If you have a guinea pig who has symptoms of an ear infection, such as discharge in the ears, obvious discomfort in one or both ears, or loss of hearing, then you might want to know if they are contagious. That is an especially crucial question if you have more than one guinea pig in the same enclosure. First of all, though, you should know that ear infections are rare in guinea pigs, but they do sometimes get them. Not to mention that, if you do not catch them early enough, they can be very serious, and even affect their nervous system.
In general, if your guinea pig has an ear infection, and you catch it early enough, they are not contagious. However, as they develop, they travel into the respiratory tract and that is when things get dangerous. It is then that the infection can be passed around between guinea pigs, and become dangerous for their nervous system. So, the general rule is; if you suspect an ear infection in one of your guinea pigs, make sure to get them checked and treated as soon as possible. Furthermore, make sure to isolate them.