3 dead chickens in 3 weeks

[Farmerette6]

I have had 3 chickens die in the last 3 weeks and wondered if anyone could help. The first one was a bantam that I got 4 years ago. She was already laying so I figured when she died, it was her time. Then last week and now today I have had 2 barred rocks die. I have had them about a month and a half. I took in 6 chickens from a friend, 3 barred rocks and 3 rhode island reds. The reds were laying, the bared rocks not yet. I put them in one coop and kept them there for about 3 weeks:for one to introduce the chickens with out any issues, and second to make sure none of them were sick.
A few weeks ago I had a chicken that seemed to have a cold. I separated her and started her on antibiotics. She hadn't change, no better, no worse. She only sounded "bad" she ate, drank and acted fine. I put her back in the coop with the rest after about a month. Now this. these 3 chickens have no signs or symptoms. they look fine and are eating normally from what I can tell. I haven't seen any different droppings.

I read that chickens can get bound up with eggs and it can kill them. I thought maybe when the first barred rock died that was what happened. Now I am not sure. Their eyes are fine and they acted fine the night before. In the morning they were gone.


Thanks for any advice...

 

[Eggcessive]

Sorry for your loss. With the one having symptoms of a respiratory disease, something may have been brought into our flock by a carrier. MG, coryza, ILT, and infectious bronchitis are common ones, and they can be complicated by secondary infections. The only way to determine a cause of death is to do a necropsy. Some do their own to look for egg binding, worms, digestive tract blockages, and some other problems that don't require extensive testing. Your state vet usually will perform those, sometimes at low or no cost, and here is a link to find one:
http://www.usaha.org/Portals/6/StateAnimalHealthOfficials.pdf