The anal glands on a glider are VERY delicate, and shouldn't be messed with, except to gently feel for swelling, and NEVER expressed, EXCEPT for what I will describe.
With Chronos, we thought he had a UTI (and he probably did for a long time-one of those 'he's always hissed when he peed, it's normal for him' comments from the former owner). We treated on/off for a year before we discovered what the problem was, and why, despite a number of different meds, it wouldn't leave. Within a week of going off meds, every time, he'd start hissing again...the last time before we found the abscess, he made the SM noise (but hadn't actually gone after himself with his teeth YET-just desperately licked the area).
When we took him back to the vet
yet again, the vet
gently felt around the glands, and noted that one was almost triple the size of the other-about the size of a pea (we hadn't thought to check them before). Several months earlier, we had cultured klebsiella pneumoniae in his urine (which the vet
said was unusual, but I didn't know why at the time, and took his word for it-I trust 2 of my 3 vets
without question). Well, his exploration actually caused what turned out to be an abscess to begin to drain a LOT...instead of milky white, a thick grayish green was coming out. Now the abscess was wide open and draining (and that was a good thing).
We covered all the bases with him, and put him on twice daily doses of Clindamycin, Metronidazole (Flagyl), and Baytril (enrofloxacin). BUT. Abscesses are a special case, and need to heal from the inside out, or you'll be right back at square one. In order to do that, it has to drain, and the pus/bacteria has to come out. We had to gently express the abscess daily while giving him his meds -there is NO way to get every single bacteria out this way-you have to try and get enough of the pus/bacteria out, that the antibiotics can begin to start healing the abscess, which should get smaller and smaller with time, and eventually, when healed, there's nowhere for it (bacteria) to accumulate-and the secretions should be milky white in color. This is the ONLY time an anal gland should be expressed, and you need to be VERY careful. (You can imagine how fond Chronos was of this routine!
At this point, I'm having my vet
check the anal gland of all of them, just so we know what is normal and what isn't. If several courses of meds haven't rid a glider of a UTI, and NO crystals are present, or if an anerobic bacteria shows up in a urine culture, I'd have the vet
check the anal glands (being careful not to damage/rupture them). If there is a problem, they will be enlarged. If they're not, then the problem most likely isn't the gland. HTH