Sadly it was only thought to be ferrets in the USA that contracted conditions like this and adrenal , this link tells you about it , its an american publication but vets in the uk often draw from the Americans findings as lots of conditions are thought to be confind to the USA but thats not the case any more
Sorry to hear you little jill has this condition , but i hope some of the stuf in the link goes to explain the condition & the different forms of it
http://www.ferretcentral.org/faq/med/lymph.html