Equis ISSN 2398-2977

Lung: pneumonia - neonatal bacterial

Contributor(s): Kate Hepworth-Warren, Timothy Mair, Wendy E Vaala


  • Respiratory tract is one of the main routes of entry for bacteria into the body. As such, pneumonia is one of the most common infectious diseases in the neonatal foal.
  • The majority of pneumonia in neonatal foals is secondary to sepsis or bacteria entry via another site in the body, ie umbilicus, gastrointestinal trace).
  • Heavy economic losses in the horse breeding industry can result from pneumonia. This can be due to fatalities, growth retardation and expense of treatment.
  • Cause: predisposing factors include failure of passive transfer of immunoglobulins   Foal: failure of passive transfer (IgG)  , other forms of immunodeficiency, intrauterine infections, prematurity   Reproduction: prematurity / dysmaturity  , conditions which cause recumbency and inhalation of foreign material   Respiratory: meconium aspiration  .
  • Mixed bacterial infections and pneumonia associated with septicemia are very common.
  • Signs: lethargy, decreased nursing, increased respiratory effort, mucopurulent nasal discharge, coughing, tachypnea, fever, dyspnea, weakness.
  • Diagnosis: history, clinical signs, auscultation, radiography.
  • Treatment: broad specturm or targeted antimicrobial therapy; good quality nursing and support are essential adjuncts to therapy.
  • Prognosis: guarded to poor.



Predisposing factors



  • Prematurity, dysmaturity or neonatal maladjustment syndrome   Foal: neonatal maladjustment syndrome  can result in a deficiency of surfactant in the lungs   →   development of pneumonia.
  • Meconium aspiration   Respiratory: meconium aspiration  .
  • Aspiration of food or milk due to, eg cleft palate   Hard / soft palate: cleft  or due to dysphagia associated with prematurity, peripartum asphyxia, HIE (hypoxic ischemic encephalopathy), or general mechanisms due to sepsis.


  • Most commonly, failure of passive transfer of colostral immunoglobulins   →   development of septicemia   →   pneumonia.
  • Immunodeficiency, such as SCID in Arabian foals, decreases defenses against bacterial invasion.
  • Aspiration of meconium in utero, or milk or saliva after parturition, can lead to aspiration pneumonia   Lung: pneumonia - aspiration  .
  • Meconium aspiration does not directly cause bacterial pneumonia, but can predispose the lungs to infection with other pathogens.
  • In cases of neonatal maladjustment syndrome   Foal: neonatal maladjustment syndrome  , prematurity and dysmaturity, a deficiency of surfactant and dysphagia can lead to pneumonia.


  • Signs of septicemia and pneumonia can be evident shortly after parturition.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Fultz L, Giguere S, Berghaus L J et al (2014) Pulmonary pharmacokinetics of desfuroylceftiofur acetamide after nebulisation or intramuscular administration of ceftiofur sodium to weanling foals. Equine Vet J 47 (4), 473-377 PubMed.
  • Holcombe S J, Hurcombe S D et al (2012) Dysphagia associated with presumed pharyngeal dysfunction in 16 neonatal foals. Equine Vet J Suppl 41, 104-109 PubMed.
  • Johnson P J, Messer N T & DeClue A E (2012) Neonatal respiratory distress and sepsis in the premature foal: Challenges with diagnosis and management. Equine Vet Educ 24 (9), 453-458 VetMedResource.
  • Palmer J E (2005) Ventilatory support of the critically ill foal. Vet Clin Equine 21 (2), 457-486 PubMed.
  • Stratton-Phelps M, Wilson W D & Gardner I A (2000) Risk of adverse effects in pneumonic foals treated with erythromycin versus other antibiotics - 143 cases (1986-1996). JAVMA 217 (1), 68-73 PubMed.
  • Perron Lepage M F et al (1999) A case of interstitial pneumonia associated with Pneumocystic carinii in a foal. Vet Pathol 36 (6), 621-624 PubMed.
  • Anzai T et al (1997) Comparison of tracheal aspiration with other tests for diagnosis of Rhodococcus equi pneumonia in foals. Vet Microbiol 56 (3-4), 335-345 PubMed.
  • Raidal S L (1996) The incidence and consequences of failure of passive transfer of immunity on a Thoroughbred breeding farm. Aust Vet J 73 (6), 201-206 PubMed.
  • Palmer J E (1994) Ventilatory support of the neonatal foal. Vet Clin North Am Equine Pract 10 (1), 167-185 PubMed.
  • Ewing P J et al (1994) Pneumocystis carinii pneumonia in foals. JAVMA 204 (6), 929-933 PubMed.
  • Tanaka S et al (1994) Pneumocystis carinii pneumonia in a Thoroughbred foal. J Clin Microbiol 32 (1), 213-216 PubMed.
  • Lakritz J et al (1993) Bronchointerstitial pneumonia and respiratory distress in young horses - clinical, clinicopathologic, radiographic, and pathological findings in 23 cases (1984-1989). J Vet Intern Med (5), 277-288 PubMed.
  • Reimer J M et al (1989) Ultrasonography as a diagnostic aid in horses with anaerobic bacterial pleuropneumonia and/or pulmonary abscessation - 27 cases (1984-1986). JAVMA 194 (2), 278-282 PubMed.
  • Rose R J et al (1979) Intranasal oxygen in the treatment of staphylococcal pneumonia in a foal. Vet Rec 104 (19), 437 PubMed.

Other sources of information

  • Wilson W D (1997) Foal Pneumonia. In: Current Therapy in Equine Medicine. 4. Ed: Robinson N E. W B Saunders Co, USA. pp 609.