Hamman’s crunch; a pathognomonic sign of pneumomediastinum.

Pneumomediastinum, particularly spontaneous pneumomediastinum, is uncommon and presents a diagnostic challenge. In human medicine, auscultation of Hamman’s crunch, a crepitant, crunching noise, audible over the cardiac region in synchrony with the heartbeat, is considered pathognomonic for pneumomediastinum. This case report is the first to highlight the diagnostic utility of Hamman’s crunch for the diagnosis of pneumomediastinum in a horse. The horse’s clinical presentation differed from that of reported equine spontaneous pneumomediastinum cases, with pleurodynia (thoracic pain) and odynophagia (pain when swallowing) being prominent features. The investigation to confirm pneumomediastinum, identify potential underlying causes and rule out potentially fatal complications is described. The favourable outcome of this case is consistent with previous reports that spontaneous pneumomediastinum in the horse has a good prognosis, despite having dramatic presenting symptoms.