Is a guinea pig that has recovered from a URI contagious to other piggies for life (even if they are showing no symptoms)? I recently adopted 2 young boys from a local rescue to add to my existing pair aged 7 and 3.5 years. They were supposed to have been in quarentine at the rescue and their policy was that they do the introductions so I took my boys to them. They got on well with my boys so I brought them home. Less than 24 hours later one of the new boys was very ill and he had to be PTS. My vet felt that he had an infection that head spread to his inner ear and brain. She said the cause was almost certainly something my other boys had encountered in the past and were immune to so they weren't at risk. Unfortunately, though, I lost my oldest boy just over a week later. The remaining two who had been well up until this point began showing symptoms of a URI. I think grief had a lot to do with them no longer fighting off the infection. They have been on antibiotics and Metacam , prescribed by a different vet for 5 days and they are both doing well. This second vet, though, suggests that the infection will be with them for life and may return. Does this mean they are infectious for ever? Or are they only infectious if they are sneezing etc? Sorry if this is a daft question!