Some gastrointestinal upsets can be rapidly fatal. Malocclusion of the teeth can occur in the guinea pig but unlike the rabbits and hamsters, the teeth involved are not the front incisors but the back premolars and molars. Drooling and weight loss may be the only signs. Lack of vitamin C can lead to swollen, painful joints, sensitivity to being touched, weight loss, and convulsions. An injection of vitamin C and oral supplements can help correct the condition.
Some antibiotics can be fatal to guinea pigs.
Guinea pigs are born fully haired, eyes open, teeth erupted and ready to go. In fact, they are very large and look like a little version of mom. Birth weights are between 70 and 100 grams, mom usually weighs around 700 grams. I do not recommend breeding your guinea pig, but if you do, you must do so before she is 6-7 months of age. The guinea pig pelvis is unique in its ability to separate widely to accommodate these big babies at birth.