Oh wow!! Interesting! I wonder if it is common in this breed. Her issues started out with her neck twisting (like wry neck) but then progressed to her being completely limp in just a day and thought she was going to die. We thought it was Marek’s and so did the vet, but I decided to provide supportive care and tube feed her and she very slowly but surely got better. She has a little bit of residual effects from it because her aim is a bit off when she tries to peck around and eat but she makes do . Love the Sussex’s, such spunky little breeds!!My little SS also has neurological issues. She is 2 now but was really slow to develope, didn't lay eggs until she was a year old. Now she kind of has a head tilt and looses her balance when she scratches around. We love her lots and she is very sweet, gives me about 5 eggs per week.