foal resp diseases Flashcards
Neonatal Respiratory Disease of importance to us
▪ NERDS
▪ Congenital abnormalities
▪ EqALI & EqARDS
▪ Aspiration
▪ Trauma
▪ Bacterial pneumonia
▪ Viral pneumonia
Foal Respiratory Diseases of importance to us
▪ Streptococcus equi subspecies zooepidemicus
▪ Rhodococcus equi
when is a foal considered premature? what can cause this?
- resp dysfunction issues?
▪ Generally <320 days
▪ +/- in utero stress
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Respiratory dysfunction:
▪ Surfactant deficiency > would normally develop in week before birth
▪ Decreased respiratory drive
▪ Weak muscles of respiration
▪ Highly compliant chest wall
▪ Poor lung compliance
Neonatal Equine Respiratory Distress Syndrome
- what is the cause?
- diagnosis?
▪ Non-infectious
▪ Etiology- Surfactant deficiency
- super-premature foals are the major at risk population
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Diagnosis
▪ Hypoxemia- PaO2 <60mm Hg
▪ Progressive hypercapnia
▪ 1 or more risk factors
> <290 days of gestation, or <88% of dam’s previous gestation
> Induction of parturition
> Caesarian section
NERDS DIAGNOSTIC CRITERIA
Abnormal respiration
▪ Persistent tachypnea
▪ Paradoxical respiratory pattern
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Thoracic radiographs
▪ “Ground glass” pattern
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▪ No congenital cardiac disease
▪ Response to O2 > Minimal or absent
NERDS
PATHOPHYSIOLOGY?
progression of disease?
Normal physiology
▪ Surfactant production
> Begins ~ day 290(88%) gestation
> Type II alveolar cells
▪ Roles
> Prevent atelectasis at end of expiration
> Increase pulmonary compliance
▪ Surfactant and lung maturation are not complete at birth
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Abnormal physiology
▪ Surfactant deficiency
> Progressive atelectasis
> Decreased pulmonary compliance
> Ventilation/ perfusion mismatching
> Increased work of breathing
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Progression of disease
▪ Progressive hypoxia and hypercapnia
▪ Respiratory failure
NERDS- TREATMENT
▪ O2 supplementation
▪ Corticosteroids > enhance maturation of lungs
▪ Inhaled bronchodilators
▪ Intravenous fluid therapy
▪ Nutritional support
▪ Systemic antimicrobials
▪ Last line of treatment > Mechanical ventilation
Upper airway congenital abnormalities, and clinical presentation
Examples
▪ Wry nose
▪ Choanal atresia
▪ Cleft palate
▪ Nasopharyngeal cyst
▪ Sub/aryepiglottic cyst
▪ Guttural pouch tympany
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Clinical presentation
▪ Respiratory distress
▪ Dysphagia
common risk factors for acute lung injury in foals <1 week of age
▪ Pneumonia
▪ Sepsis
▪ Meconium or milk aspiration
▪ Thoracic trauma
signs of acute lung injury / acute resp distress syndrome in foal <1 week of age
▪ Acute onset respiratory distress
▪ Presence of known risk factor
▪ Absence of cardiogenic pulmonary edema
▪ Evidence of insufficient gas exchange
▪ Presence of diffuse pulmonary inflammation
acute lung injury vs acute respiratory distress syndrome
- it is a spectrum, depending on PaO2
- acute lung injury is the less severe condition, NARDS is more severe
ACUTE LUNG INJURY & ACUTE RESPIRATORY DISTRESS SYNDROME
- treatment, prognosis
▪ Treat underlying etiology
▪ Oxygen supplementation
> Intranasal
> CPAP
> Mechanical ventilation
▪ Systemic anti-inflammatories
> Corticosteroids early and aggressively
> Taper before discontinuing
▪ Prognosis
> Poor- guarded
neonatal bacterial pneumonia
- pathogenesis
- risk factors
- etiology
Pathogenesis
▪ Hematogenous spread
▪ In utero infection
▪ Meconium or milk aspiration
