Respiratory issues in chicks 2-7 weeks

[Bregham91]

I have 40 total chickens. Bought at a local feed store. I will put the day I bought them the breed and how old they were when I purchased.
3/16:
1 Buff Orpington- 1 week old
3 Blue laced red Wyandotte- days old.
3/22
1 dark brahma -days old.
3/29
1 black sex link 1-2 weeks
3/30
6 Ameraucana mix days old
3 light brahma days old
4/20
4 white Plymouth rock 2ish weeks
4 black astrolorp 2ish weeks
4/23
10 rhode island reds 2 weeks(ish)
5/1
Whitings true blue 2 ish weeks

So....all my chickens prior to the RIRs never showed any distress at all. Then 2 days after I purchased the RIRs I noticed the crackled breathing and sneezing. I already had introduced them to the others and since then it has spread to -FOR SURE-
5 ameraucana, 2 light brahma, 2 Plymouth rock, 4 RIR, and 3 all astrolorp not including my already sick and seperated true blues. They are all quarantined inside amd I have tried:
Switching bedding twice (from hay to straw to shavings)
Switching to medicated feed(I know its for their guts but why not throw it all at them)
Putting probiotics in their water
Natural herbs like oregano,thyme, basil, cinnamon
Saline drops
Vet rx

And then I was looking at some meds I have here from past illness in my family. And I have an antibiotic that is tetracycline. Yay right because we cant get this stuff without a prescription anymore . So they are 100mg and I disolved it into 1/4 cup of water. Then gave the chicks .5 ml of that. I dont know if that is enough but I'm trying to figure out the frequency and the volume they need to be given. Also any tips from the pros out there would be appreciated!

 

[Pyxis]

Well, it certainly sounds like a respiratory disease since you've tried eliminating environmental factors and that didn't work, and it's contagious and spreading.

So here's the bad news - chickens don't get colds and illnesses like we do, where they get sick but then they get better and it's gone. They get chronic respiratory diseases that never go away. You can treat the symptoms, but whenever they are stressed, they will just have another symptom flare up and need to be treated again. They will also pass these diseases to any other birds they come into contact with.

What this means is you have two choices here. You can either cull all the chicks, wait a couple months, and then start over with a flock that's not sick. The other option is treating them, being prepared to treat them over and over as they show symptoms again, and closing your flock, meaning that no bird ever leaves your property. It stays there for life or until you cull it. You cannot sell or give away birds because then you would infect someone else's flock.

My first step would be to find out what this is. If I were you, I'd either cull one and send it off for a necropsy, if your state offers free necropsies. If not, then I would do Zoologix's poultry respiratory panel, which will cost you $98 and only requires that you get three mouth swabs from one of the sick birds.

From there, you will know what it is and what medicine can be used to treat it, if a medicine will even work - some of these diseases are viral and antibiotics will do nothing for them. Different diseases respond best to difference medicines.

Or, you might decide to just call it a loss and cull the chicks and start over with a flock that's not infected.