I have lost a total of 4 silkies over a 6 month period of time. They become weak and fall over. Stop eating then stop drinking. I've tried vitamins and deworming. I have the first one necropsied by a vet who said it was vitamin a dificiency due to being winter and no greenery to eat. Well its middle of summer with green everywhere and i just lost another one. The necropsy revealed no signs of merek's disease or worms. Does anybody have any other ideas?