Anna, Think of these words TOGETHER since they so very often can have
the same cause:
bleeding
bruising
petechiae
anemia
hemorrhage
Vitamin K usage (since it is given to increase clotting and slow
bleeding)
epistaxis
etc

When you do that you have a situation in which the possibility of a
common toxin serious needs to be considered. There are human over the
counter meds which will do this, plants which can do this, garage and
home compounds which can do this, etc. You MIGHT be dealing with some
sort of illness that attacks marrow or reduces/stops clotting and your
vets NEED to be in touch with pathologists asking about that since some
illnesses are hemorrhagic and a vet pathologist like the ones at MSU in
my sig lines should be involved, BUT there are types of poisoning which
do this and so toxicologists such as those at
http://www.aspca.org/pet-care/poison-control/
NEED to be involved. You even need to consider if anyone in your family
is using estrogen cream which the ferrets may be licking off, so do
consider toiletries, too.

Read the relevant sections in the ASPCA sit above and in
http://www.veterinarypartner.com/Content.plx?A=669

<http://www.petmd.com/ferret/conditions/skin/c_ft_petechia_ecchymosis_bruising>

which can also be found on one page at
http://www.petmd.com/print/10107
http://ferretcongress.org/sym2008/PittsPDF/infect.pdf
http://www.ferrethealth.msu.edu/Diseases/Endocrine_And_Hematopoietic.pdf

(Besides the estrogenic cause of bleeding see the splenomegaly section
and DEFINITELY see the Aleutian Disease section since that is in the
UK as well as many other places and it is an infectious disease among
ferrets (but as far as I know NOT among dogs) AND it can cause
coagulation defects and much more)

A common theme appears to be coagulation defects:
QUOTES
>Date:    Thu, 23 May 2013
>Fiora ... became ill first, in January. We found her semi-conscious
>and took her straight to the vets, where they put her on fluids and
>antibiotics, but had no idea what was wrong with her. It was noted
>she had significant 'bruising' and swelling to her lower abdomen,
>petechiae (sp?) to her face and bruising to her mouth.
>
>Din... vomiting blood and there was frank blood in her stool were a
>couple of odd features to this disaster.
>
>Gwen... Her tongue was black, as if it were bruised and there was
>bruising to her face.
>
>Spike...  had a bruise to his mouth
>
>Buffy... bled from her anus and collapsed again.
>
>Emrys... bled out from his mouth... blood appeared to emanate from
>either his trachea or cranium
>
>Buffy started to have blood coming from her mouth
>
>My dog Shadow is also ill...  blood in his urine.
>
>we have eliminated all the common causes including rat poison
>(warfarin), ethylene glycol, trauma (even the pneumothorax was not
>proved to be traumatic). The ferrets were vaccinated against CD and
>treated for mites with ivermectin spot-on (from the exotic's vets,
>and after two had already died). We are not aware of any pest control
>in the area or agricultural spraying and the ferrets are fed a
>combination of quality ferret kibbles, cat milk, egg and cooked
>chicken. We also use Cathys Ferretoil as a treat.
>
>Date:    Thu, 23 May 2013 08:57:44 +0100
>The floor is lined with vinyl flooring.

END THAT SECTION OF QUOTES

Sukie's note: for safety's sake check into what that and the glue can
outgas or what may be possible to ingest from the glue involved, ditto
other building materials.

>We clean the shed with Safe n Clean pet disinfectant and hot water.

I am unfamiliar w the product but is it possible that you have a batch
which has been tainted one way or another?

>We thought the shed was well ventilated, but when the temperature

Yes, that shed is definitely not safe temperature-wise for them from
what you wrote both days.

>Our vets are still not certain it was heatstroke by the way -- the
>mystery was why the ferrets didn't just go outside.

>All the obvious poisons have been ruled out.

Which is why a toxicologist has to be consulted, and you may need to
consider if your neighborhood has any unbalanced individuals who would
poison animals (Rare but it happens, having grown up on a street with a
boy who did exactly that.) or any well-meaning person who would give
them OT meds, like some human over the counter pain killers which WILL
cause much of what you are seeing.

>I do not appreciate messages suggesting I'm an abusive, neglectful
>ferret owner and particularly messages that I should give my remaining
>ferret, who is still sick, back to a rescue.

Remember to test for Aleutian Disease. If your ferrets have it then the
shelter might also have it but be unaware.

>Date: Thu, 23 May 2013 12:00:24 +0100
>
>I've just spoken to my dog's vet. She has been in contact with the
>other vets (exotics vets and the rescue centre's vets) and has also
>told her colleagues about the situation in case they have any ideas.
>
>Natalie, our exotics specialist vet says she has never come across a
>situation like this in her career, which seriously worries me, but we
>just have to wait for the pathology results.
> ...
> Another couple of ideas I want to throw into the mix:
>* Aspergillus fungus. We don't have the same species as causes so much
>  damage in the USA, but its still a potential problem. Not sure of
>  the symptoms however.
>* Hepatitis. Before Fiora died, her liver ALT levels were 15x high
>  normal. One vet told me "any animal that has a liver could get
>  hepatitis" but he isn't a ferret specialist.

Ferrets can have high ALT levels and have them mean nothing. Watch
the Bilirubin numbers with ferrets. The original site for these vet
pathology articles is now gone but the relevant sections are in these
two:
http://ferrethealth.org/archive/FHL3606
http://ferrethealth.org/archive/FHL217

>* Mushrooms. A woman in UK died recently from eating deathcap
>  mushrooms she found in her garden. But could the spores be dangerous?
>* Lung worm. We have a lot of slugs and snails this year.
>* Lyme disease
>* Floor glue or window sealant
>* Heavy metal poisoning

I think you ask some good questions below and note the possibilities in
the links I included. The most common heavy metal poisoning encountered
in domestic ferrets might be zinc poisoning from galvanized metal but I
do not offhand recall if that causing bleeding.

Sukie (not a vet)  Ferrets make the world a game.
Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.miamiferret.org/
http://www.ferrethealth.msu.edu/
all ferret topics:
http://listserv.ferretmailinglist.org/archives/ferret-search.html
"All hail the procrastinators for they shall rule the world tomorrow."
(2010, Steve Crandall)
A nation is as free as the least within it.

[Posted in FML 7798]