The guinea pig must be comfortable, and can either be standing in front of you or held in your arms (gently but firmly).
The consistency of the feed needs to be that of “gloop” and not too thin or thick. He can only take up to 0.3mls of supplementary feed at a time. This can be done up to six times per day and should not be rushed.
Cut off the tiny mouth end of the syringe so you can suck up the gloop mixture into the now-wider barrel of the syring for feeding. Do not lose the little black stopper down his throat.