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

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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

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7066

17 17

Perc

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Moderate Severe Normal

Perc

enta

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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

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20

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7058

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6659

Round Hay Bales vs Square Hay Bales

Round B...

Perc

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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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