An abscess can cause pain long before it comes up fully, as I know from my own piggies (any my own toothache). It is not at all easy to find or notice before blowing up.
If the abscess has developed a pouch, then it needs lancing and very thorough flushing by the vet. It also needs to have to be marsupialised (the exit stitched open) for twice daily flushing at home for as long as possible, ideally at least 5 days but the closer you can come to 10 days the better to allow any last bit of infection to come out. In the later days you may have to work off the scab that is forming in order to the get last bit of pus out that could cause the abscess to return.
Your vet will have to give you a syringe with needles so you can create enough pressure to get the mildly antiseptic mix in deep enough (saline solution, f10 or hibiscrub all work) by holding the needle into the opening and then pushing the fluid into the hole. An abscess needs to heal from the inside out.
It is not a pleasant job - except for when you are our Abscess Queen,
@furryfriends (TEAS) ! But it is necessary...
My dental abscess piggies have also been put on maximum dog metacam (0.25 ml twice daily for a ca. 1 kg piggy) and been prescribed a course of zithromax (azithromycin), which is the antibiotic most effective to cut through an abscess. The dosage is 0.1 ml per 100g of body weight. It is however not officially licensed for guinea pigs but I hope that your vet may be open-minded.
Your vet will also have to correct any teeth; he will find that one side is likely overgrown because of one-sided chewing.
The good news is that the pain from the abscess will stop instantly as soon as it is lanced.
Please make sure that you have probiotics and syringe feed at home in case your boy is not eating straight away or a strong antibiotic is impacting on the gut microbiome and killing off the appetite.
Good luck!
glad he is eating some hay though. We are still syringe feeding. Hopefully he comes around.
