A ferret that seems to feel quite well but suddenly stops eating and vomits once or twice, producing little mucous or froth, usually has hairballs. Often little or no stool will be produced. Giving several inches of cat laxative (e.g., Doctors Foster & Smith Hairball Remedy, Laxatone) will usually relieve the problem.
If one dose of laxative has not started the ferret eating normally but he seems to feel well, repeat the dose and wait overnight. Usually two big doses of laxative will move hairballs. Check the litter box: when the hair starts to pass, you can see it in the stool. If there are no results from two or three treatments, even if the ferret does not look very sick, take him to your veterinarian for a diagnosis of the problem.
A ferret that suddenly starts vomiting, does not eat, and seems sick should be seen by a veterinarian as soon as possible. He may have swallowed a foreign body, or he may have hairballs and just needs more laxative, but he should have professional help in case the problem is serious.
Sometimes vomiting occurs early in the course of epizootic catarrhal enteritis (ECE), and contributes to severe dehydration and debility caused by diarrhea. These ferrets need intravenous fluids and emergency care.