Disclaimer-- I am not a vet-- I urge you to seek veterinary advice for Merlin: In running a shelter we chat often with owners about ferret health concerns-- from the information you have posted on FML - I suspect Merlin may have a blockage -- this COULD be life threatening.... It sounds as if Merlin may possibly have an intestinal blockage-- Get him to the vets ASAP for exam and possibly x-ray. Have you found any missing pieces of toys, foam rubber, styrofoam etc. All these are serious dangers for ferrets. If it is possible that there is a blockage ( the foaming, vomiting, and loss of weight are all symptoms of this-- then I urge you to dilute some ferretone with olive oil about 20% ferretone to 80% olive oil and let him freely take in as much as he can. This may lubricate him and help flush out the blockage-- while you are waiting to get him to the vets-- HOWEVER TAKE HIM TO THE VET FOR A CHECKUP-- often after a significant weight loss the ferret has lost strength and will go downhill very quickly. An intestinal blockage may also be caused by hairballs and it is a good idea to routinely give the ferret hairball remover such as laxatone, petromalt, etc. especially during the shedding seasons -- Spring and Fall. Good luck with Merlin and happy ferreting! [Posted in FML issue 1681]