I am not a vet, so I can only give anecdotal info.  based on personal
experience.  First, a hairball WILL NOT SHOW UP ON X-RAY.  I went through
this with one of my babies this year.  Hair does not show up on xray, or
else the xray would not work.  If your vet is saying your ferret is too ill
for exploratory what does he suggest?  do the blood tests show metasticized
lymphoma?  adrenal disease?  How old is the ferret?  I think if possible
getting your ferret stabilized enough to do exploratory is the best option,
no other test ie.  blood, x-ray ultrasound, barium will give you as
conclusive a result.  I lost my first ferret Tigger this year due to a
massive hairball in his stomach which did not show on x-ray.  Unfortunately
the emerg. vet told me he had cardiomyopathy and I had tests done for
that, as well as 2nd and 3rd opinions, and was left facing that he might
have a blockage or tumour, if we didn't stabilize his heart(more expensive
tests) he might not make it through surgery etc.  unfortunately with vets
advising me there were no good options (I even had a friend do Reiki, and
"communicate telepathically" with him) I waited.  When Tigger couldn't walk
one morning I knew I had no choice.  My vet felt he probably wouldn't make
it through surgery, but he was a strong boy, and loved me very much and he
did.  He had a massive hairball, larger than my little finger and his
spleen was 15cm.  (normally 5cm.) Unfortunately, I waited too long.  He
wouldn't eat on his own.  Force feeding did not work, and he slipped into a
coma three days later.
 
I had wanted exploratory surgery done the first time I took him to the
emerg.  Exhaust all your options, if I had known more and acted sooner my
baby boy would still be with me.  He was my first and we were never apart
for more than a week in his too short, four and a half years of life.
 
Lara, with Smokey, Chaos, "baby" and angels Fredo and Tigger.
[Posted in FML issue 2446]