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]