Equine bacterial pleuropneumonia (Proceedings) - Veterinary Healthcare
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Equine bacterial pleuropneumonia (Proceedings)


CVC IN SAN DIEGO PROCEEDINGS


Definitions

• Bacterial pneumonia = inflammation of the lung caused by bacterial colonization and multiplication

• Lung Abscess – localized, encapsulated regions of pulmonary necrosis, debris & exudate

Pleuropneumonia

• Microbial colonization of lung

• Development of pneumonia lung abscesses

• Extension to visceral pleura & pleural space

• Development of "parapneumonic effusion"

Economic Importance

o Not studied analytically

o Medical care

o Loss of potential income

o Extensive recuperation period

o Diminished performance

o Mortality

Pathophysiology

Bacterial pneumonia

• Occurs when pulmonary defense mechanisms are:

• Compromised

• Overwhelmed

Pulmonary Defense Mechanisms

• Non-immunologic

• Aerodynamic filtration

• Mucociliary transport apparatus

• Clears particulate debris from lungs at 17 mm/min

• Cough reflex

• Immunologic

• Alveolar macrophages – distal airways & alveoli

o Microbial phagocytosis & killing

• Neutrophils – more proximal airways

• Cellular immunity

• Humoral immunity

o IgA - upper airways

o IgG - lower airways & alveoli

Pulmonary Defenses

Pathophysiology

Overwhelmed PDM

• Aspiration of oropharyngeal bacteria

• Pharyngeal / laryngeal dysfunction

• Esophageal dysfunction / choke

• Aspirated foreign bodies

• General anesthesia

• Thromboembolic disease

• Severe bacteremia

Suppression of pulmonary defense mechanisms

• Transportation

• Exercise

• Viral infections

• Stress

• Inhaled toxins (ie. ammonia)

• Poor ventilation / overcrowding

• Immunosuppressive drugs

• Immunologic diseases

• Endotoxemia / systemic diseases

Effects of Transport

Transport is well-accepted as a predisposing factor for respiratory infection

• Increased production of cortisol

• Decreased quantity & bactericidal function of AM

• Decreased mucociliary clearance (dehydration)

• Increased concentration of airborne particulates in airways

• Road & hay dust

• Bacteria & fungi

• Racklyeft, et al, Aust Vet J, 1990

• Restraining the head during transport prevents postural drainage and enhances bacterial colonization of the LRT

• Raidal, et al, Aust Vet J, 1995, 1997

• Confinement with head elevated results in inflammation and increased numbers of bacteria in TBA of horses within 6-12 hours

o Antimicrobial therapy did not alleviate

o Intermittent release of head did not alleviate


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