Now, I’m not a vet, but this bit here seems…Odd based on the fact that this is a recurring problem with suspected fungal infection. Antibiotics/antimicrobials are going to do very little against anything fungal. I’m also kind confused, despite knowing he had long-term mold exposure, has he never been tested or treated for fungus? Obviously I don’t know his entire medical history, but if he’s only now being tested for a fungal respiratory infection, I’d be questioning the quality of previous care.
There’s also the fact that F10, while used for nebulization, is not FDA approved and is technically just a disinfectant that contains ingredients known to cause respiratory irritation/pulmonary toxicity (Benzalkonium chloride). Here are some threads discussing its use:
That said, checking the Merck Veterinary Manual:
“Suggested treatments for deep fungal respiratory infections include amphotericin B, itraconazole, fluconazole, and voriconazole.” I’d say that’d probably be the direction your current vet will go in depending on results.