Lost 2 hens in 2 weeks???

[Corralitos hens]

We don't have a clue what's happening!
Rhode Island last week, perfectly healthy one day found dead in the coop the next.
And today the same with a Barred Rock.
Our hens are about 2yrs old, have organic pellets and fresh well water supply, inside coop and nesting boxes, and a large outside open aviary with dirt. I dusted the flock (15 hens) for mites about 2 weeks ago b/c our rooster had a severe case of mites. The other hens did not have any or very little evidence of mite eggs. The vet said she suspected liver disease in our rooster b/c of his flaky beak and fatigue. he seems to be doing better. One other symptom is that about half the hens have had prolonged molting period with bare spots on their backs, necks, or tails...

Do we have some sort of virus in the flock? What can we do to determine the cause of death?

Thanks.

 

[ChickenCanoe]

Pick up the birds and see if they're thin, (prominent keel bone).
Are you also feeding scratch grains or scraps/treats? If so what percentage of total intake is that?
Where are you? Is it hot there?
What kind of dust did you use?
If you lose a third bird, it's time for a necropsy. Upon finding the dead bird, immediately wet it down with soapy water(dish washing liquid) and refrigerate it till you carry it to the lab or ship it.
For the time being, find the closest lab to you and call for instructions on shipping.
It's normally not expensive.

 

[Corralitos hens]

They don't seem too thin... but they aren't plump.
They typically get a couple handfuls of corn scratch daily.
It's not hot, highs this past week were in the mid 80's.
Horsefly, tick & mite dust purchased at our feed supplier. I applied it to their tail/vent area and between their wings.

What could it be?

 

[Corralitos hens]

When I got home from work I inspected the dead chicken. It was obviously a prolapsed vent. She was blocked up.
This must have happened very quickly b/c my wife only noticed her in the nesting box 2 evenings ago sitting on eggs and then found her dead the next morning. It's sad we didn't have a chance to help her.

So we assume the two recent birds are unrelated, but will keep a close eye on the rest of the flock.