Pleuropneumonia
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Pleuropneumonia is a severe bacterial infection in which pneumonia extends to the pleural membranes and the space surrounding the lungs. Inflammatory fluid, bacteria and fibrin accumulate in the chest, compressing lung tissue and making each breath painful. The condition is often called shipping fever because long-distance transport—particularly with the head held high—impairs airway clearance and allows normal throat bacteria to invade the lower respiratory tract.
Recent viral respiratory disease, strenuous exercise, general anaesthesia and aspiration can also weaken pulmonary defences. Early signs may be only fever, dullness and reduced appetite within days of travel. As infection advances, the horse develops rapid shallow breathing, persistent tachycardia, reluctance to move or turn, a braced stance and pain when the chest is examined. Cough can be soft because deep inspiration hurts. Fetid breath or nasal discharge suggests anaerobic infection and tissue necrosis, while ventral chest swelling can accompany a large effusion.
Pleuropneumonia is more than an ordinary cough or uncomplicated bronchitis. Sepsis, endotoxaemia and protein loss can lead to shock and laminitis. Fibrin can divide the pleural space into pockets that resist drainage; abscesses, adhesions and bronchopleural fistulae may prolong disease. Some horses later develop restrictive scarring that limits exercise.
Outcome depends strongly on how soon treatment begins, the organisms involved, the amount and character of pleural fluid and the presence of necrotic lung. Horses recognised at the first post-transport fever have a much better chance than those presented after days of respiratory distress. Recovery can take months even when infection is controlled, and return to athletic work requires objective reassessment rather than a rapid restart after the temperature normalises.
Long-distance transport is a classic risk because prolonged head elevation impairs airway clearance, allowing bacteria from the throat to invade lung and pleural space. Pleural fluid restricts breathing and can organise into loculated pockets or a fibrinous rind. Weight loss, reluctance to move and shallow painful breaths may persist after fever falls, reflecting unresolved thoracic disease.
Screening & Early Detection
Any horse with fever, depression or rapid breathing after long-distance transport should be examined promptly. Owners should record journey duration, head restraint, recent respiratory infection, medication and the first abnormal temperature. Daily temperature checks for several days after major travel can identify disease before pleural pain and effusion become obvious.
Veterinary examination assesses respiratory pattern, chest pain, lung and heart sounds, mucous membranes and laminitis risk. Thoracic ultrasound is central for locating pleural fluid, consolidated lung, fibrin strands, abscesses and safe drainage sites. Radiographs add information about deeper lung when the horse is stable enough. Blood counts, fibrinogen or serum amyloid A, protein, kidney values and lactate help assess systemic severity.
Tracheobronchial aspirate and pleural fluid should be collected for cytology, Gram stain and both aerobic and anaerobic culture with susceptibility testing. Thoracocentesis is diagnostic as well as therapeutic. Repeated ultrasound maps fluid pockets and response to drainage. A normal-looking nasal discharge or quiet cough does not exclude serious chest infection; persistent post-travel fever and tachypnoea justify imaging before respiratory distress develops.
Treatment & Management
Treatment is aggressive and prolonged. Broad-spectrum antimicrobial therapy is started promptly against likely aerobic and anaerobic organisms, then adjusted to culture results and clinical response. Courses commonly last weeks and sometimes months because devitalised lung and pleural pockets are difficult to sterilise. Intravenous fluids, analgesia, anti-inflammatory care, oxygen and nutritional support are tailored to sepsis, pain and respiratory function.
Septic or compressive pleural fluid must be drained through thoracocentesis or indwelling chest tubes. Bilateral drainage may be needed, and ultrasound guides placement away from the heart and diaphragm. Thick fibrinous material can require repeated lavage, additional drains, intrapleural fibrinolytic treatment or surgical debridement. Drainage is controlled because rapid removal of a large volume can destabilise circulation.
Horses are monitored for laminitis, thrombophlebitis, antimicrobial complications, protein loss, pneumothorax and recurrent fluid accumulation. Distal-limb cryotherapy may be used for laminitis prevention in high-risk systemic inflammation. Travel prevention includes good health before transport, ventilation, hydration, rest breaks where feasible and allowing the head to lower regularly so airway secretions clear. After recovery, exercise resumes slowly following clinical and imaging reassessment. Prognosis is variable: early, drainable infection can resolve well, whereas fetid fluid, extensive necrosis, persistent sepsis and chronic adhesions are guarded.
Breeds or species affected
Akhal-Teke
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Anglo-Arabian
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Arabian
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Barb
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Caspian
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Kathiawari
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Marwari
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Shagya Arabian
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Thoroughbred
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American Quarter Horse
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American Paint Horse
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Appaloosa
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Australian Stock Horse
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Brumby
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Waler
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Morgan
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Standardbred
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American Saddlebred
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Tennessee Walking Horse
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Missouri Fox Trotter
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Rocky Mountain Horse
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Peruvian Paso
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Criollo
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Mustang
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Canadian Horse
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Andalusian
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Lusitano
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Lipizzaner
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Cleveland Bay
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Württemberger
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Zangersheide
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Knabstrupper
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Orlov Trotter
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Camargue
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Icelandic Horse
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Pony of the Americas
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Quarter Pony
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Miniature Horse
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Norwegian Fjord
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Haflinger
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Gypsy Cob
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Irish Draught
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Welsh Pony and Cob
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Connemara Pony
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New Forest Pony
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Dartmoor Pony
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Exmoor Pony
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Shetland Pony
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Highland Pony
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Fell Pony
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Dales Pony
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Australian Pony
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Finnhorse
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Black Forest Horse
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