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Risk factors for sepsis
▪ Prematurity or dysmaturity
▪ Failure of passive transfer
▪ Maternal illness
▪ Poor environmental conditions
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Etiology
▪ Same as septicemia
> E. coli most common
neonatal bacterial pneumonia
- diagnosis and treatment
Diagnosis
▪ Physical examination
▪ Presence of a risk factor
▪ Thoracic ultrasonography
▪ Thoracic radiography
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Treatment
▪ O2 supplementation
▪ Antimicrobials
▪ Supportive care
▪ Treatment of co-morbidities
meconium aspiration syndrome
- risk factors
- pathogenesis
Risk factors
▪ Fetal stress/ hypoxia
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▪ Premature passage of meconium
▪ Pulmonary dysfunction
> Mechanical obstruction
> Surfactant inactivation/ displacement
> Chemical pneumonitis
> Persistent pulmonary hypertension
meconium aspiration syndrome Dx, Tx
Diagnosis
▪ Meconium staining
▪ + Tachypnea & lung consolidation
▪ +/- Respiratory distress
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Treatment
▪ Aspiration of nasal passages/pharynx
▪ O2 supplementation
▪ Anti-inflammatories
▪ Broad-spectrum antimicrobials
milk aspiration in generally secondary to:
▪ Generalized weakness
▪ Poor suckle reflex
▪ Functional abnormality
▪ Congenital abnormality
▪ Botulism
▪ Hyperkalemic periodic paralysis
▪ Bottle feeding
▪ Incorrect nasogastric feeding tube
placement
milk aspiration diagnosis, treatment
Diagnosis
▪ History, physical examination > after suckling, milk comes out nostrils
▪ Upper airway endoscopy
▪ Thoracic radiographs
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Treatment
▪ Correct underlying cause
▪ Nasogastric feeding tube
▪ Broad-spectrum antimicrobials
neonatal viral pneumonia main pathogens
▪ Equine Herpes virus 1
▪ Equine Influenza virus
▪ Equine arteritis virus
neonatal viral pneumonia
▪ Equine Herpes virus 1
> significance? risks?
> clinical signs
> Dx
> Tx
▪ Severe and typically fatal
▪ Farm outbreaks may occur
▪ Premature or sudden parturition
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Clinical signs
▪ Cardiovascular and respiratory distress
▪ Congested and icteric mucous membranes
▪ Severe leukopenia and neutropenia
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Diagnosis
▪ PCR- nasal secretion or whole blood
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Treatment
▪ Acyclovir/ valacyclovir
▪ Supportive care
neonatal viral pneumonia due to equine influenza virus
- how common? who gets it? signs?
▪ Uncommon
▪ Outbreaks > Naïve population
▪ Disease syndrome > Severe bronchointerstitial pneumonia
neonatal viral pneumonia due to equine influenza virus
- signs? disease?
▪ Uniformly fatal
▪ Disease syndrome:
▪ Severe interstitial pneumonia
▪ Edema, weakness, depression
▪ Leukopenia and thrombocytopenia
how common are rib fractures in foals? what types are most common?
complications?
▪ 3-5% of foals
▪ 30% of foals presenting to NICU
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Most common:
▪ Costochondral junction
▪ Multiple fractures
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Complications:
▪ Pulmonary contusions/lacerations
▪ Pneumothorax
▪ Hemothorax
▪ Diaphragmatic hernia
▪ Flail chest
how can we diagnose thoracic trauma in a foal?
▪ Physical examination
> Crepitus or step on palpation
▪ Ultrasonography!
treatment for rib fracutres, based on type
▪ Minimally displaced
> Stall rest
▪ Comminuted, open, complicated
> Surgical repair
▪ Pneumothorax
> Thoracic drain
▪ Hemothorax
> Ligate source, if possible
Most common cause of pneumonia in foals, nature of the infection?
risk factors?
clinical signs?
