Discussion

Kelly, P.G., Reardon, R.J.M. and Pollock, P.J.
University of Glasgow, Weipers Centre Equine Hospital, School
of Veterinary Medicine, 464 Bearsden Road, Glasgow G61 1QH,
UK. Email: p.kelly.1@research.gla.ac.uk
Aims: 1) To describe the diagnosis, treatment and outcome for a
group of horses with cricotracheal ligament collapse (CTLC)
during exercise; and 2) to describe a surgical technique for the
condition. Methods: The records of 600 cases presented for
endoscopic examination of the upper respiratory tract (URT) at
exercise, because of poor performance or abnormal respiratory
noise, were reviewed. Cases of CTLC, defined as: circumferential
collapse of the cricotracheal ligament, were identified. The records
for these cases, including medical history and endoscopic findings
were reviewed. Results: Seven horses with CTLC were identified
all of which underwent repeat endoscopic examination at
exercise. All were Thoroughbred racehorses, 5 were 2 years old
and in early training, and 2 were mature horses in full work.
Multiple abnormalities of the URT were identified as well as CTLC
in all five 2-year-old horses. In all of these 5 horses CTLC resolved
following conservative management. In the 2 mature horses no
concurrent respiratory abnormalities were identified and CTLC did
not resolve following conservative management. For these cases,
surgical reduction of the cricotracheal space and imbrication of
the cricotracheal ligament resulted in resolution of clinical signs
of CTLC. Conclusions: In this population CTLC was found to be
a rare cause of dynamic obstruction of the URT. Resolution of the
condition may occur, particularly in young horses in early training
presenting with concurrent abnormalities of the upper airway. For
horses with persistent CTLC, surgical reduction of the
cricotracheal space and imbrication of the cricotracheal ligament
was curative. Practical significance: Cricotracheal ligament
collapse should be considered as a differential diagnosis when
investigating dynamic obstruction of the URT. Conservative
treatment is initially recommended in all cases; however, where
CTLC is identified during serial examination and no other
pathology exists, surgical management may be indicated and can
be curative.