I think the cause of the problem should be found first,usually poor ventilation,if you have ample ventilation then the amount of pigeons you have in the breeding section. As for products to clear respitory problems these are Prescrption Only Medicines in the UK.Not knowing what's available in the US. you might ask the same question on a US site.I think my choice would be Doxy T.as I said though POM. Treating young birds in the nest for resp.Not too sure on that,my choice would be the bin. JMO Lindsay