I just began with my first chicks in April of this year. In the first group of four, I lost one around 9 weeks from an illness that started with limping and ended with paralysis and death within 4 days. I bought two more 2-week old chicks, and lost one of those at 9 weeks of similar paralysis over the course of 4 or 5 days. It started with stumbling and imbalance and ended with spastic paralysis and the classic Merek's posturing. I assumed both were Merek's, and so I knew it was endemic to my flock. I called the farm stores where I had bought the chicks and they didn't even know what Merek's was - which told me they definitely were not vaccinated. All this occurred months ago, and since then I acquired two more 9-week old Easter Eggers. All have been healthy and my first started laying in September. They free range regularly and eat the regular layer pellets. I had 4 of them laying by November, but this December, bad things started happening. 2 and a half weeks ago, my 9-month old Barred Rock started limping. She was my first layer and best layer, and also had the most inquisitive and charming personality. For the past two weeks, her limping grew worse, and at this point, she simply sits on the ground and has no use of her right leg. Her poop is normal, she is still eating and drinking, and her comb and waddles are bright red. She seems alert, but I fear that she will slowly and surely die and I expect it is Merek's. She has been moved to the "chicken palliative care unit" in my basement. I thought that an older pullet who had clearly been exposed to Merek's would have been immune - so am I silly to think it is Merek's? Is there anything else that would cause similar symptoms? Can Lymphoid Leukosis occur from the same virus that causes Merek's, or are they completely different viruses? One week ago, out of the blue, my Rhode Island Red pullet, who is 7.5 months old, was found dead under the coop. She had no symptoms leading up to this point - she was laying and eating regularly, her poop was normal, etc. Some clearish liquid had come out of her beak, but there was no signs of trauma at all. One of my 7.5 month old Easter Eggers, who had started to lay already, was found next to her and was limping on her left leg. My boyfriend put her up in the coop on the roost, and she immediately fell off like a rock. This happened two more times before she clung on enough and stayed put. The next day, she was no longer limping and has not limped since. However, she has become flat and just stands around without eating or drinking or acting like a regular chicken at all. She has also been moved to the palliative care unit, where she just stands in one place and doesn't eat or drink much at all. What is going on? Are all of these symptoms various expressions of Merek's, or am I too quick to blame that blasted virus? The other piece of information that may be important is that my RIR was crazy for dead mice. We have recently been catching them near the coop with regular flip traps and feeding them to the chickens. My RIR ate almost all of them - she just loved them and was able to wrestle away every mouse we threw to them. She had been eating them since the week of Thanksgiving, and had probably eaten about 8 total. Any ideas for causes and preventative measures in the future? I recently ordered 6 chicks that will be arriving at the end of February, and I want my flock to be healthy (and stay healthy)!!