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Lungs Developmental - Pathology (view source)
Revision as of 12:30, 20 August 2008
, 12:30, 20 August 2008no edit summary
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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===
*See [[Nasal Cavity Developmental - Pathology#Ciliary dyskinesia|Nasal cavity]]
===Congenital melanosis===
*Affects pigs and ruminants
*Is not clinically significant, often found at slaughter house
*Black spots in various organs, including lungs
*See [[General Pathology - Pigmentation and Calcification#Melanin|melanosis in general pathology]]
===Congenital atelectasis===
*Incomplete expansion of the lung at birth (congenital) or collapse of previously air-filled lung ([[Lungs Ventilation - Pathology#Atelectasis (Collapse)|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 [[Bronchi and Bronchioles Developmental - Pathology#Congenital lobar emphysema|congenital lobar emphysema]]
===Pulmonary hypoplasia===
*Mostly associated with [[Peritoneal cavity - developmental#Pleuroperitoneal diaphragmatic hernia|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