ISSN 2398-2977      

Lung: pneumonia - bacterial


Pulmonary abscessation and bacterial pneumonia


  • Variable but can include:
    • Dyspnea.
    • Tachypnea.
    • Increased respiratory effort.
    • Pyrexia.
    • Inappetance.
    • Lethargy.
    • Coughing.
    • Thoracic pain.
    • Submandibular lymphadenopathy.
    • Purulent nasal discharge.
    • Foul smelling breath and nasal discharge.
    • Standing with elbows abducted
    • Other signs consistent with endotoxemia.


Predisposing factors
  • Viral infection, eg EHV-1, EIV:
    • May impair immune defenses against bacteria invasion of lower airways.
  • Long distance transportation:
    • Prolonged periods of time with the horse's head tied up precludes them being able to lower their head to clear the airways of dust and debris.
  • Inflammatory diseases of the lower airways (mild to moderate equine asthma (MMEA), recurrent airway obstruction).
  • Esophageal impaction leading to aspiration:
    • Feed and saliva can be aspirated into the lungs during esophageal impaction.
Most common causative organisms


Increasing respiratory depth by occluding the nares or the use of a rebreathing bag will increase lung noise thus aiding detection of abnormalities.

Differential diagnosis
  • Viral respiratory infection (EHV-1, EIV).
  • Inflammatory airway disease.
  • Recurrent airway disease.
  • Pulmonary neoplasia.



  • Pulmonary abscessation and severe bacterial pneumonia are associated with a high mortality rate necessitating early diagnosis and aggressive treatment.
Print off the Owner factsheet on Respiratory problems in your horse to give to your clients.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Toombs-Ruane L J, Riley C B et al (2015) Antimicrobial susceptibilities of aerobic isolates from respiratory samples of young New Zealand horses. J Vet Intern Med 29 (6), 1700-1706  PubMed.
  • Ferrucci F, Zucca E, Croci C, Di Fabio V, Martino P A & Ferro E (2008) Bacterial pneumonia and pleuropneumonia in sport horses: 17 cases (2001-2003). Equine Vet Educ 20 (10), 526-531 VetMedResource.
  • Wilkins P A (2003) Lower airway disease of the adult horseVet Clin Equine 19 (1), 101-121 PubMed.
  • Bertone J J (1997) Antimicrobial therapy for respiratory disease. Vet Clin North Am Equine Pract 13 (3), 501-517 PubMed.
  • Oikawa M, Takagi S, Anzai R, Yoshikawa H & Yoshikawa T (1995) Pathology of equine respiratory disease occurring in association with transport. J Comp Pathol 113 (1), 29-43 PubMed.
  • Dixon P M, Railton, D I & McGorum B C (1995) Equine pulmonary disease - a case control study of 300 referred cases. Part 1 - Examination techniques, diagnostic criteria and diagnosis. Equine Vet J 27 (6), 416-421 PubMed.

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