Yes, ECE (Epizootic Catarrhal Enteritis) is a virus, a coronavirus.

There have been those who think that ECE is easy to go through, partly
because some of them have called almost anything ECE (many things cause
diarrhea), but ECE itself is contagious for a great many months, and
only the symptoms and the secondary infections can be treated. Some
other people discount the possibility of ECE too easy with severely
ill ones because of differences which can occur with symptoms.

Here are some URLs to help you:

From the Dr. Bruce Williams, the person who first figured out that it
is coronavirus:
http://www.afip.org/ferrets/ECE/ECE.html

Also from him the type of diet which is easiest on the gastrointestinal
tracts of infected ferrets:
http://www.afip.org/ferrets/babyfood.html

Hydration is essential. Some ferrets with ECE get kidney damage due to
dehydration so knowing how to give subcutaneous fluids and getting IV
when those are not enough can save some ferrets.

Two things to have the treating vet or one of the vet techs there teach
you with hands-on demonstrations:

1. How to safely give sub-cu fluids

2. How to safely "force-feed". Done wrong syringe feeding or forced
feeding can cause a ferret to inhale the food or fluid and that can
cause a very hard to treat case of pneumonia, so learn your techniques
from a professional.

Mouth pain could be from mouth ulcerations caused by kidney damage
or caused by secondary bacterial infections. I do not know if the
mouthwash, Listerine, is in your country, but a cotton swab with
Listerine on it held for a short while against a mouth ulcer will help
it heal much faster. When our vet first told us about that trick I
doubted it, but experience soon made me realize that it does help a
lot.

Here is a write-up which links to four locations, with two of those by
veterinarians:
http://www.miamiferret.org/fhc/ece.htm

Here is how to tell what different appearances of the bowel movements
mean:
http://www.miamiferret.org/fhc/poop_chart.htm

Dr. Bruce Williams has also mentioned that starches can create more
yellow look to the feces.

Some useful past posts:

http://ferrethealth.org/archive/SG1245

http://ferrethealth.org/archive/SG284

http://ferrethealth.org/archive/YG13196

http://ferrethealth.org/archive/YG12815

http://ferrethealth.org/archive/YG12391

http://ferrethealth.org/archive/YG12071

[Posted in FML 5463]