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- 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
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
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