esophageal tumors in dogs

Esophageal neoplasia is uncommon in the dog except for osteosarcoma and fibrosarcoma associated with the helminth parasite Spirocerca lupi. Primary esophageal neoplasias are extremely uncommon and include squamous cell carcinoma, scirrhous carci­noma, undifferentiated carcinoma, adenocarcinoma, and leiomyoma, which is the most common.

Clinical signs associated with esophageal neo­plasia include dysphagia, regurgitation, ptyalism, inappetence, progressive weight loss, fetid breath, debilitation, and respiratory signs, which may be secondary to aspiration pneumonia. Clinical inves­tigation includes survey and contrast thoracic radi­ography and esophagoscopy. Definitive diagnosis of esophageal tumors requires a biopsy, either sur­gical or endoscopic, and an official diagnosis by a pathologist. Standard therapy historically has involved medical management for esophageal dys­function and surgical removal when possible. Primary esophageal neoplasia in the canine gener­ally warrants a guarded to poor prognosis. Newer options include laser therapy and photodynamic therapy (PDT). PDT is used relatively routinely in humans, most commonly with localized and min­imally invasive carcinomas. PDT employs a photo­sensitizer and laser light to destroy malignant tissues.

With laser therapy, treatment begins centrally around the residual lumen, proceeding toward but not to the wall. Initial tissue changes are coagula­tive, and then vaporization occurs with ongoing thermal damage. After several days the superficial necrotic tissue is removed, and laser therapy is then performed a few centimeters distal to the site treated several days earlier. Treatment pro­gresses every several days until the lumen is opened through the entire length of neoplastic tissue. Management of S. lupi is discussed in Chapter 4.