I have 10 hens 2 are pullets but at least half are sick with…

Respiratory disease in chickens can be very hard to definitively diagnose because the symptoms look the same across several illnesses. Ideally, a veterinary exam is recommended with samples taken to identify the causative organism. I am glad you are separating the sickest one. This is best so you can closely monitor her eating, drinking and stools. You can add electrolytes (sav-a-chick, tractor supply), garlic (2 cloves crushed/gallon), and raw apple cider vinegar (1 Tbsp/gallon) to her drinking water. I would hold off on yogurt if you are using raw vinegar. It has become increasingly hard for chicken owners to find access to antibiotics. There are still some available through pigeon supply sites, and you can try Tylosin added to her water as this will treat the common respiratory infection caused by Mycoplasma Pigeon Supplies Plus — Tylosin 99% 100 grams. Since she has had loose stool, I would treat with Corid (tractor supply) for 5 days as well.

If you use the Tylosin product, there is a 2 week egg withdrawal on that product. Some have found VetRx to be helpful as well (tractor supply).

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Weird. Can you get generic Amprolium?

I will be away from my computer until this evening. I will check back in with you.

That is very thorough!

If this is a bacteria that is sensitive to Tylosin, you should see improvement over the course of a few days.

There are many differing opinions on this. Some recommend twice yearly deworming with a broad spectrum dewormer such as Fenbendazole. I personally, do not deworm unless there are symptoms (diarrhea, weight loss, unthrify). It would be ideal to deworm based on the parasites present. There is a mail in site you can send stool samples to if there is not a vet in your area to run fecal tests for you.

http://midamericaagresearch.net/instructions.php?gclid=Cj0KCQiA8dH-BRD_ARIsAC24umYDhYx1LpFna1FiFV-nF7H-IGHNJOfqVGhnr9sJA8RhnkiRkltxzcYaAlAUEALw_wcB

I am so sorry to hear about Popcorn! I am also very glad you are having a necropsy done as this is many times the only way we can get a definitive diagnosis on chickens. Please let me know when you receive the necropsy report.