A drug that I have used in the past is LS-50. It is a combination of two drugs that treats CRD very effectivly. For treatment I use 1 tablespoon per gallon of water for a full 7 days.
With most illnesses in chickens they will only pop up when the birds are under stress. And as you have found out it doesn't take much to stress out a chicken. Nature intended them as a prey animal to be short lived in the wild. Something as simple as a dog or cat walking near the run will stress them to the point of illness. I go as far as wearing the same basic color clothes when I take care of the birds, they don't like change.
We have a host of predators here too and we are growing a set of dogs to watch the livestock because we still have a few RIRs that need watching. If you free range you will get losses and our biggest threat here is from stray dogs and coyotes in the daytime and Great Horned owls at night. All of our breeding projects and show birds are well protected in pens. I do keep a few birds free range however to help lead away any threats to the more valuable birds and I am slowly switching them over to game hens because they are faster and survive threats better. Plus as you can see I am often up at odd hours and I go outside often to check on the critters.
With most illnesses in chickens they will only pop up when the birds are under stress. And as you have found out it doesn't take much to stress out a chicken. Nature intended them as a prey animal to be short lived in the wild. Something as simple as a dog or cat walking near the run will stress them to the point of illness. I go as far as wearing the same basic color clothes when I take care of the birds, they don't like change.
We have a host of predators here too and we are growing a set of dogs to watch the livestock because we still have a few RIRs that need watching. If you free range you will get losses and our biggest threat here is from stray dogs and coyotes in the daytime and Great Horned owls at night. All of our breeding projects and show birds are well protected in pens. I do keep a few birds free range however to help lead away any threats to the more valuable birds and I am slowly switching them over to game hens because they are faster and survive threats better. Plus as you can see I am often up at odd hours and I go outside often to check on the critters.