Getting the correct diagnosis in cases of upper airway disease

Accurate diagnosis in cases of upper respiratory tract obstruction is of paramount importance for the success of any subsequent treatment. As with all branches of veterinary medicine much information can be gleaned from the history and clinical examination, which allows more targeted use of advanced diagnostics.

History

Accurate history will often give clues as to where the upper respiratory tract problems are localised. The history is usually of upper respiratory tract noise or horses are failing to perform to expectations or a combination of these 2 complaints. The nature of the reported noise is important. If the noise is only exhibited intermittently it may be worth warning the owner that the noise may not be heard at the time of veterinary inspection. Horses that only exercise for a limited time, such as showjumpers or dressage horses, may be more tolerant of upper respiratory tract obstruction therefore owners usually only complain of upper respiratory tract noise rather than poor performance. The characteristics of racehorses exhibiting respiratory noise can be helpful, gurgling noises that occur halfway through a race coupled with a drop in performance may indicate a palatal problem. Inspiratory whistling noises may or may not be related to recurrent laryngeal neuropathy. A recent study showed the traditional approach of performing a ventriculocordectomy or ‘Hobday’ would have been appropriate for treatment for horses making a ‘whistling’ or ‘roaring’ noise in only 7% of cases [1].

Clinical examination

Palpation of the larynx is a very useful tool, but does require practice. Palpation is useful to evaluate the difference in prominence of the muscular process between the left and right sides in recurrent laryngeal neuropathy. Or for cases of fourth branchial arch defect (4-BAD), the gap between the thyroid and cricoid cartilages can be felt. Auscultation of the heart and lungs with a stethoscope is advisable especially if an exercise test is subsequently to be performed. […]