Female guinea very swollen

Question
My 4 year old female guinea pig has a very swollen bottom. It is very smelly, but she is still eating and drinking and looks fine. We are very worried about her and the smell is sickning. She lives with another 4yr old female pig. What is wrong?

Answer
She most likely has an infection, it could either be from a piece of bedding or hay getting lodged up in that area and causing an infection, or it could be a bacterial or yeast infection. She will need antibiotics from a vet to cure it, most likely a sulfur based antibiotic, also the vet will most likely want to swab the area and look at it under a microscope to determine what kind of bacteria or fungus it is. This can become serious fast, she may be ok now but if the infection gets into the blood stream she will get very sick and could possibly die. The smell is from the infection, just try for now wiping off the area with some antibacterial soap and warm water or wash cloth until you can get her to a vet. Let me know if you have any more questions.
Brittany