Pathology of the oesophagus Flashcards
Oesophagitis
Inflammation of the oesophagus
May be due to frequent regurgitation
Impaction/obstruction of the oesophagus
Commonly in cattle (horses and dogs).
Foreign bodies / solid food - fairly easily to dislodge, more of a problem if feed expands can tear the oesophagus and ingesta can escape into tissues of neck leading to marked inflammation.
Surgery in the oesophagus is very difficult.
Functional bloackage of the oesophagus
Oesophageal motility disorders are termed achalasia, lower sphincter fails to function properly resulting in difficulty in swallowing, regurgitation and weight loss.
E.g. cricopharyngeal achalasia (Cocker spaniels, terriers and miniature poodles).
Megaoesophagus
Or oeosophageal ectasia is diffuse dilation of the organ because of insufficient or uncoordinated peristalsis in the mid and cervical oesophagus.
Occurs in dogs, cats, cows, ferrets, horses, and new world camelids.
Congenital megaoesophagus
Inherited disorder in several breeds – autosomal recessive in Fox Terrier.
Also in Miniature Schnauzer, Great Dane, German Shepherds, and others.
Also in Siamese cats.
Clinical signs of congenital megaoesophagus
See at approx. 6-7 months of age when growing quickly.
Eats food, vomits, eats again and vomits again because oesophagus has no tone to it.
Oesophagus may become extremely dilated producing a megaoesophagus.
Can affect the whole length of oesophagus.
Pathogenesis of congenital megaoesophagus
Appears to be due to delay in maturation of esophageal innervation, either in upper motor neurons of central swallowing centre or in the afferent sensory arm of the reflex involved with peristalsis.
Treatment of congenital megaoesophagus
If dog eats from raised bowel may be satisfactory as food goes down by gravity.
Once in stomach is passed on normally.
Acquired megaoesophagus
Occurs spontaneously in adult in any disorder that disrupts normal reflex involved in swallowing either peripheral or central.
Causes are idiopathic or secondary to oesophagitis, myasthenia gravis (autoantibodies to acetylcholine receptors of the neuromuscular junction), recurrent gastric dilation, hypothyroidism (muscle atrophy and denervation), lead and thallium poisonings (damage on innervation), peripheral neuropathies, tetanus, botulism and myopathies.
Megaoesophagus secondary to vascular rings
Congenital persistence of right fourth aortic arch in dog leads to a vascular ring (aorta, pulmonary artery, and ligamentum arteriosum) around the oesophagus with partial blockage of the lumen of the oesophagus and dilation proximal to the ring. i.e. cranial to the heart.
Which breeds do you see hereditary vascular rings and megaoesphagus
GSDs, Irish setters, grey hounds
Clinical signs of megaoesophagus secondary to vascular rings
Regurgitation of food when puppies weaned onto solid food
Key-Gaskell syndrome
Autonomic polyganglioneuropathy in cats with abnormal function of the sympathetic and parasympathetic system.
Whole autonomic system involved – affected animals usually die.
Similar to grass sickness in horses.
Clinical signs of Kay-Gaskell syndrome
Cats show megaoesophagus, dilated pupils, whole gut is involved (very little peristalsis), constipation.
Generalised autonomic effects: reduced salivation, reduced lachrymation, bradycardia, constipation, and pupillary dilatation.
Pathology of Key-Gaskell syndrome
Histologically there is marked reduction in the number of neurons in all autonomic ganglia in the ventral horn of all levels of spinal cord accompanied by proliferation of non-neuronal cells.
Similar changes in brain stem nuclei of cranial nerves.
