Utilizing rodent ultrasonic vocalizations as a non-invasive technique

SOT 2025 -- Inhalation toxicology studies in rats are conducted to support development of therapeutics and risk assessment of chemicals. Respiratory tract toxicity is often not detected at a clinical level in rats, until histopathology is performed following the terminal euthanasia. Squamous cell metaplasia of the larynx is an adaptive response to local irritation and can be accompanied by adverse findings such as necrosis, ulceration and inflammation. Ultrasonic vocalizations (USVs) may be behavioral and are produced by a laryngeal neuromuscular mechanism that can be influenced by structural changes. “22-kHz calls” represent a negative, perilous response, and “50-kHz calls” represent a positive response or interacting with a complex environment. The objective of this study was to test whether USVs correlate with clinical observations and microscopic pathology in the larynx following inhalation of a toxicant.