If proper care isn’t taken, it can turn into pneumonia, which is deadly. When the ferret is sick with a respiratory infection, it usually doesn’t want to eat and drink as much as normal. It is important to keep the ferret hydrated and fed.
If you can get the ferret to a vet, that is the safest thing to do so you can be sure it’s not already pneumonia or close to it. We generally prefer not to start on antibiotics until we are concerned about pneumonia.
Get some unflavored Pedialyte (generic is fine). Give your ferret this with a syringe, as much as 75 ccs each day. Use regular water in the water bowl, so the ferret has access to both. Be sure to refrigerate the Pedialyte. Any left needs to be thrown out after three days.
Feed a soup mixture to your ferret, using Pedialyte to mix it rather than water. If necessary, let the ferret lick the soup off your finger or a baby spoon to get it to eat as much as possible. As a last resort, force feed the ferret. Be very careful. It is possible for the ferret to inhale some of the soup because of the congestion. This would create pneumonia for sure.
Run a humidifier in the room where the ferret is kept.
Keep the ferret confined to a cage as much as you can. Cover the cage on all sides and half the front to keep it calmer and warmer
Give the ferret a steam treatment two to three times a day. Boil a medium to large pot of water. (If possible, add two to three drops of Eucalyptus or Tea Tree Oil to the water.) Put the ferret in a carrier or small cage. Put the pot of hot water beside the cage or carrier, then cover all with a blanket. Make sure the steam from the pot can rise (don’t have the blanket directly over the top of the pot). You want the ferret to be able to breathe in the steam from the hot water to loosen up the congestion. Let the ferret breathe in the steam for five to ten minutes.
Make sure the ferret has plenty of soft blankies in the cage that it can cuddle into to keep warm.