Thank you all for your input on the lack of down on the first born baby, I was unaware of this aspect of coloring. Though in making my comment about FTT, I didn't take the small quantity of down visible into consideration. While I found it curious, I have not seen this in babies sick or otherwise because the only dilutes I have cared for were as adult rescues.
So, my comment was regarding the size, and it does remain a valid consideration when weighing whether or not to treat though I prefer to have more indicators pointing in that direction. FFT is one of a wide range of presentations for salmonella and Baytril (Fluoroquinlones) is the drug of choice when treating salmonella period.
May one treat a baby with this medication? Yes and I have done so under veterinarian and avian veterinarian input. Again, Avian vets use this medication or Cipro (again Fluoroquinlones) which is very well tolerated when correct dosing is followed. Studies that have been done on giving this medication were done on puppies not baby birds whose skeletal system is different and this is what is always cited to me by Avian vets. Some pigeon formularies that are older may not reflect this but this is an updating failure and not current mainstream thought on the topic in Avian medicine.
I have saved too many babies with Baytril and rebuilt their gut flora to walk away and let the baby die because I withhold treatment.