Sick ferrets need special attention. They often have a reduced appetite when they need good food to heal. The secret to feeding a sick animal is to offer it a small amount of a palatable, nutritious food frequently. The patient will often take a few bites of anything you offer, then will not return to that food again. However, every time you bring food, he will taste it. He will eat a much larger quantity of food if you offer many small meals than if you leave him with one large meal. When the ferret has lost interest in the special food, remove it, so that it will not get sour or stale and cause him to reject the same food next time you bring it.
Jills need about 200 calories and males over 300 calories a day to maintain their body weight. Chronically ill ferrets have been maintained on nothing but Nutri-Cal®, Ensure Plus, Drs. Foster & Smith Vitacal®, or other easily digested nutritional supplements for months at a time. Some sick ferrets will eat their own pelleted diet only if one of these supplements is mixed with it.
The outbreak of epizootic catarrhal enteritis (ECE, a highly contagious viral disease of the intestine) in 1993 stimulated some desperate and resourceful ferret owners to invent a disgusting-looking but apparently palatable mixture to support very ill ferrets until they began to eat voluntarily. They called it "Duck Soup." Although ferrets may eat Duck Soup on their own, it has a porridge-like consistency that makes it possible to force-feed it when necessary. It is made in relatively large batches, and frozen in ice-cube trays or small plastic containers, so that it can be thawed and served fresh without having to stop and make more every day. There are many variations: choose one that your ferret is likely to prefer.
You can make your own Duck Soup using whatever pelleted food the ferret likes best, and adding palatable, nutritionally balanced liquids to make it the right consistency. One simple additive that many ferrets find palatable is chicken broth. Other possibilities include strained baby chicken, beef, or veal, human nutritional supplements such as Ensure or Sustecal (ferrets may express distinct flavor preferences), and vitamin and mineral supplements. Critically ill ferrets have been maintained for months on Duck Soup, and eventually began to eat more normally. Bringing an animal through this kind of crisis requires intense energy and devotion, but also cements a bond between the caregiver and the sick little ferret that will never be broken.
For more Duck Soup recipes see http://www.miamiferret.org/fhc/duck_soup.htm