Powering Performance Horses: Keeping Equine Athletes in Top Form
Renaud LéguilletteCalgary Chair in Equine Sports MedicineAssociate Professor, Faculty of Veterinary Medicine (UCVM)
Equine Sports Medicine:What do we know about horse athletes
Welcome
Webinar series by University of Calgary scholars Information presented is a summary of the
scholars’ research
Renaud Léguillette, UCVMTraining
DVM: Paris, France, Maisons-Alfort Vet. School (ENVA)
Clinical training/ specialty boards: University of Montreal (internship/ residency: Equine internal medicine)
Equine Sports Medicine and Rehabilitation specialty boards (new college)
MSc: equine asthma
PhD: McGill University, Meakins-Christie Laboratories on bronchial smooth muscle in human asthma
Presentation objectives
Introduction to the incredible exercise physiology of horse athletes: How do they do it?
What are the limiting factors?
What can go wrong: Throat, lungs, heart
How do we treat and help these horses?
All sorts of efforts: Fast, Up, Sideways, Pulling …
How do these equine athletes do it?
Incredibly efficient in their movements
Can take-up a lot of oxygen (O2) from the air (respiratory)
And can deliver O2 to the muscles (cardiac)
Self “blood doping” system (O2 transportation)
Incredibly tolerant to running anaerobic (without O2)
Horse locomotor apparatus: Built to run!
Muscle mass is UP: Less inertia/ Less energy lost moving the mass
Equine limb Human limb
Pulleys/ Spring system of the tendons and ligaments: Passive accumulation of energy in extension returned in flexion
Horse locomotor apparatus: Built to run!
Pulleys/ Spring system of the tendons and ligaments: Passive accumulation of energy in extension returned in flexion
Horse locomotor apparatus: Built to run!
Incredible Respiratory System
35-50 /min 100-180 /min100-200 L/min >1500L/min
Max:Fig. by Shannon Massie
Respiratory: Giant lungs
Modified from: Encyclopedie du Cheval, 1903
Incredible Cardiac System
70 bpm 35 bpm
220-age bpm 220-240 bpm20-30 L/min 250-450 L/min
Resting:
Max:
Self “Blood Doping”
Spleen contraction: “Self blood dopping”12L of blood with 80% red blood cells (RBCs)
• Hematocrit (% RBCs) rest: 32%• Hematocrit (% RBCs) exercise: 65%
Results: Incredible O2 consumption
VO2max: Per Kg Average person Average horse
40-50 ml/kg/min >150 ml/kg/min
Elite human athlete ~80ml/kg/min Racehorse >200ml/kg/min Human record 97.5ml/kg/min (18 yo Norwegian cyclist in 2012)
What is the limiting factor?The respiratory system!
Horses are hypoxic at maximal speed:“Diffusion limitation”:
• Very low PaO2:70 mmHg (vs 92-99 mmHg at rest)• Blood “flows too quickly” in the lungs
Horses are hypercapneic at maximal speed:“Ventilation limitation”:
• Increased PaCO2: 50+ mmHg (vs 44 mmHg at rest)• Locomotory:respiratory coupling.
Resistance to airflow
‘Bottleneck’:Nose/ Throat
‘Soccer field’:Lungs/ Alveoli
Upper AirwaysLower Airways
‘Pipe’:Trachea
Turbulence:- Increased velocity- Decreased diameter
Respiratory: Upper airways project
Exhalation Max/Running Rest
Exhalation Max/Running InhalationFlow
Wei
ghte
d Ve
loci
tyRespiratory: Upper airways project
Respiratory: Upper airways project
What can go wrong?
Upper airways: Throat
Lower airways: Lung
Cardiac
What can go wrong?
Upper airways: Throat
We assess the upper airways with a camera: Endoscopy
Static obstructions: Endoscopy at rest
Challenge of the dynamic obstructions: • Only happen during exercise when high flows• Completely normal at rest
What can go wrong?Upper Airways
Endoscopy during exercise?
Older option:High speed treadmill
Dynamic upper airways endoscopy
DRS: Dynamic Respiratory Scope:• First in Canada 5 years ago• Contribution from Equine Foundation of Canada (Eldon Bienert)
DRS: In the field, for all disciplines
Dynamic obstructions
DRS movie:• Dorsal displacement of soft palate• Laryngeal hemiplegia• Axial deviation of arytenoepiglotic folds• Retroversion of epiglottis• Pharyngeal collapse
How do we help with these problems?
Often a throat surgery (often general anesthesia)
Now options of laser surgeries (standing sedation)
Management (stress, bits, other problems)
What can go wrong?
Upper airways: Throat
Lower airways: Lung
What can go wrong?Lungs: “Asthma”
“Equine Asthma”Two non-infectious Diseases
Mild Severe
Inflammatory Airway Disease “Heaves”(IAD) Recurrent Airway Obstruction(RAO)
Coughing Labored breathing AT RESTMucus/ nasal discharge CoughingDecreased performance Severe: Not ridable
Horse asthma: Is it common in AB?
