I'm glad I've found this thread. I've lost three Orpington cockerels in the last few weeks. Most of my chickens arrived in September and one of them I was sold as a small pullet but I was always a bit suspicious that he was just a runt cockerel (if such things exist). She/he never really thrived but then took a rapid turn for the worse - very thin, lethargic and then died early November, a couple of months after arriving and probably about 6 months old. I just kept my fingers crossed it was an inbred problem so I didn't get him checked by the vet (was quite happy to lose a small cockerel that I couldn't see would ever be big enough to breed from or eat).
But then one of my prime cockerels got sick (similar age but lovely and big even if he was always on the skinny side) - diarrhea, weight loss, lethargy, hunched appearance. He was whisked off to the vets but there was lots going on - worms which were treated but he failed to respond, antibiotics which also made no difference. Eventually he just collapsed and I took him to the vets so they could euthanise him and do a post-mortem. They even put him on a drip overnight just to see if he would revive which he did a bit but then died quite suddenly. The PM has been inconclusive - apparently lots of intestinal problems and also a number of small growths. The vet wondered about Coccidiosis so the whole flock has been treated for that.
Meantime my biggest, strongest buff also started to fail. Again worm problems were treated and he seemed to pick up a bit - he came away with us for the weekend and quite happily pecked his way around my in-laws garden. But after a week back with the flock, he suddenly collapsed yesterday - when he didn't come out of the house yesterday morning, I found him collapsed on the floor. He did seem part paralysed and was having problems breathing. By the afternoon he was fitting and he died yesterday evening. I've paid for another PM because I'm so desperate to find out what's going wrong but again nothing conclusive - some similarities to the second cockerel but no signs of the multiple growths although some sign of something that looks like peritonitis. Dramatic weight loss since they last saw him about 10 days ago (even thought I often saw him eating and drinking - seemed to drink a lot). We're now paying for various samples to be sent off but after reading this thread, I wonder whether it might be Mareks?
A bit of googling has left me wiser about what's happening inside with Mareks but not much clearer on how it manifests. Can anybody who's been through it tell me what happened? Also I know that four of the hens have been vaccinated against it, does that mean I can hang onto them? Or can they be carriers even if they're vaccinated? Or if I just get hatching eggs in next year and vaccinate at hatching would that work with just those four? And if the other hens (and one remaining cockerel) seem to be OK after a few weeks, can I assume they're immune? Also they share a big run (but not house) with four ducks and two geese - can they be affected?
Thanks for reading all of this - hope you can help,
Hester