Like we humans upper respiratory tract infections are very common and in essence there is no cure for them other than easing symptoms. These symptoms are the same as we get, apart from the coughs and the treatments are the same. A dab of Vic oinment on the nose to clear the nasal passages and Sudafed at the dosage rate of 0.2 daily the ease the flem plus hal a 2mg capsule ofgarlic oil. There is also an excellent veterinary product called Bisolvon which is a powder. Just a small amount on the back end of a tea spoon three times a day is very effective. Always feed powered medicines in from the side of the mouth then wipe the back of the spoon off the top of the mouth. Lady friends of mine have told me that this is the same way as mothers give their babies powdered medicine.
Viral, bacterial, and fungal infections of the lung can be more serious but respond well to treatment proving they are properly diagnosed.
If a guinea pig is suffering from a systemic fungal problem, see skin problems, and it develops a wheeze in the lungs, then it is likely to be caused by the fungus. The use of the drug Griseofulvin is very effective and if the animal is not already being treated with this is should be put on a course.
The bacterial infections are more likely to occur as a complication from another illness which has weakened the animal and left it open for bacterial attack. Animals that have been off their food for sometime because of dental, digestive or other problems can quite often suffer this complication. There are several antibiotics which are very effective, such as Tribrissen and Baytril. The dose rate for the Tribrissen is 0.5 orally for five to seven day. For the Baytril it is 0.4 by subcutaneous injections for five days.