So many diseases out there! I wonder if the heat and dry environment here helps reduce disease. I always enjoy your informative posts.I'm thinking Nohope actually has two separate issues. I think he definitely had diptheric and dry fowl pox simultaneously back in November, which he's recovered from. The fact you said he's always been a little unsteady since he was a chick is making me think that he's always had some sort of central nervous system problem and that's what's affecting him now. It could be down to any number of causes e.g. viral, genetic, protazoan? Or maybe something like infectious tensynovitis? It seems to fit some of his latter symptoms. You said he's tested negative for Mareks and other ALVs?
Did you say JoJo had Mareks? Mareks is very contagious but does have different levels of virulence.
In view of the variable nature of the viruses involved and the factors limiting birds showing symptoms, it is possible for birds to present in different ways. Mortality in flocks can also vary, anything from 20% to 80%. Not all infected birds will even show any signs of illness, let alone symptoms. Presentation of Mareks in individual chickens is dependant on:
- strain and dose of virus
- age at exposure
- maternal antibodies
- host gender and genetics.
- strain and dose of vaccine virus, if birds are vaccinated
- several environmental factors, including stress.
It's now consided ubiquitous in the environment and all flocks are now assumed to have been exposed to the virus. Given that Polish chickens are highly susceptible to Mareks, it would make sense your Polish birds have been more adversely affected. What doesn't make sense is that your Silkies weren't, as they're considered highly susceptible to Mareks infection too. I don't know of any inherent problem with lavender genes in terms of Mareks either.
My only other thought at the moment is the environment of the coop itself, specifically the poor drainage. With that we're back to things like aspergilliosis, botulism, Clostridium septicum, C perfringens type A, and Staphylococcus aureus, e.coli, and heavy metals leaching up through the wet soil.
The gangrenous dermatitis often occurs as a secondary condition when a bird is immunosuppressed by something like infectious bursal disease, chicken infectious anemia, reticuloendotheliosis and reovirus. It has also been noted after systemic fowl pox outbreaks.
Is there any old lead paint anywhere on or in the coop? Zinc hardware cloth fragments they might have ingested? Can you get a blood test done for heavy metal poisoning, perhaps?