When was the last time they were wormed with a good wormer?
It might not be Respiratory, it could be Gape Worm.
Syngamus trachea, a nematode worm parasite of chickens, turkeys, pheasants, and other game and ornamental birds occurring worldwide. Infection is by the oral route with earthworms, slugs and snails acting as transfer hosts but the life cycle may also be direct, by ingestion of embryonated egg or L3. There is an 18-20 day prepatent period. The condition is seen more commonly in poultry on free range where ground may be contaminated by wild birds e.g. from rookeries.
some signs can be --
Gaping.
Dyspnoea.
Head shaking.
Loss of appetite and condition
Treatment --
Flubendazole in feed, levamisole and Ivomec.
If you use Ivomec --
Ivomec injectable is used for treatment of worms in your fowl, and can be used to help keep external parasites, like Red Mites, down too.....
You will need a syringe to get ivomec out of the bottle, and you can use it to apply the dosage listed below by holding the birds mouth open, and dripping it into the back of its throat. Another method is to apply the correct dosage to a piece of bread, then feed it to the bird you are treating.
5 to 7 drops orally for adult size birds.
3 to 5 drops orally for bantam size birds.
It is recommended to worm your fowl on a regular basis, and this method will need to be repeated every 2 to 3 months to keep worms under control. In severe cases, you may want to retreat the bird 10 days after the initial treatment, to make sure you take care of the problem.
Ivomec can be purchased at most farm supply stores in the cattle section..
Chris