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Respiratory: neonatal respiratory distress syndrome
Introduction
- Cause: frequently related to prematurity/dysmaturity due to insufficient surfactant in the lungs. Caesarean section and induced parturition can also contribute.
- Prolonged or difficult parturition can cause acidosis in the foal which can also lead to respiratory distress.
- Signs: tachypnea, nostril flaring, increased breathing effort, grunting and pale or cyanotic mucous membranes.
- Diagnosis: history, signs, auscultation, radiography, biochemistry, cytopathology.
- Treatment: intensive supportive therapy is essential for survival.
- Prognosis: guarded.
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Presenting signs
- Tachycardia Heart: ventricular tachycardia.
- Tachypnea.
- Nostril flaring.
- Increased breathing effort.
- Grunting.
- Paradoxic respiration (chest wall collapses during inspiration).
- History of prematurity/dysmaturity Reproduction: prematurity / dysmaturity.
- History of induced labor or caesarean section Uterus: caesarean section.
- History of prolonged or difficult parturition.
- Fractured rib(s) Rib: fracture, eg due to a fall if mare delivered standing, or due to being stood on by the mare.
Acute presentation
- Recumbency.
- Cyanosis.
- Dyspnea.
- Depression.
Age predisposition
- Neonate.
Cost considerations
- Mortalities.
- Intensive 24 hour nursing and supportive therapy.
Special risks
- Anesthesia Anesthesia: general - overview; hypoxia can develop so monitoring of blood gases Blood: gas analysis is essential.
Pathogenesis
Etiology
- Infection EHV1 Equine herpesvirus or EVA Equine viral arteritis virus (less common).
- Prematurity/dysmaturity Reproduction: prematurity / dysmaturity.
- Stress at parturition.
- Rib fracture Rib: fracture during or immediately after delivery.
- Meconium aspiration Respiratory: meconium aspiration.
Predisposing factors
General
- Prematurity/dysmaturity Reproduction: prematurity / dysmaturity.
- Stress at parturition.
- Fractured rib(s) Rib: fracture.
Specific
- Fetal acidosis.
Pathophysiology
Prematurity/dysmaturity
- Insufficient surfactant → incomplete inflation (atelectasis) of the lungs → increased respiratory effort and distress → increased susceptibility to pneumonia.
Fetal acidosis
- Prolonged or difficult parturition → acidosis. The increased carbon dioxide tension of the blood, with the depleted bicarbonate, stimulates the respiratory center → increased rate and depth of respiration.
- If hypovolemic shock is severe, may → depressed respiratory function → further accumulation of hydrogen ions and accentuated acidosis.
Timecourse
- Acute.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Perkins G, Ainsworth D M, Erb H N et al (2000) Clinical, haemotological and biochemical findings in foals with neonatal Equine herpesvirus- 1 infection compared with septic and premature foals. Equine Vet J 31 (5), 422-426 PubMed.
- Stoneham S J (1998) Respiratory distress in the neonatal foal. Equine Vet Educ 10 (5), 242-249 VetMedResource.
- Webb A I et al (1984) Developments in management of the newborn foal distress 2: treatment. Equine Vet J 16 (4), 319-323 PubMed.
- Rossdale P et al (1967) Respiratory distress in a newborn foal with failure to form lung lining film. Nature 215 (5109), 1498-1499 PubMed.