Browsing by Author "Massie, Shannon"

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    Field-training in young two-year-old thoroughbreds: investigating cardiorespiratory adaptations and the presence of exercise induced pulmonary hemorrhage
    (2024-04-26) Massie, Shannon; Bayly, Warwick; Ohmura, Hajime; Takahashi, Yuji; Mukai, Kazutaka; Léguillette, Renaud
    Abstract Background Comparatively little is known regarding the initial cardiorespiratory response of young racehorses to training. The objectives were to compare physiological parameters before and after introductory training and determine whether young Thoroughbreds show endoscopic signs of exercise-induced pulmonary hemorrhage (EIPH). Ten Thoroughbreds (20–23 months) underwent 12-weeks of introductory training, including weekly speed sessions. Two 600 m high-speed exercise tests (HSET) were performed following weeks 4 and 12 while wearing a validated ergospirometry facemask. Peak oxygen consumption (V̇O2pk) and ventilatory parameters (tidal volume, VT; peak inspiratory and expiratory flow, PkV̇I, PkV̇E; respiratory frequency, Rf; minute ventilation, V̇E) were measured. The ventilatory equivalent of oxygen (V̇E/V̇O2) and the aerobic and anaerobic contributions to energy production were calculated. Maximal heart rate (HRmax) and HR at maximal speed (HRVmax) were determined. Post-exercise hematocrit, plasma ammonia and blood lactate were measured. Evidence of EIPH was investigated via tracheobronchoscopy post-exercise. Results were compared (paired t-test, P < 0.05). Results Horses were faster following training (P < 0.001) and V̇O2pk increased 28 ml/(kg total mass.min) (28 ± 16%; P < 0.001). Ventilatory (V̇E, P = 0.0015; Rf, P < 0.001; PkV̇I, P < 0.001; PkV̇E, P < 0.001) and cardiovascular parameters (HRmax, P = 0.03; HRVmax, P = 0.04) increased. The increase in V̇E was due to greater Rf, but not VT. V̇E/V̇O2 was lower (26 ± 3.6 vs 23 ± 3.7; P = 0.02), indicating improved ventilatory efficiency. Anaerobic contribution to total energy production increased from 15.6 ± 6.1% to 18.5 ± 6.3% (P = 0.02). Post-exercise hematocrit (P < 0.001), plasma ammonia (P = 0.03) and blood lactate (P = 0.001) increased following training. Horses showed no signs of EIPH. Conclusions Young two-year-old Thoroughbreds responded well to introductory training without developing tracheobronchoscopic evidence of EIPH.
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    High intensity, short duration pulling in heavy horses: physiological effects of competition and rapid weight change
    (2017-11-07) Greco-Otto, Persephone; Massie, Shannon; Shields, Erin; Roy, Marie-France; Pajor, Edmond; Léguillette, Renaud
    Abstract Background The Heavy Horse Pull is a competition where teams of two horses pull an increasingly heavy sled for a short distance. Similar to human wrestlers, some horses may undergo rapid weight change in order to enter a lower weight category. The objectives were to study the physiological effects of this practice as well as of the pulling competition in draft horses. Results Fifty horses were divided into light-, middle- and heavyweight categories based on their arrival weights and competed 1–3 days after. Body weight was measured upon arrival and pre-competition. Blood was sampled for chemistry and high sensitivity cardiac troponin T (hscTnT) at arrival, pre- and post-competition in 34, 26 and 20 horses, respectively. Body weight increased significantly between arrival and pre-competition for light (7.2% (Median: 62.8Kg (41.7–77.0)) and middle (8.6% (Median: 80.5Kg (62.7–90.9)) weight categories. Change in body weight was correlated (r = 0.69, p = 0.002) with competition ranking for middleweights. The ratios of weight pulled to team body weight were 2.7 (1.9–2.8), 2.6 (2.5–2.6) and 2.4 (2.2–2.5) for the lightweights, middleweights and heavyweights, respectively. Blood chemistry indicated hemoconcentration on arrival in the middleweight and lightweight horses. Hemoconcentration was not seen on arrival in some horses with marked rapid weight change. Overall, no chemistry parameter changed between pre- and post-competition. The hscTnT stayed within normal range post-competition. Conclusions While horses arrived to the event with indications of hemoconcentration, they appeared to have sufficient time to rehydrate prior to competition, and the effects of the competition were reversible within 3 h.
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    Tackling the Challenges of an Equine Metabolic Mask: Validating a Computational Approach to Simulate Airflow Using 3D Printed Models
    (2015-09-24) Massie, Shannon; Léguillette, Renaud
    Maximal aerobic capacity (VO2max) is considered the reference for determining an individual’s level of fitness. To measure VO2max, a subject must perform an incremental fitness test while wearing a facemask that samples expired gases and ventilation rates. In horses, the practicality of VO2max testing in the field is limited by mask design, specifically due to impedance of airflow. The trajectory of airflow as it enters and exits the nasal passage must therefore be fully understood in order to build a functional mask. Computational fluid dynamics (CFD) was used to model flow patterns and pressure changes at various rates in the equine nasal passage. Results were validated with experimental data obtained from a 3D printed model of a horse head. Preliminary mask designs were investigated using CFD and a current design was tested using the 3D printed model. Data was also collected on sport horses in the field.