If you are considering getting a ferret, you should be aware of diseases and conditions that are common to ferrets. Don't think of a ferret as a diseased animal - they aren't. However, they do get illnesses that may shorten their lives.
The first thing a ferret owner should be aware of is intestinal obstructions. This is not a disease, but a condition caused by your ferret swallowing something that cannot be digested. Like small children, anything a ferret gets a hold of goes directly to their mouth and they may swallow it.
Intestinal obstruction is the number one cause of deaths among ferrets. Unfortunately, it is a slow and painful death for the ferret if you don't realize that there is a problem and seek treatment from the vet. Items that the ferret may want to chew are also a danger, because small pieces can come off and be swallowed. Ferrets are especially fond of rubber items, like sink stoppers. A ferret is most likely suffering from intestinal obstruction if he is lethargic, vomiting, has problems having a bowel movement, or refuses to eat or drink. He can die very quickly from this.
Lymphoma is also a common disease that ferrets may experience. Lymphoma is cancer, and is indicated by diarrhea, weight loss, weakness, and swollen lymph nodes. In most cases, your vet can help you to make your ferret more comfortable. He may even try radiation therapy, which is expensive but there is no real cure for lymphoma.
If your ferret passes bright green feces, he most likely has ECE or Epizootic Catarrhal Enteritis. This is highly contagious, and known as the Green Slime Disease. The ferret may vomit as well, and is at high risk for dehydration, malnutrition, and ulcers. He may also have seizures. At the first sign of green, slimy feces, you should contact your vet for treatment.
You may have a diabetic ferret on your hand. Insulinomas are growths on the pancreas. They cause the pancreas to release too much insulin, which in turn makes your ferret suffer from hypoglycemia. If your ferret is weak, lethargic, or sleeps too much, call the vet. Serious symptoms include vomiting, disorientation, and seizures, among others.
Adrenal disease is also common among ferrets. Adrenal disease means that there are growths on the adrenal gland, which may or may not be cancerous. Common symptoms of adrenal disease include hair loss, starting just above the tail and moving up the back. The ferret may also experience weight loss. If the ferret is a female, the vulvae may be swollen as well. A ferret usually won't suffer from adrenal disease until he or she is between three and four years of age.
The good news is that you don't have to diagnose your ferret. All you have to do is pay attention. Anytime there is a change in eating habits, sleeping habits, play habits, or bathroom habits, call the vet and get the ferret checked for a potential problem.