|
|
|
| The Horse’s Specialised Respiratory System |
Disclaimer
|
|
There are a number of respiratory diseases and airway conditions that affect horses.
Respiratory disease is second only to lameness as a major cause of downtime from training in racing and performance horses, and is responsible for over 20% of all lost training days. In Australia, viral diseases account for over 50% of respiratory infections. Up to 57% of horses with reduced performance capacity have underlying airway and lung disease.
|
|
|
Features of the horse's respiratory system
Top
The respiratory system of the horse is well adapted to athletic exercise, with unrestricted upper airway diameters, and a large lung capacity afforded by 18 ribs. These combine to enable air intakes of up to 1800 litres per minute in a galloping horse. 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 at the gallop.
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.
|
Diagnosis of respiratory problems
Top
A range of diagnostic methods is available to vets to allow diagnosis and recommendation of specific treatments for a large variety of respiratory related problems. These 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, and ultrasound.
|
Checklist of common airway conditions
Top
| 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 |
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Article courtesy of Dr John Kohnke from ‘Health Care and problems of Horses, 9th edition’ published by Virbac-Vetsearch.
Dr John Kohnke has over 20 years of experience in the health care and management of horses. He is well known for his ability to give sound, practical and up-to-date advice, which is sought by trainers and horse owners worldwide. As Technical Director of Vetsearch for 20 years, John had an opportunity to pursue research in equine nutrition, parasite control, lameness and respiratory problems.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
