what do I do next?

Recently, I have lost several chickens to some sort of progressive weakness. It has affected all of my Polish (except for the frizzle) and I have lost the two hens. The two cockerals have good days and bad. One has a wry neck. I have lost one cochin to it, he eventually just wasted away, and the second (his brother) was at the good day/bad day point (until he was attacked and killed by the other chickens yesterday - so I don't know if he would have recovered or not). It also killed one of my Am roos. Now, one of my Am pullets seems to be affected. would really like to be able to save her and the two polish roos that have it, as well as prevent it from spreading...

So, here are the symptoms:

progressive weakness (NOT paralysis)
pullets just get weaker and die, cockerals seem to lose more bodily control & get wry necks
affected birds WILL try to eat and drink
NO upper resipiratory symptoms, clear eyes, no mites (that I can tell)
maybe diarrhea - hard to tell, b/c by the time I realize a bird is affected (basically, b/c I can catch it), they don't eat well & therefore don't poop well
eventually death - although some seem to be hanging on longer than others

Here is what I have tried:

Sulmet
Wazine
tetracycline
electrolytes

I have also tried Ivomec, with mixed results - the Am roo I gave it to died, but the Polish cockeral I gave it to is still alive...with a wry neck.

I should also mention that all of the affected birds are from two specific breeders, although I'm not overly sure that's relevant.

What am I supposed to try next???

 

Pickle - I have contacted the MD Dept of Ag, poultry extension - all of the information you gave me before, and then some. I did not get any responses (phone and/or e-mail). I hope I'm not coming across as crying "foul" with no action - I really have been trying. I did, today, find an avian vet, and took one of the sick birds. He did a fecal (found a *few* coccidia, but not enough to warrant the condition she presented in) and pulled blood. He could not find anything on the basic presentation, but called the state vet, who pointed him to a specific person in the Dept of Ag, who responded to HIS call - finally, progress! They suspect Mareks but admit that it is a very unlikely presentation, and that it is odd that the cockerals and pullets present differently. But, since I can't seem to cure it, the only answer now is a necropsy. Basically, now, I am providing supportive care over the weekend and will determine on Monday (if she has not already died) whether she is improving (which will make the decision easier) or not...at which point I will cull her and possibly the other affected birds and the vet will ship them up to the state vet for me.

Then, perhaps, we will have an answer. Probably not the answer I want (although, at this point, an answer is better than nothing at all). But, believe me, in addition to trying every medication under the sun, I have been trying to contact everyone under the sun - apparently, vet to vet is a much more effective route to take.

And the vet was very sympathetic, which made my heartbreak a little more bearable.

So, a premature RIP to Blue, Cody and Chip - I so desperately wish I could save you!!!