My flock is basically common breed yard fowl where the hens are encouraged to roost in the coup over night to avoid predation. The Cocks have to tough it out outside when they mature as they create havoc of a night time. The most of the deaths do not seem to be connected, other than for what ever reason once the birds start to shut down they do not seem to be revive-able. I suspect two were shock related from being trampled in the scrabble to get out in the morning. One however was hard work as I noticed laboured breathing and the sound of fluid in the lungs. I tried inverting the bird, and quite a lot of liquid drained from it's mouth followed by a kind of cough and splutter. This seemed to help, so I repeated the process a couple more times, until the wheezing disappeared and she seemed less stressed. This was a "Layer" that has been past laying for about 6 months, she continued to be poorly so I separated her and then placed another similar aged bird who seemed to have the same lack of energy she did, but without the fluid issue. The "fluid" chicken died first, and the bird simply lacking vitality just settled into to a no move no eat and no drink routine until it just died. Generally speaking these are happy if just a bit lazy birds, that get reasonable feed rations morning and night, but have to tough it out during the day eating fallen bananas, mangos, palms seeds, grass and what ever is in season during the year. They lay sporadically, and I let them sit from time to time so the flock will grow, but if we get half a dozen chicks we then lose 3 birds either one or two from the chicks but mostly from the older ones so flock growth is not exponential. I don't know if chickens get heart failure symptoms like humans with oedema filling up the body, but if I can avoid getting it again I would appreciate some recommendations.