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Prospective Randomized Clinical Trial of Doxepin in Canine Laryngeal Paralysis

Principal Investigator: Mark Rishniw

Department of Clinical Sciences
Sponsor: American College of Veterinary Internal Medicine Foundation (ACVIM FDN)
Grant Number: 15-11 Zoetis
Title: Prospective Randomized Clinical Trial of Doxepin in Canine Laryngeal Paralysis
Project Amount: $11,880
Project Period: July 2015 to July 2020

DESCRIPTION (provided by applicant):

Ageing Labrador retrievers are often affected by a disorder causing paralysis of the vocal chords known as laryngeal paresis/paralysis (LP). This interferes with breathing, clearance of debris from the airways, swallowing, and can result in heat stroke, pneumonia and death. Diagnosis is based on examining the movement of the vocal chords under anesthesia, and by ultrasound examination of the vocal chords. Treatment is surgical, which relieves the obstruction of the airways, but predisposes the dog to pneumonia, and is expensive. Therefore, medical treatment that improved vocal cord function could provide a cheaper and safer alternative. Clinicians have observed improvement of LP after administering a drug called doxepin. However, no controlled studies have examined whether this effect is real, how frequently patients improve, how much they improve, and for how long the improvement is sustained. We will examine the effect of doxepin administered for one month to Labrador retrievers with non-critical LP and comparing it to a similarly administered placebo. We will assess the client’s impression of improvement using a standardized questionnaire as well as changes in vocal cord movement to determine whether this drug is effective in treating LP.