Megaesophagus in Dogs
Megaesophagus is a generalized enlargement of the esophagus -- a muscular tube connecting the throat to the stomach -- with a decreased to absent motility. Esophageal motility is required for moving food and liquid down to the stomach.
Megaesophagus is seen more often in dogs as compared to cats. Some breeds are born (congenital) with this problem; for example, wire haired fox terriers and miniature schnauzers. Other breeds reported to be predisposed to this condition include: German shepherds, dachshunds, great Danes, Irish setter, Labrador retriever, pug, and Chinese shar-pei.
Symptoms and Types
Regurgitation is considered the hallmark sign of megaesophagus. Also, aspiration pneumonia may develop due to the entrance of food or liquid into the lungs. Other common symptoms include:
- Nasal discharge
- Increased respiratory noises
- Weight loss (cachexia)
- Extreme hunger or lack of appetite (anorexia)
- Excessive drooling (ptyalism)
- Bad breath (halitosis)
- Poor growth
Megaesophagus can either be congenital in nature (born with) or acquired later in life. The congenital form is typically idiopathic or due an unknown cause; although it is rarely due to myasthenia gravis. The acquired form is also commonly idiopathic, but may also be due to:
- Neuromuscular disease (e.g., myasthenia gravis, distemper, myositis)
- Esophageal tumor
- Foreign body in esophagus
- Inflammation of esophagus
- Toxicity (e.g., lead, thallium)
- Parasitic infections
Your veterinarian will first ask you for a thorough history of your dog’s health. He or she will then perform a complete physical examination on your dog and attempt to differentiate, with your description, whether it is regurgitating or vomiting, which is important in ruling out underlying diseases that cause vomiting. The shape of expelled material, presence of undigested food, and length of time from ingestion to vomiting (or regurgitation) will also help differentiate between these two issues.
Routine laboratory tests, including complete blood count (CBC), biochemistry profile, and urinalysis results, are usually normal in dogs with megaesophagus. However, abnormalities related to underlying diseases or complications, like aspiration pneumonia, may be seen. Radiographic studies will show the enlarged esophagus filled with fluid, air, or food, and will help identify abnormalities related to aspiration pneumonia.
More advanced techniques, like esophagoscopy, will be sometimes be employed, too. Esophagoscopy allows for the examination of the interior of the esophagus using an esophagoscope, a thin, tube-like instrument with and light and lens for viewing the inner areas of esophagus. It also allows for the removal of foreign bodies, evaluation of obstruction, and neoplasia.