First of all, you cannot be certain the condition involves only the upper respiratory tract, that is the most obvious symptom but the boa could have pneumonia or even worse a systemic infection.
My investigational drug experience has been used to treat many rosy boa infections, a species susceptible to respiratory infections. Some cases are easier to resolve than others and require a longer course of antibiotic. Now for the big issue - Baytrol efficacy in small boas is variable and leaves scaring, can get expensive, and the toxicity uncertain but evident in many cases (I've observed some neuropathy).
Vets can be small boa killers if you are not careful, even vets with significant reptile experience.
Now revealed for the very first time, you heard it here exclusively, I hope all others reading this can benefit as well:
1) Treat your snake ORALLY using an oral feeding tube with 75 to 100 mg/kg once daily dose of the cephalosporin "cefuroxime" brand name Ceftin for human use. It is bubble gum flavored, a bit sticky, and is first reconstituted in water before use (follow the manufacturers recon instructions). You will need a vet to write the script and will treat once daily for 7 days, 10 days if symptoms are not resolved. Even in symptoms persist after 10 days, discontinue because the boa is likely recovering (keep warm for 1-2 more weeks then reassess).
2) During this period do not - unlike recommended by some vets - keep your snake in a humid environment. Place the sand boa on Sanichips, a dehydrated Aspen bedding and warmer than usual, maybe between 85-89oF.
I have treated 14 rosy boas this way - 12 with respiratory tract infections of various etiology, 1 with an abdominal abscess, 1 with encephalopathy - over the past 6 years - with virtually 100 % efficacy and no evidence of any toxicity. Amazingly this antibiotic is bioavailable through the gut (hence oral admin.) and is very well distributed. Print this message and provide the relevant content to a vet if needed, I did not intend to insult the many excellent vets out there but rather send out a wakeup call for appreciating the need for a "species-specific" therapeutic solution. My email is risen@biotrak.com.
Good luck,
Larry Risen
American Desert Boas

American Desert Boas