Moderate Airway Inflammation Severe Airway Inflammation Normal0
10
20
30
40
50
60
7066
17 17
Perc
enta
ge
Moderate Severe Normal
Perc
enta
ge
66%
17% 17%
Equine screening tools: Questionnaire
Horse owners are very reliable to detect clinical signs
Questionnaires are focusing on clinical signs at rest
To detect Severe or moderate Inflammation: Did the horse cough in the past? (sensitivity = 0.97)
COUGH is the key respiratory sign
Equine screening tools: COUGH
Questionnaires are helpful to identify respiratory problems but not good to differentiate Moderate vs Severe Inflammation.
How to diagnose lung inflammation/ asthma?
Bronchoalveolar lavage (BAL)
How to diagnose lung inflammation/ asthma?
“Cellular phenotypes” in horse asthma
Equine mild asthma:Immune system response
Cytokines (Immune mediators) identified in BAL: Difference between mast cells and neutrophils mild asthma horses
Bronchoprovocation tests:Histamine challenge to measure the dose of histamine inducing bronchoconstriction
How to document lung asthma in research?
0
20
40
60
Day 0 Day 7 Day 15
Rea
ctiv
ity (%
mg/
ml)
*** *
Flow
Pressure
Amplification AnalysisPrinting Record
How to treat lung inflammation/asthma?
The key is NOT to treat asthma
But to PREVENT exposure to dust/ allergens
Round hay bales - “Digging” problem
Round hay bales:2 times more likely to have severe asthma
RAO IAD Normal0
10
20
30
40
50
60
7058
344142
6659
Round Hay Bales vs Square Hay Bales
Round B...
Perc
enta
ge
How to prevent lung inflammation/asthma?
How to treat lung inflammation/asthma?
Treatments to decrease inflammation
Treatments to “open” the bronchi and decrease mucus
Systemic corticosteroids: Dexamethasone
Most effective to less effective:• Dexamethasone:
• high doses, then taper down, but keep for LONG term• Isoflupredone (Predef 2X):
• IM injections• Prednisolone:
• NOT prednisone (poor bioavailability)
Inhaled corticosteroids: Devices
Discontinued:Lower efficiency
Effects of inhaled steroids on airway hypersensitivity
Fluticasone: BlackDexamethasone: White
What can go wrong?
Upper airways: Throat
Lower airways: Lung• Asthma• “Bleeders” EIPH
“Bleeders”:Exercise induced pulmonary hemorrhage (EIPH)
What is it?• Horses can bleed from their lungs with high intensity exercise.• Common in horses racing at high speeds (up to 80%)• Often paired with poor athletic performance
How does it work? Not entirely sure• Transmural stress and capillary walls ruptures
Pulmonary Arteryhypertension
Aveoli “vacuum”
Hemosiderophages
BAL: Anytime (days) post race
How do you diagnose EIPH?
How do you diagnose EIPH?
Endoscopy: 30+ mins post exercise
Study results: Barrel Racers: EIPH
170 endoscopies >45% EIPH in tested Barrel racers Only 5/ 77 EIPH had blood at nostrils:
Mostly internal bleeding
How can we treat EIPH?
No cure: Preventive measures. Active research field! Treat lung inflammation Decrease blood pressure Decrease “vacuum” in lungs
What can go wrong?
Upper airways: Throat
Lower airways: Lung
Cardiac
Electrocardiograms (ECG) during exercise in horses
Electrical activity of the heart No studies published on racing ECGs: Challenging technique
What can go wrong?Arrhythmias during exercise
Ventricular premature contraction (VPC) An early beat originating from the ventricle
Chuckwagons study
13 teams 148 horses 377 ECGs
Same prevalence as other disciplines
VPCs are rare during racing
Chuckwagons study
Can we detect and prevent cardiac problems?
Goal: Find a marker of cardiac damage BEFORE racing
Validation of a new high sensitivity troponin assay Collaboration with Dr. Seiden-Long (CLS)
NormalRacehorses
Test to diagnose cardiac problem post event High sensitivity troponin after competition or clinical signs 3-6hrs post is the best blood sampling time No correlation with age
What did we learn?
Horses have incredible adaptations to run. Their limiting factor is the respiratory system
Any nose or throat problem will affect airflow and athletic capacity
Many horses have mild asthma, a few have severe asthma
Many high level horses have lung bleeding
Severe cardiac electrical problems are very rare
We have validated markers of cardiac muscle damage
Where do we go from now?
Technologies in the field. Field studies
We needed a portable system to measure VO2max and just got it developed!
Critical to assess fitness Critical to develop better & safer training protocols Critical to test training options like water treadmill
We (and others) are working on the prevention of EIPH
Technology
Dr. Bayly’s mask/collaboration:
Thank you
Horse owners for volunteering their horses in our field studies.
Calgary Stampede Events organizers Linda Atkinson
Students and trainees:• Summer students• Graduate students• Resident/ Interns
Upcoming webinars
Our Brains and Fatigue, October 4, 12-1 p.m. MST No Pain No Gain? The Sociology of Sports, October
6, 12-1 p.m. MST The Race to Prevent Running Injuries, October 11,
12-1 p.m. MST Inside the Mind of an Olympian, October 13, 12-1
p.m. MST Knocking Out Concussions in Sports, October 20,
10-11 a.m. MST
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