Upper respiratory infections are rare in healthy ferrets that are kept in a good environment and have limited to no contact with sickly animals. Ferrets that are most susceptible to infections include kits, older ferrets, ferrets with weakened or suppressed immune systems, and ferrets living in unhealthy conditions (dirty cage, too warm or too cold, etc.).
The signs of an upper respiratory infection include:
Nasal discharge - clear, yellow, or green
The color of the nasal discharge will probably give your veterinarian an idea of how severe the infection is, and whether or not it can be treated with antibiotics.
The decreased appetite is due to the congestion. Ferrets with upper respiratory infections cannot smell their food, and it's hard for them to swallow with blocked nostrils, so they eat less.
A respiratory infection can occur when a ferret is exposed to another person or animal with an infection. It can also develop when an animal lives in a dirty environment that is full of bacteria. Additionally, a respiratory infection can be a secondary infection to another disease such as canine distemper.
Most minor upper respiratory infections should clear up in a couple days, just as they would in humans, especially if the ferret is in otherwise good health. If you see signs of a respiratory infection that last longer than two days, schedule a veterinary appointment. Your ferret may need antibiotics or other medications.
There are a few things you can do to help your ferret be more comfortable while he is recovering from his respiratory infection.
Add water to his kibble, warm it in the microwave, and serve it as a warm mush to stimulate his appetite and make it easier for him to swallow.
Wipe excess discharge from around his nose with a tissue.
If the air in your house is dry, put a humidifier near your ferret's cage.
If he has lots of nasal discharge, put him in a small room with a vaporizer to loosen the mucous and help him to breathe easier.