Hello and thanks for researching this very important question!
Guinea Pigs can be allergic or sensitive to many kinds of wood-based bedding...cedar is particularly toxic, but pine chips have been implicated in some cases of respiratory symptoms as well. If you use any kind of wood bedding, switch to one of the paper-based beddings available now (Carefresh is one popular brand).
Guinea Pigs are susceptible to a number of cold viruses and can become ill quickly from eating a diet that is lacking in vitamin C. Packaged pellets are a good source of protein, fiber and other nutrients, but Vitamin C is very fragile and decays quickly under warehouse and shipping conditions.
Please go to the pharmacy right away and get a pediatric vitamin C supplement (liquid)...give 50mg today and 25mg for the next 7 days (thereafter give 20 mg every day for your pet's lifetime).
Make sure your house is warm enough for a GP...raise the room temperature to 80F degrees while she is sick, then you can keep it at around 75F degrees once she feels better. If she feels too cold, she will not take any nutrients or water.
Also get some jars of baby food fruits and veggies so that you have some soft foods to feed with a dropper to keep energy and nutrition high. You can also melt the pellet food in some warm water to feed with a dropper or spoon.
Guinea Pigs can get fungal (yeast) infections in their respiratory tract and lungs...a dietary supplement such as Bene-Bac or Probiocin (found at better pet stores, Online, or at veterinary offices) can help combat this type of microbe, or prevent it from getting a hold in an already ailing pet.
If the eye crusts shut, use a warm-water compress (NOT HOT WATER) to gently melt the discharge until the lids are free.
http://www.cavyinfo.com/html/vet.htm http://www.aracnet.com/cgi-usr/seagull/vetfinder.cgi http://cavyspirit.com/vets.htm
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Retired Veterinary Technician
Dog, Guinea Pig, Hamster, Gerbil breeder / Reptile Keeper / Bunny-Ferret-Exotic Specialist