Guinea pig problems can include:
Respiratory infections, diarrhea, scurvy (From Vitamin c deficiency), tumors, constipation, urinary problems.
Infestations can also occur. Your guinea pig can be infested by lice, mites or fungus.
Upper Respiratory Infection:
This is the most common among guinea pigs. It can be for a number of things, including the type of bedding you use (stay away from pine or cedar, only use fleece or carefresh or aspen shavings!)
They are fatal. If you don't get help right away after seeing these signs, you will lose your guinea pig. Please, if any of these signs occur, take your guinea pig to a vet!
Signs of a URI (Upper Respiratory Infection):
~Refusal to eat or drink
~No feces (as a result of not eating)
~Labored breathing, wheezing
~Crusty eyes, eyes that are almost sealed shut
~Discharge from eyes or nose
~Dull and/or receding eyes
~Rough or puffed-up coat
~Lethargy, hunched posture
Like I said, if any of these signs occur, seek medical attention immediately! URI's spread quickly and can kill your guinea pig!