Diarrhoea and paralysis, could it be Marek's? in Chicken Clinic Posted May 17, 2019 Many thanks to everyone for your help and advice. We took her to the vet that day. He was not sure exactly what the cause was and agreed that euthanasia was the best course for her. She was indeed the same Flo, our dearly loved best hen. The garden feels very empty without her. thank you for tha advice on disinfectants. We will give it all a thorough clean before we start again, this time maybe with some bantam Welsummers.