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→Congenital Achalasia
====Congenital Achalasia====
====Congenital Achalasia====
[[Image:Megaoes.gif|left|thumb|125px|<small><center>Megaoesophagus (Copyright Alun Williams 2009 (RVC))</center></small>]]
[[Image:Megaoes.gif|left|thumb|125px|<small><center>Megaoesophagus (Copyright Alun Williams 2009 (RVC))</center></small>]]
Congenital megaoesophagus is sometimes called 'congenital achalasia' but this implies a defect of the cardiac sphincter of the stomach (as in man) whereas the canine condition affects the whole oesophagus. This disease is inherited in a number of breeds of dog, including the fox terrier (in an autosomal recessive manner), miniature Schnauzer (dominantly with 60% penetrance), great Dane, Irish setter, Chinese Shar-pei, Newfoundland and German shepherd. It is also an inherited disorder of the Siamese cat where it may occur with concurrent pyloric stenosis.
The disease is thought to result from a delay in the maturation of either upper motor neurones in the central swallowing centre in the brainstem or of the afferent sensory arm of the peristaltic reflex. The resultant hypomotility of the oesophagus leads to a functional obstruction and boluses of food do not reach the stomach and are eventually regurgitated. The condition is seen most commonly at 6-7 months during a period of rapid growth. Affected animals eat, regurgitate shortly afterwards and may then attempt to eat again. As with any disease that results in chronic regurgitation, affected animals lose weight due to malnutrition and may also develop aspiration pneumonia.
The disease is thought to result from a delay in the maturation of either upper motor neurones in the central swallowing centre in the brainstem or of the afferent sensory arm of the peristaltic reflex. The resultant hypomotility of the oesophagus leads to a functional obstruction and boluses of food do not reach the stomach and are eventually regurgitated. The condition is seen most commonly at 6-7 months during a period of rapid growth. Affected animals eat, regurgitate shortly afterwards and may then attempt to eat again. As with any disease that results in chronic regurgitation, affected animals lose weight due to malnutrition and may also develop aspiration pneumonia.
Diagnosis, treatment, prognosis.
Diagnosis, treatment, prognosis.
====[[Vascular Ring Anomalies|Vascular Ring Anomalies]]====
====[[Vascular Ring Anomalies|Vascular Ring Anomalies]]====