I have a few birds that are between 2 and 4 months old. They start to get lethargic and then develope lesions on their eyes and they have some discharge from their nostrils. The lesions on some birds have got so big the eyes completely close. They become extremely lethargic and about half of them die. But it takes weeks to kill them. What is it!?!?[/IMG]
Scabs on the head are often due to fowl pox, which is a viral disease carried by biting insects like mosquitoes. There is no treatment (it will eventually resolve itself in 2-6 weeks), and it fortunately isn't usually fatal. However, since your birds exhibit more symptoms (discharge, lethargy, death, bad smell), I think it is more likely that they have a serious respiratory disease. Infectious Coryza, in particular, comes to mind. Coryza can sometimes be treated with antibiotics like Tylan50 injectable or certain sulfa drugs. Affected birds remain carriers, though, and will continue to possibly spread the disease throughout their life. Because Coryza can't truly be eliminated from birds, it is often best to cull the flock, disinfect the area, let the coop/run stand empty for several weeks, and then try to introduce new birds.
I agree. Coryza can cause a foul odor around the head, swelling, and crustiness. I think that it is possible that your birds have both Fowl Pox and Coryza. Coryza or other respiratory diseases often accompany Fowl Pox, due to a weakened immune system.
Are they getting eye drainage that is crusting around the eyes, or are there scabs of some sort? Scabs or lesions around the eyes sound like fowl pox, but dried eye drainage can resemble a lesion. Usually swelling around an eye with drainage along with nasal drainage may be a respiratory disease. Infectious bronchitis, MG, coryza, and ILT are common diseases to look at, but MG and coryza are the ones that usually cause eye swelling. Antibiotics such as Tylan50 injectable (given orally or by shots into the breast muscle) and oxytetracycline (given in the water) are used to treat symptoms, but respiratory diseases make carriers of all in the flock including ones not appearing sick. Did you get these birds from someone else, or recently have added an older bird who may have been a carrier? After re-reading your title, and seeing that part about the bad smell. it does sound like coryza. This is a disease that many people choose to cull for, but you may want to get a necropsy done by your state vet on one of your sick birds to confirm it. Here is a good link on respiratory diseases that you may want to read: http://edis.ifas.ufl.edu/ps044
Read this and see if the symptoms fit...I believe it might well be coryza: https://www.backyardchickens.com/t/912104/chicks-sick-help
Almost a year ago I had fowl pox go through my flock. Confirmed by a vet. And this year the Mosquitos have been really bad the past month so I think you are right about the fowl pox. I was hoping not to have it be coryza. There isn't a ton of discharge from the eyes but I bet you are right. I bet it it a combo of fowl pox and coryza.
Usually with fox pox, the chickens who get it will be immune for life, as long as it is the same strain which is probably the case in your same area. I don't know if she was one of those who got it. If you call around in your area to vets, or contact the Dept of Agriculture in your state, they can tell you how to get one tested. Sulfadimethoxine in the water and Tylan 50 injectable can be given together to treat coryza. In your state they offer free necropsies for up to 2 birds a year at UC Davis if you ship a refrigerated (not frozen) body. Here are 2 links below to help: https://www.backyardchickens.com/t/799747/how-to-send-a-bird-for-a-necropsy-pictures http://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf