Lungs Developmental - Pathology

Introduction

• Congenital abnormalities of lungs are very rare, but most common in cattle
• Most congenital abnormalities are incompatible with life

Accessory lungs

• Most common developmental disorder, especially in cattle
• Incompletely differentiated pulmonary tissue present anywhere in the trunk
• Grossly:
  • Lobulated oedematous masses
  • May be connected to uper alimentary tract
• Histologically:
  • Dialated structures resembling bronchioles
  • Alveoli and ducts developed to varying degree
• May cause birthing difficulties

Ciliary dyskinesia

• See Ciliary Dyskinesia

Congenital melanosis

• Affects pigs and ruminants
• Is not clinically significant, often found at slaughter house
• Black spots in various organs, including lungs
• See melanosis in general pathology

Congenital atelectasis

• Incomplete expansion of the lung at birth (congenital) or collapse of previously air-filled lung (acquired)
• Failure of lung tissue to expand at birth
• Ranges from total in stillborn animals to patchy areas in the case of weak neonates, showing more in the dependant lobes in recumbency
• The neonatal respiratory syndrome
  • Best documented in foals but reported in other species
  • Also features extensive atelectasis
  • These animals are called 'barkers' due to the noise made during forced expiration
• Gross pathology:
  • Red fleshy appearance to the affected part, depressed below the surface if there are adjacent normal aerated areas
  • Cut surface oozes blood, perhaps some froth in 'barkers'
  • Affected areas sink or are submerged in fixative
• Micro pathology:
  • Close approximation of capillary walls
  • Little normal alveolar pattern
  • 'Barkers' may have a proteinaceous fluid in alveoli with hyaline membranes in lower airways
• Cause:
  • In weak neonates -inadequate respiratory effort or damage to the respiratory centres in the brain, aspiration of amniotic fluid or meconium
  • In 'barkers'- defective production of surfactant by the Type 2 alveolar epithelium
• Foals that survive may have hypoxic damage to their brain, walk aimlessly and lack normal sense of fear - "wanderers"

Congenital lobar emphysema

• See congenital lobar emphysema

Pulmonary hypoplasia

• Mostly associated with congenital diaphragmatic hernia

Congenital alveolar dysplasia

• Most common in dogs
• Grossly:
  • Lungs retain fetal appearance and are poorly aerated
• Histologically:
  • Uneven size and shape of alveoli, smaller number overall
  • Dilated blood vessels within extensive interstitial tissue
• It is possible that in utero infection may contribute to this

Test yourself with the Lungs Pathology Flashcards

Lungs Pathology Flashcards