Moving horses interstate and internationally is a common occurrence in the equine industry. A disease associated with long distance movement is called Travel Sickness, also known as Shipping Fever or Pleuropneumonia. A respiratory disease of the lung tissue and pleural cavity (the space adjacent to the lungs in the chest), Pleuropneumonia has been a well recognised condition since the early 20th Century.
Pleuropneumonia became a major issue during overland and sea transportation of army remount horses during the Boer and First World Wars, and caused three times as many fatalities as all other causes combined. The disease was initially thought to be a highly contagious condition exacerbated by crowded conditions and poor ventilation.