Bacterial pneumonia in horses Flashcards
3 most common gram pos. bacteria to cause pneumonia in horses
G+ Streptococcus equi subsp. zooepidemicus, Staphylococcus aureus,
Strep. pneumoniae
5 most common gram neg. bacteria to cause pneumonia in horses
G -
Pasteurella spp.,
Actinobacillus spp.,
E. coli,
Klebsiella pneumoniae,
Bordetella bronchiseptica
3 most common anaerobe bacteria to cause pneumonia in horses
Anaerobic:
Bacteroides fragilis,
Peptostreptococcus anaerobius,
Fusobacterium spp.
One of the most common causes of pneumonia in horses is
transportation.
Also May develop after
* Viral infections
* Athletic events (races) with High-intensity exercise – may aspirate track debris and oropharyngeal secretions.
* General anesthesia
* Overcrowded, poor nutrition, exposion to cold and wet weathe.
* Laryngeal and pharyngeal dysfunction
* Aspiration of oropharyngeal bacteria
* Oesophageal obstruction→ aspiration pneumonia!
Clinical signs of pneumonia in horses.
Early stages
* Gurgling sound of exudates in the trachea
* Fever
* Depression
As pneumonia progresses
* Intermittent fever
* Tachypnea or respiratory distress
* Nasal discharge
* Mucopurulent
* Coughing
* Inappetence
* Exercise intolerance
* Weight loss
Clinical findings of pneumonia in horses.
On Auscultation of the thorax:
* Harsh breath sounds dorsally
* Crackles, wheezes, dullness of respiratory sounds ventrally
- Manipulation of the trachea or larynx may induce cough
- Halitosis indicates an anaerobic infection!
- Mandibular lymphadenopathy, but also rule out Strangles, viral infections.
How do you collect your culture in equine pneumonia?
Culture: Transtracheal aspiration
* Aerobic and anaerobic cultures
Treatment of equine pneumonia.
Based on Culture and sensitivity results, but If absent→ broad spectrum AB.
* IV penicillin + aminoglycoside or third-generation cephalosporine (+ metronidazole)
* AB therapy may also be administered by nebulization e.g. Gentamicin, ceftiofur, marbofloxacin
* In general, 1/3 of the systemic dose.
With Gram neg. infections and endotoxemia
* Flunixin meglumine 0,5-1,1 mg/kg IV q12h
* Prophylactic measures against laminitis!
Supportive care
* ↓stress, adequate ventilation and hydration, high quality forages
Correct the primary cause of the pneumonia!
* Depending on the chronicity – clinical improvement in should be seen in 48-72 h.
Prognosis and prevention of equine asthma.
Prognosis Can be excellent if treated aggressively.
* recovery in 2-6 weeks
Prevention
* Adequate immunization protocols. Vaccinate against influenza, EHV-1 and EHV-4.
* Decrease stressors like Long transportation
* Good management: decrease dust and noxious gases.
* Prevent exposure to inclement weather
* Provide adequate nutrition
Causes of pleuropneumonia/septic pleuritis.
- Pneumonia or pulmonary abscessation
- Thoracic trauma, esophageal rupture, penetration of the esophagus/stomach by
a foreign body.
Most often isolated
* Aerobes: Streptococcus spp., Pasteurella and Actinobacillus spp., E. coli, Enterobacter spp.
- Anaerobes: Bacteroides spp., Peptostreptococcus spp., Fusobacterium spp., Clostridium spp.
Epidemiology & pathophysiology for pleuropneumonia/septic pleuritis.
Risk factors are the same as for pneumonia.
* Long-distance transportation, strenuous exercise, viral respiratory tract disease, surgery, dysphagia, general anesthesia, systemic illness (enteritis).
Cumulative causative factors:
Pulmonary defence mechanisms decrease leading to:
* Bacterial contamination of the lower respiratory tract.
* Extension of the infectious process into the pleural space causes pleuritis.
* Parenchymal inflammation increases permeability of the capillaries in the visceral pleura → fluid
accumulation. In the fluid: protein, cells, bacteria.
Transportation pleuropneumonia aka …?
„shipping fever“
Transportation stress causes a decrease in neutrophilic phagocytosis.
Head in elevated position causes Decreased mucociliary clearance when 6-12 h continuous transport.
Prevention by
* Travel head free
* Stop every 6 hours, preferably take the horse out of the trailer.
* Good ventilation
Clinical signs of pleuropneumonia/septic pleuritis.
May be confused with colic and rhabdomyolysis.
ACUTE STAGE:
* Febrile, lethargic, slight nasal discharge, cough,
shallow breathing pattern
* Painful, stilted gait
* Thoracic auscultation may be abnormal
* Pleural friction rubs, ventral dullness
SEVERE ACUTE CASE:
* Nostril flaring
* Tachycardia
* Jugular pulsations
* Toxic mucous membranes
* Guarded, soft cough
* Serosanguineous fetid nasal discharge
Chronic cases:
* More than 2 weeks
* Intermittent fever
* Weight loss
* Substernal and limb edema
Diagnosis of pleuropneumonia/septic pleuritis.
- History + clinical examination
Thoracic auscultation - Dorsally – vesicular sounds; ventrally – no lung sounds
- Cardiac sounds radiateover a wider area than normally
Thoracic percussion - May elicit a painful response (pleurodynia)
Blood analysis
* Acute cases: normal or toxemic leukogram and chemistry findings
* Chronic: anemia, neutrophilia, hyperfibrinogenemia, hyperproteinemia
U/S for Diagnosis of pleuropneumonia/septic pleuritis.
Ultrasound can detect free or loculated fluid, pleural thickening, pulmonary and mediastinal abcesses, pulmonary consolidation, inundation of airways with fluid, fibrinous adhesions, concurrent pericarditis.
* Enables accurate placement of the catheter during thoracocentesis
* Fluid may appear anechoic or hypoechoic depending on the relative cellularity
* Free gas echoes within the pleural fluid
* Anaerobic organisms
* Presence of air introduced during a thoracocentesis or by a bronchopleural fistula
In addition to Transtracheal aspiration, what other sample should be taken in cases of pleuropneumoniae?
Pleural fluid aspirates
* Thoracocentesis – diagnostic, prognostic and may be life-saving (severe respiratory distress!)
* Culture, cytology
How long should AB therapy for pleuropneumoniae last?
Therapy should continue for 2-4 months until the horse is gaining weight, hematologic and serum chemistry values have normalized, and no evidence of respiratory tract disease exists.
- Limited excercise (hand walking)
- Avoid stress
Prognosis in equine pleuropneumoniae?
Early identification and agressive treatment gets the most favorable response.
- Survival rates for acute pleuropneumonia range between 49-98%.
- Prognosis deteriorates with the increased duration of illness.
- Involvment of anaerobic bacteria and development of complicating factors like pleural adhesions etc. worsen prognosis.
