Equine athlete

Question 1

what factors contribute to the equine athlete having a successful performance?

Answer 1

haemoglobin concentration
gas exchange
heart size
skeletal muscle properties
anaerobic capacity
biomechanics

Question 2

how fast is anaerobic compared to aerobic respiration?

Answer 2

anaerobic is much faster but not as clean (lactate produced) and less efficient

Question 3

what is VO2max?

Answer 3

the maximal aerobic metabolic rate which has a close link to performance ability
(the maximum/optimum rate at which the heart, lungs, and muscles can effectively use oxygen during exercise)

Question 4

what is the primary function of the respiratory system?

Answer 4

gas exchange

Question 5

what is the secondary function of the respiratory system?

Answer 5

humidification, filtering and warming air
thermoregulation
phonation/olfaction
acid-base regulation
pulmonary defence mechanism

Question 6

how can minute ventilation be calculated?

Answer 6

tidal volume x breaths/minute

Question 7

what is an anatomical dead space of the respiratory tract?

Answer 7

anything not contributing to gas exchange - trachea, bronchus, bronchioles, non-aerated alveoli…

Question 8

is carbon dioxide or oxygen more diffusible?

Answer 8

carbon dioxide (25x quicker)

Question 9

what does the rate of diffusion in the respiratory tract depend on?

Answer 9

pressure gradient and thickness of alveolar-capillary barrier

Question 10

how is gas transported in blood?

Answer 10

dissolved
bound to haemoglobin

Question 11

how does respiratory function change during exercise?

Answer 11

increased ventilation
increased perfusion (cardiac output)
increased diffusion
increased haemoglobin concentration

Question 12

how do horses increase their haemoglobin concentration?

Answer 12

splenic contractions

Question 13

how do exercising horses increase gas diffusion at tissues?

Answer 13

oxyhemoglobin curve shifts to the right due to hypercapnia, acidosis and hyperthermia

Question 14

what normally causes exercise induced hypoxaemia?

Answer 14

usually do to diffusion limitations

Question 15

what factors can decrease pulmonary gas exchange?

Answer 15

increased pulmonary resistance
decrease alveolar compliance
dynamic airway collapse
respiratory muscle issues
decrease cardiac output
decrease haemoglobin

Question 16

what is EIPH?

Answer 16

exercise induced pulmonary haemorrhage

Question 17

what is exercise induced pulmonary haemorrhage?

Answer 17

haemorrhage into the airways when horses are exercising at high intensity

Question 18

how is EIPH usually diagnosed?

Answer 18

post exercise endoscopy

Question 19

how does EIPH appear on post mortem?

Answer 19

blue discolouration of lungs due to haemosiderin accumulation within the damaged lung area

Question 20

where is the most common area for EIPH lesions?

Answer 20

start caudally and progress craniodorsally

Question 21

other than endoscopy post exercise, how can EIPH be diagnosed?

Answer 21

BAL for several weeks

Question 22

what are you looking to find on BAL in suspected EIPH cases?

Answer 22

haemosiderophages

Question 23

how can endoscopy be used to grade EIPH?

Answer 23

look for amount of blood in the trachea

Question 24

what is grade 1 EIPH?

Answer 24

flecks or single short stream of blood less than a quarter of the tracheal length

Question 25

what is grade 2 EIPH?

Answer 25

one continuous stream of blood extending over half the length of the trachea or multiple streams of blood covering less than one third of the tracheal surface

Question 26

what is grade 3 EIPH?

Answer 26

multiple streams of blood covering over a third of the tracheal surface

Question 27

what is grade 4 EIPH?

Answer 27

abundant blood stream in the trachea and pooling at thoracic inlet

Question 28

what is found on tracheal wash or BAL to confirm EIPH?

Answer 28

free erythrocytes and haemosiderin in macrophages (haemosiderophages)

Question 29

how long after the event can BAL be used to diagnose EIPH?

Answer 29

weeks/months

Question 30

why does EIPH occur?

Answer 30

high pulmonary vascular pressure and high inspiratory pressures

Question 31

does EIPH effect performance?

Answer 31

grade 3 and 4 are associated with performance

Question 32

does EIPH cause airway inflammation?

Answer 32

yes - neutrophils dominate initially and then macrophages take over in the more chronic stages

Question 33

how is EIPH treated?

Answer 33

rest and anti-inflammatories

Question 34

why do we want to reduce the inflammation caused by EIPH?

Answer 34

will lead to alveolar septal fibrosis that can reduce gas exchange capabilities of the alveolar as the diffuse distance increases and compliance decreases

Question 35

what medication has be shown to decrease severity of EIPH?

Answer 35

furosemide

Question 36

how does furosemide decrease severity of EIPH?

Answer 36

diuretic so will decrease the circulating blood volume and hence the circulating pressure

Question 37

why is furosemide banned in horse racing?

Answer 37

alters drug excretion rates and is a performance enhancing drug