Megaesophagus, Expansion of the Esophagus

Abnormal distention or stretching of the esophagus (also called megaesophagus) can be caused by a congenital defect, or it can occur in an adult dog, either alone or together with other diseases. Congenital megaesophagus usually occurs in Wire-haired Fox Terriers and Miniature schnauzers. In case of congenital disorder which is seen from puppyhood, it is thought to be caused by an abnormality of the nerve that controls contractions of the esophagus.

Causes of Megaesophagus

Megaesophagus can also develop later in life as a side effect of some neurological problem or a problem with a muscle. Some cases of megaesophagus can be caused by myasthenia gravis, systemic lupus erythematosus, polymyositis, hypoadrenocorticism, lead poisoning, dysautonomia, nervous system disorders including cancer, and possibly hypothyroidism. These conditions interfere with the muscle activity in the lower esophagus and at its junction with the stomach.

The condition affects an animal's ability to deliver food to the stomach with resultant pooling of food in the esophagus. If food does not move normally into the stomach, but accumulates in the esophagus, over time the esophagus becomes greatly stretched and dilated and a large amount of food can accumulate there before being regurgitated. Finely ground food must be offered.

Megaesophagus Causes Regurgitation

Megaesophagus is the most common cause of regurgitation in dogs. A dog with megaesophagus requires special care that may include small feeding of high-calorie food of a slurry-like consistency and feeding from an elevated bowl to allow gravity to assist in swallowing. Vigilance by the owner is required because frequent regurgitation can also cause aspiration of the material into the lungs resulting in aspiration pneumonia.

Esophagus Defects in Terrier Dogs

A defect in esophageal muscles responsible for moving food into the stomach without overt megaesophagus occurs in young terrier dogs, and affected animals may not have any clinical signs. Further, an improvement in esophageal motility occurs with time in some dogs, and might represent a syndrome of delayed esophageal maturation.

Congenital Megaesophagus

Congenital megaesophagus is often sufficiently debilitating to a young puppy to result in an owner's request for euthanasia. If medically managed, some puppies may develop a functional esophagus and mature normally; in others, the dilation may persist, but nutritional support may be sufficient to allow skeletal maturation.

References

1. Tom Lonsdale. Work Wonders: Feed Your Dog Raw Meaty Bones
2. Muriel P. Lee. The French Bulldog
3. Esophageal dysmotility in young dogs. Bexfield NH, Watson PJ, Herrtage ME. In: J Vet Intern Med. 2006 Nov-Dec;20(6):1314-8
4. The Merck/Merial Manual for Pet Health. Merck Publishing and Merial (Author), Cynthia M Kahn (Editor), Scott Line (Editor)
5. Watrous BJ, Blumenfeld B. Vet Radiol Ultrasound. 2002 Nov-Dec;43(6):545-9. Congenital megaesophagus with hypertrophic osteopathy in a 6-year-old dog