Describe elements of the upper respiratory tract.
Nostrils - horses can only breath through their nose - cartilage maintains the nasal structure when breathing Nasal passage - maxillary bone - nasal bone - hard plate - mucous membrane over turbinates - cilia line nasal Passage to trap particals Pharynx - chamber at the back of nasal passages - where the oesophagus meets the trachea - epiglottis overlaps to protect windpipe when swallowing Trachea - aka windpipe - cilia line trachea Branches near lungs into each sac - cartilage holds it ridged and open
What are the functions of the respiratory system?
- Transfer of O2 to the RBC and body
- to inhale (O2 access) and exhale (remove CO2)
- Thermoregulation of air in the body (warm air exhaled = eat loss)
- assist in defication (increase pressure in the abdominal cavity)
- communication (snorting)
- sensory input (detect chemicals)
- trap contaminants
Describe the components of the lower respiratory tract.
- Horses lung capacity = 43,000 cm3
Bronchi - initial divide of network o branches in the lungs
Bronchioles - narrow tubes which get narrower until they become Alveoli
Alveoli important in gas exchange
What occurs when a horse inhales and exhales?
Inhalation - the rubs expand by use of intercostal muscles and diaphragm - pressure in the lungs drop - air is drawn in as a result Exhalation - passive process - cheat volume decreases Pressure in thoratic cavity increases
What is the principle of gaseous exchange?
O2 transfer from out of body into the bloodstream.
What re they main components of air?
Nitrogen -70.01%
Oxygen - 20.95%
CO2 and H2O vapour - 0.04%
What are alveoli responsible for?? What’s involved in this?
- Responsible for gaseous exchange
- deoxygenated blood passes alveoli and O2 defuses across to blood
- blood binds with haemoglobin
- CO2 diffuses into the lungs and pushed out of be body.
What gases are in exhaled air?
Nitrogen - 79.5%
Oxygen - 16.4%
CO2 and H2O vapour - 4.1%
What is the respiration rate for a resting and exercised horse?
Resting (slightly fast for young horses)
6-16brpm
Max Exercised
120brpm
- when fitness is increased the muscles involved in respiration develop
What is pulmonary capilliarisation?
- Increase in capillaries around alveoli
- increases O2 into blood
- improves with exercise
What is alveoli recruitment?
- more alveoli are used in respiration
- increases the surface area of lungs
- improves gaseous exchange
- occurs when horse gets fitter
What is the ratio of stride rate to breath when a horse is running in locomotory respiration coupling? Why?
1: 1
- ensures that locomotion doesn’t interfere with ventilation
- caps the maximum brpm at 150 and max stride rate
What anatomical changes occur when a horse runs?
- dilation of nostrils
- dilation of nasalpharynx and larynx
- straightening of the respiratory tract
Tell me…
- what the total long capacity is
- The vital capacity
- Normal capacity
- Tidal air (quiet normal) usage
- 42,000cm3
- 30,000cm3
- 24,000cm3
- 6000cm3
What is dead space and where is it found?
- found in air passages between nostrils and the alveoli
- 1 makes up about 2000cm3
- no gaseous exchange occurs here
- it’s role is to mix the air from out of the body to humidify and warm (protects the alveoli from sudden changes in temperature)
- unused alveoli also count as dead space
- at rest a late proportion aren’t used
- increased strenuous exercise will cause the use of more alveoli
- alveoli dead space reduces to near zero
What happens to the body when the fitness increases
- Increased heart rate
- pulmonary capilliarisation
- increase RBC
- slower rest rate
- better recovery rate
- less dramatic change in heart rate and respiratory rate every time the horse exercises
Describe the issues of respiratory diseases an where it stems from.
- serious and common for equine sports
- exercise use lungs 5x more so any minor issue is a big problem
- anthropogenic influences on respiratory disease eg keeping horses In stables (causes many problems).
What bacterial infections are there?
- pneumonia (Rhodococcus equi)
- strangles ( Streptococcus equi)
When do bacterial infections occur?
- Bacterial infections rely on dust in the atmosphere
- problematic for stable kept horses
- prevalent in horses that travel eg race horses.
Talk of two viral infections in horses.
Equine influenza
- dry and frequent cough at rest
- fever after 3 days incubation
- large lymph glands
Equine herpes virus I and II
- mild respiratory problems and nasal discharge
- stay dormant in body until times of stress
What is exercises induced pulmonary haemorrhage (EIPH)?
- bleeding in air passages after exercise (epistaxis) - only seen by nose bleed
- blood enters lungs due to fractures in lung capillaries
- lung function decreases due to scarring
- require endoscopic diagnosis
What is Cronin Obstructive Pulmonary Disease (COPD)?
- similar to Human athsma
- cased by allergic reaction to hay or bedding
Symptoms
- heavy reoccurnence
- airway obstruction
- Broken wind
- emphysema
- chronic bronchitis
- small airway disease
