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*Congenital abnormalities of lungs are very rare, but most common in cattle
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*Most congenital abnormalities are incompatible with life
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===Accessory lungs===
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*Most common developmental disorder, especially in cattle
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*Incompletely differentiated pulmonary tissue present anywhere in the trunk
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*Grossly:
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**Lobulated oedematous masses
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**May be connected to uper alimentary tract
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*Histologically:
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**Dialated structures resembling bronchioles
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**Alveoli and ducts developed to varying degree
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*May cause birthing difficulties
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===Ciliary dyskinesia===
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*See [[Nasal Cavity Developmental - Pathology#Ciliary dyskinesia|Nasal cavity]]
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===Congenital melanosis===
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*Affects pigs and ruminants
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*Is not clinically significant, often found at slaughter house
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*Black spots in various organs, including lungs
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*See [[General Pathology - Pigmentation and Calcification#Melanin|melanosis in general pathology]]
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===Congenital atelectasis===
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*Incomplete expansion of the lung at birth (congenital) or collapse of previously air-filled lung ([[Lungs Ventilation - Pathology#Atelectasis (Collapse)|acquired]])
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*Failure of lung tissue to expand at birth
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*Ranges from total in stillborn animals to patchy areas in the case of weak neonates, showing more in the dependant lobes in recumbency
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*'''The neonatal respiratory syndrome'''
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**Best documented in foals but reported in other species
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**Also features extensive atelectasis
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**These animals are called 'barkers' due to the noise made during forced expiration
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*Gross pathology:
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**Red fleshy appearance to the affected part, depressed below the surface if there are adjacent normal aerated areas
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**Cut surface oozes blood, perhaps some froth in 'barkers'
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**Affected areas sink or are submerged in fixative
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*Micro pathology:
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**Close approximation of capillary walls
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**Little normal alveolar pattern
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**'Barkers' may have a proteinaceous fluid in alveoli with hyaline membranes in lower airways
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*Cause:
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**In weak neonates -inadequate respiratory effort or damage to the respiratory centres in the brain, aspiration of amniotic fluid or meconium
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**In 'barkers'- defective production of surfactant by the Type 2 alveolar epithelium
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*Foals that survive may have hypoxic damage to their brain, walk aimlessly and lack normal sense of fear - "wanderers"
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===Congenital lobar emphysema===
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*See [[Bronchi and Bronchioles Developmental - Pathology#Congenital lobar emphysema|congenital lobar emphysema]]
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===Pulmonary hypoplasia===
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*Mostly associated with [[Peritoneal cavity - developmental#Pleuroperitoneal diaphragmatic hernia|congenital diaphragmatic hernia]]
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===Congenital alveolar dysplasia===
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*Most common in dogs
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*Grossly:
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**Lungs retain fetal appearance and are poorly aerated
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*Histologically:
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**Uneven size and shape of alveoli, smaller number overall
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**Dilated blood vessels within extensive interstitial tissue
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*It is possible that in utero infection may contribute to this

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