I noticed a bald spot on my female glider's chest this morning. It's just under her chin, ends about 1 inch above her pouch. In the picture, my middle finger is holding her head back
She's turning 5 this summer and I have one other female glider, same age. They've been living together since they were 3 months old.
From what I'm reading, it seems to be overgrooming maybe? But I'm not sure how to make it stop. They get to play from whenever they wake up (right now about 8pm) until 1am, then they go back in their cage. Sometimes I let them play all night because they have their own sugar-proofed bedroom.
This little one in particular is overweight and mostly just likes to sleep and eat. It's hard to get her to play unless she's collecting leaves to make a nest somewhere (usually in shoe boxes).
They have 2 pouches in their cage at all times so they don't have to sleep together if they don't want to. This morning they were in the same pouch.
Attached are pictures of her chest, their cage and room.