The Horse Respiratory System

Horse Respiratory System & Breathing

The horse respiratory system and good breathing function is fundamental to good horse health.

No matter how fit your horse’s muscles are or how well you feed him, if he can’t breathe properly then he won’t be good for much at all.

The horse respiratory system is well adapted to athletic exercise, with unrestricted upper airway diameters and a huge lung capacity within 18 ribs.

These features combine to enable an air intake of up to 1800 litres per minute in a galloping horse.

Features of the horse respiratory system

1. Buccal cavity
2. Nasal Cavity (open to pharynx)
3. Inferior maxillary sinus
4. Superior maxillary sinus
5. Frontal sinuses
6. Guttural pouch

7. Pharynx
8. Trachea
9. Bronchus
10. Alveolus
11. Lungs
12. Larynx

A. Trachea
B. Cartilage
C. Vocal cord
D. Epiglottis

The horses respiratory system
When your horse is at full gallop, volumes of up to 300 litres of blood are pumped at high pressure through small lung capillaries surrounding 10 million air sacs to take up and deliver over 70 litres of oxygen per minute to the working muscles.

As a result, any restriction in upper airway diameter, obstruction of the airways, diseases or stress related conditions that reduce efficiency of oxygen uptake from the air sacs, can have a great influence on athletic capacity.

The large lung surface and high blood flow rates also provide the additional function of heat loss during and after exercise, with up to 20% of the muscle heat generated during exercise being exchanged across the lung surface to supplement sweating and other skin surface heat loss mechanisms.

The respiratory system is continually challenged by a large amount of foreign material, including viruses, bacteria and fungi inhaled in air from track and arena surfaces during exercise, or from dusty bedding, feed and stable environments.

Diagnosing respiratory problems:

A range of diagnostic methods are available to vets to allow diagnosis and recommendation of specific treatments for a large variety of respiratory related problems.

These respiratory diagnostics include :

  • Fibreoptic scopes to visually examine and collect samples from the throat and windpipe.
  • Airway swabs to identify infections
  • Bronchiolar lavage (BAL) or ‘lung washes’ to examine lung cell types
  • Chest X-rays
  • Ultrasound scans

Common Equine Respiratory Conditions include …

Upper Respiratory Tract

  • Pharynx (Throat Area) Equine Herpes Virus (‘Stable Virus’)
  • Pharyngeal Lymphoid Hyperplasia (PLH)
  • Epiglottic Entrapment (EE)
  • Dorsal Displacement of the Soft Palate (DDSP)
  • Larynx Roaring (Left Laryngeal Hemiplegia)

Lower Respiratory Tract

  • Trachea Reactive Airway Disease (RAD)
  • Lungs Equine Herpes Virus (‘Stable Virus’ – spread to lungs)
  • Bleeding (EIPH) Bacterial Pneumonia/Pleuropneumonia
  • Reactive Lower Airway Disease (RAD)
  • Acute Respiratory Syndrome – Hendra Virus