Help please!

[Allipockets]

This is going to be long but I need some help and I'm very confused. I got chickens about a year ago and since I got them they have been dying. I have had 8 chickens die over the past 8 months. They all show similar symptoms that show up out of nowhere;
- stiff legs
- seizure like convulsions
- gasping/gaping
- lethargic
- vomit
- sudden death
- won't eat or drink
- stiff neck
- watery poop
- appears to lose control over head and wings/ can't walk
I brought the most recent one in for a necropsy because I suspected merricks but I just got a phone call and he said it doesn't appear to be Merricks, he said my hen wasn't in good shape and appeared to not have been eating (she hadn't eaten 24hrs before death) He's doing more testing but I'm so confused and I just really want help figuring out what this is. A bit of background info; all hens are under one year old, they have been treated with corid due to them getting coccidiosis young, they free range most of the day, have access to fresh water daily and fresh food daily, our yard is completely fenced, I live in WA state, they dont show any respiratory distress, no drainage from mouth or nose, no signs of trauma. We moved into this house a little over two years ago which I'm worried there is something in the soil. I really just want some answer so I can stop my chickens from dying. Please help.

 

[Eggcessive]

Is the necropsy being done by your state or university poultry vet? Usually, they can see small bits of tumor tissue on nerves or organs, but they also do testing for the final results. Some other problems can appear like Mareks, such as toxins in the soil, heavy metals, insecticides, and vitamin deficiencies. Hopefully your final results will give an answer, but I think there is a possibility of false negatives in testing. Sorry for your losses. Here is an article you may want to read:
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/

 

[Allipockets]

Is the necropsy being done by your state or university poultry vet? Usually, they can see small bits of tumor tissue on nerves or organs, but they also do testing for the final results. Some other problems can appear like Mareks, such as toxins in the soil, heavy metals, insecticides, and vitamin deficiencies. Hopefully your final results will give an answer, but I think there is a possibility of false negatives in testing. Sorry for your losses. Here is an article you may want to read:
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/

Thank you, it's being done by the state. He said he didn't see any tumors but they are moving on to the next stage of testing. They are doing tissue samples and hopefully will find something. I let him know that I'm concerned about there being toxins that I don't know about and he said if nothing comes back with the tissue samples there are more tests that can be done. It's going to be a week until the next test results will be available. I'm just so worried.