Streptococcus equi subsp zooepidemicus
▪ Beta-hemolytic gram +, cocci
▪ Commensal organism
▪ Opportunistic infections
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Risk factors
▪ Weaning
▪ Transport
▪ Heat stress
▪ Viral infection
▪ Other bacterial pneumonia
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Clinical signs
▪ Nasal discharge
▪ Cough
▪ Tachypnea
▪ Abnormal respiratory auscultation
▪ Increased respiratory effort
STREP EQUIZOOEPIDEMICUS disease syndromes in foals
Disease syndromes
▪ Pharyngitis/ tracheitis
▪ Guttural pouch empyema
▪ Pulmonary abscesses
▪ Bronchopneumonia
▪ Interstitial pneumonia
STREP EQUIZOOEPIDEMICUS diagnosis and treatment
Diagnosis
▪ Culture
▪ PCR
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Treatment
▪ Supportive care
▪ Anti-inflammatories
▪ Antimicrobials > Sensitivity is important!
RHODOCOCCUS EQUI
- nature of the organism
- epidemiology
▪ Facultative, intracellular gram + coccobacillus
▪ Pathogenic isolates > Plasmid encoding virulence-associated protein (VapA)
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Epidemiology
▪ Isolated from soil
▪ Virulent and avirulent shed in feces
▪ Endemic farms
> Up to 33% of foals clinically affected
> Up to 50% mortality rate
▪ Sporadic disease
RHODOCOCCUS EQUI
▪ Pathogenesis
▪ Median age at diagnosis
> 35-50 days
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Inhaled R. equi
▪ Enter alveolar macrophages
▪ Disrupts endolysosome function (VapA)
▪ Intracellular replication (virR & virS)
▪ Pyogranulomatous inflammation
RHODOCOCCUS EQUI
- clinical syndromes
- clinical signs
Clinical syndromes
▪ Pulmonary disease
> Chronic suppurative bronchopneumonia
> Extensive abscessation
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Clinical signs
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▪ Early disease:
▪ Mild fever
▪ Only when handling/ exercising
> Cough
> Increased respiratory rate
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Moderate disease:
▪ Cough (71%)
▪ Fever (68%)
▪ Lethargy (53%)
▪ Increased respiratory effort (43%)
▪ Decreased appetite
▪ Tachypnea
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Subacute form
▪ Acute death
▪ Acute respiratory distress
> High fever
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Extrapulmonary disease
▪ Gastrointestinal (50%)
> Enterotyphlocolitis
> Abdominal abscess
▪ Polysynovitis (25-33%)
> Multiple synovial structures
> Absence of lameness
▪ Uveitis
▪ Septic arthritis or osteomyelitis
> Moderate-severe lameness
> +/- Effusion
RHODOCOCCUS EQUI
▪ Diagnosis
▪ History & physical examination
▪ CBC
▪ Ultrasonography
> Abscesses
▪ Thoracic radiographs
> Alveolar pattern
> Nodular-cavitary lesions
▪ Tracheal fluid
> Culture
> PCR
rhodococcus equi treatment?
Criteria
▪ Clinical respiratory disease
▪ Extrapulmonary disease
▪ Minimum abscess score
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Antimicrobials (lots of resistance, adverse effects)
▪ Macrolides
> Azithromycin
> Clarithromycin
▪ +/- Rifampin
▪ Duration: Depends on severity
▪ Adverse effects
> Diarrhea, hyperthermia, tachypnea
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▪ Supportive care
▪ Supplemental oxygen
▪ Nebulization
▪ Analgesics
▪ Local therapy for septic arthritis
RHODOCOCCUS EQUI prognosis
▪ Generally <30% mortality rate
▪ Dependent on
> Pneumonia severity
> Presence of extrapulmonary disorders
rhodococcus equi screening
Screening on endemic farms
▪ Thoracic ultrasonography
▪ Rectal temperature
▪ Complete blood count
R. equi Hyperimmune plasma - what does it do and how do we use it?
▪ Decreases risk only
▪ 1 liter within 48 hours of birth
▪ 1 liter between 2-4 weeks of age
