SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
spectral analysis or PSD graphs of recorded respiratory sounds can help identify
horses with early stage laryngeal hemiplegia as evidenced by an axial deviation of
the vocal cord/fold of the arytenoid, those horses with laryngeal collapse, and those
horses that experienced DDSP. Spectral analysis using PSD graphs of respiratory
sounds obtained during high-speed exercise in the field has the potential to help with
management decisions regarding the racing schedule of Thoroughbred racehorses
and the appropriate timing of surgical intervention if necessary.
The Cardiovascular System
This subject will be covered in depth by Dr. Reef and has recently been well
reviewed. The reader is referred to that review for its extensive list of references (see
Allen KJ, et. al, Eq Vet Edu, 2016; 28:99). HR and rhythm during exercise can be
recorded in a number of ways and constitute the mainstays of evaluation of the
cardiovascular system in poorly performing horses. In those presented for
assessment of athletic ability the focus is generally on the relationship of HR to
speed. In the latter situation any of a variety of relatively inexpensive HR meters are
used, although the rapid growth in smartphone apps which utilize Bluetooth
technology to determine and store HR data may soon make dedicated HR meters
obsolete.
There is a strong linear correlation between speed and HR when the horse is
galloping, with a definite plateau in HR being observed despite an increase in
treadmill speed when maximal HR (HR max ) has been reached. For this reason, most
evaluations of HR involve increment al tests. HR max is highest among young,
untrained horses but varies with breed and sport discipline, and tends to decrease
slowly as with age. Various parameters linking HR and speed have been proposed
as a means of facilitating comparisons between horses. The speed at which the HR
reaches 200 bpm (V 200 ) is the most popular although the HR when speed is in the
range of 10-12m/s (eg, HR V10 ) can be used. No HR-based parameters associated
with exercise testing are sacrosanct. Individuals can devise whatever makes
physiological sense in terms of the type of activity for which the horse is being
evaluated. What is essential is that the conditions of exercise be as consistent as
possible in all tests. If it is not, comparisons between horses is meaningless.
Field evaluation of horses presented for poor performance or exercise intolerance
frequently involves electrocardiography (ECG) for assessment of cardiac rhythm. A
base-apex ECG is usually obtained continuously throughout the treadmill test and
immediately afterwards. Reliable and affordable telemetry equipment is now
available and generally preferred to hard-wired systems. The placement of
electrodes and the quality of their electrical contact is the biggest source of poor
ECG recordings during exercise. The entire electrode must be in contact with the
skin which should be well wetted and/or have plenty of electrode gel applied. In
horses it may help to clip the area of electrode placement.
In clinical cases it can be difficult to determine whether or not a horse’s HR response
to exercise is abnormal or not. It helps to have a frame of reference (ie, data bank)
on which to base such an assessment. The most ideal situation exists when the
patient has results from previous tests. Most commonly, HR responses are regarded
as abnormal when the HR is unusually high at the submaximal speeds of an
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