264


EQUINE VETERINARY EDUCATION / AE / MAY 2018


There was agreement between subjective lameness


findings and objective gait analysis. All horses had some degree of lameness in a straight line. All horses had forelimb lameness, of which eight limbs were grade 1 lame, five limbs were grade 2 lame, and seven limbs were grade 3 lame. Two horses had bilateral forelimb lameness of grade 1 on each, and one horse had bilateral forelimb lameness of grade 1 on one and grade 2 on the other limb. All horses had hindlimb lameness, of which three limbs were grade 1 lame, eight limbs were grade 2 lame and seven limbs were grade 3 lame. One horse was bilaterally hindlimb lame, with one limb grade 1 and the other limb grade 2. The worst lameness in six horses was a grade 2, and in 11 horses a grade 3. Seven horses had the most severe lameness in the hind end, four horses had the most severe lameness in the forelimb, and six horses had a front limb and a hind limb that were of the same lameness grade (3 horses grade 2 lame on both; 3 horses grade 3 lame on both). There was no historical suggestion of upper airway


abnormalities reported by the trainers (i.e. exercise intolerance or upper respiratory noise). Fourteen horses had dynamic endoscopy performed, but two horses resisted exercising with the endoscope and this was removed before completion of the test. In two horses, dynamic endoscopy was not attempted because the trainer did not consider it safe due to the horses’ character. Three horses developed mild unilateral epistaxis during placement of the endoscope that resolved spontaneously during or shortly after exercise. Four horses had dynamic airway obstruction and one had static obstruction. Three horses showed dynamic laryngeal collapse (dynamic Grade B) secondary to left recurrent laryngeal neuropathy during maximal exercise and one horse showed dynamic pharyngeal collapse (rostral billowing of the soft palate). One horse showed a mild static obstruction due to nasopharyngeal cicatrix. Results of BALF and tracheal mucus scores are displayed


in Table 1. There was no blood detected in the trachea after the exercise test in any case or evidence of EIPH in BALF. Results of echocardiographic measurements are described in Supplementary Item 2. In one horse, mild mitral regurgitation was diagnosed (horse with systolic murmur) and in all other cases no significant cardiac disease was detected. Summary statistics for HR, RR, temperature, PCV, CK and


lactate are described in Table 2. The heart rate and lactate concentration increased during exercise, as expected, and were highest after sets of sliding stops. CK was higher 4–6h after exercise than at rest in all horses. In one horse, the resting CK activity was high (947 l/L; reference range 73–450 l/L) and increased to 6433 l/L after exercise evidencing the present of a myopathy. This horse subsequently tested


TABLE 1: Tracheal mucus score and cytology of bronchoalveolar lavage fluid obtained after exercise tests in reining horses


Tracheal mucus (score) Neutrophils (%) Eosinophils (%) Mast cells (%)


Macrophages (%) Lymphocytes (%)


Median 0


4 3 0


57.5 35.5


Range 0–3


2–16 1–7 0–5


32–76 9–65


positive for GYS1 gene mutation and PSSM was diagnosed. Supplementary Item 3 shows the linear progression of HR in one horse during the exercise test and the immediate pre- and post-exercise periods. One horse had one ventricular premature complex (VPC) immediately after galloping, one horse had one ventricular premature complex immediately after a stop (Fig 1), one horse had two single SVPCs before exercise and one horse had a total of 15 single SVPCs during periods of fast HR deceleration after stops. Six horses had intermittent second degree AV block at rest and six intermittent sinus arrhythmias at rest or immediately after exercise. Five horses had sinus pauses during fast HR deceleration. There was an increase in the baseline artefact during stops (Fig 1) and spins (Fig 2) in all instances but the R- R interval and QRS morphology was identifiable and all recordings were considered diagnostic. Sweat response was assessed as full in five cases, moderate in nine cases and mild in two cases.


Discussion


The SET protocol was completed without significant complications in all horses but one horse was removed from the study due to the severe degree of lameness before the ridden portion was performed. The dynamic upper airway endoscopy was the only part not tolerated by all horses. Horses in this study were a distinct subset that had been donated to the University Equestrian Team most commonly for reasons related to musculoskeletal disease or behaviour and this explains the prevalence of lameness. It is common, however, that athletes compete with musculoskeletal problems managed with various therapies. Lameness was detected by a specialist and using body mounted inertial sensor but was unlikely to be detectable by the untrained eye in many cases. With the exception of one horse, horses were considered to be able to exercise without their welfare being compromised and lameness was not obvious during ridden work. The results of the lameness evaluation provided information for monitoring to identify areas of concern that may need to be further evaluated and treated.


TABLE 2: Heart rate (HR), respiratory rate (RR), lactate, packed cell volume (PCV) and creatine kinase (CK) of reining horses during and after an exercise test


Mean


HR/lactate rest (bpm/mmol/L) HR walk (bpm) HR trot (bpm) HR lope (bpm)


HR/lactate gallop (bpm/mmol/L) HR/lactate spins (bpm/mmol/L) HR/lactate stops (bpm/mmol/L) HR 10 min after exercise (bpm) RR rest (breaths/min)


RR after exercise (breaths/min) PCV rest (%)


PCV after exercise (%) CK rest (iu/L) CK 4–6 h (iu/L)


CK 4–6h – CK rest (iu/L)


32/0.54 62


103 131


162/1.8 104/1.1 176/2.7 47 20 64


36.3 40.5 211


174* 37*


s.d.


2.8/0.1 7.6 14 11


18/0.8 12/0.5 14/1.5 7


11.5 6


3.3 5


196


124–6433# 0–5486#


bpm = beats/min. The values marked with * correspond to median and # to ranges.


© 2017 EVJ Ltd


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