, it has been suggest that you clip the nail, a little at a time every week to few weeks. This will push back the quick. Also you may talk to you vet about coming in and getting it done by them the first time.
But whats a quick? In light colored nails you can see the quick, it is the pink area before the tip of the nail. This is the blood supply to the nail, and you do not want to cut this. But if you do, as it does happen, put the nail in styptic powder (you can find this at more pet supply stores or even dog groomers). This will usually stop the bleeding.
Here is a photo step by step on how Cutemomome cuts Emma McChompChomp nails.
Emma getting ready for her nail trim.
This is how Momo holds Emma.
"I always trim the *front paws* first, this way, when they kick and fuss, it would be less like to be scratched by just-clipped nails" - Cutemomome
Momo rest their back paws on a flat surface to trim the nails. You can see the quick (pink area). Remember to try not to cut this only the tip area that is not pink like the quick.
~Shinning a flash light under the nail to see the quick is very helpful on dark nails, those this may not work for black nails.~
This is a skinny pigs nails.
Please note, Skinny pigs not only need to have their nails clipped but they also need them filed smooth. Here are 4 sets of before and after shots.
Here is a GREAT Video found on Youtube. It has helped us when we started cutting for the first time.