I Get White Stuff From Anus My New Guinea Pig Has White Stuff In It's Anus. Help?

My new guinea pig has white stuff in it's anus. Help? - i get white stuff from anus

I told him that his house and is about 7 1 / 2 weeks. I recalled her ass when I see him in his new cage, but he threw in his lil igloo before he could get it again.