Inhaled ICG shows early promise for canine lung imaging

A new preclinical study in Veterinary Surgery reports that near-infrared fluorescence imaging with inhaled indocyanine green, or ICG, was feasible and appeared safe in six normal purpose-bred dogs undergoing thoracoscopy. Dogs received inhaled ICG at 0.1, 0.5, or 1.0 mg/kg, and all showed real-time pulmonary fluorescence, with first fluorescence appearing at a mean of 1.5 minutes. Stronger signal was seen at the 0.5 and 1.0 mg/kg doses, and the authors reported no clinical respiratory compromise or histologic abnormalities over short-term follow-up and repeat biopsies at six months. (researchgate.net)

Why it matters: For veterinary surgeons, this is an early but practical step toward image-guided pulmonary surgery in dogs. The appeal of inhaled ICG is that it lights up normal lung parenchyma quickly, which could eventually help make lesions or margins easier to distinguish intraoperatively without relying only on palpation or white-light visualization. That idea has precedent: a 2020 JAMA Surgery study in human lung surgery found inhaled ICG highlighted healthy lung tissue while tumor tissue showed little signal, supporting margin detection, and a 2023 canine case series using intravenous ICG in 40 dogs with pulmonary masses suggested fluorescence imaging may help assess resection and nodal disease, though margin performance was imperfect. (researchgate.net)

What to watch: The next key question is whether inhaled ICG can reliably distinguish actual pulmonary lesions, margins, or occult nodules in clinical canine cases, not just normal lung tissue. (researchgate.net)