Carcinoids are a heterologous group of neuroendocrine tumors that occur in various regions of the GI tract, liver, lung, and occasionally heart. In dogs and cats, carcinoids have been reported to occur in the stomach.
Etiology and Pathogenesis of Carcinoids in Animals
Carcinoid tumors arise from neuroectodermal cells.
In humans (but not yet documented in companion animals), carcinoid tumors serve as a source of serotonin or histamine. Excessive release of these transmitters can cause a syndrome of flushing, hypotension, wheezing, and diarrhea in humans.
In dogs and cats, carcinoid tumors may cause obstruction in the GI tract or metastasize to lymph nodes and other tissues.
Epidemiology of Carcinoids in Animals
Carcinoid tumors are rare in dogs and cats.
Clinical Features of Carcinoids in Animals
Clinical signs of carcinoid tumors vary with the location of the tumor. The most common clinical signs include chronic vomiting, anorexia, diarrhea, and weight loss.
Diagnosis of Carcinoids in Animals
Carcinoids can be presumptively diagnosed based on signalment, history, clinical signs, physical examination findings, and results of diagnostic imaging. Definitive diagnosis of carcinoid tumors is determined histologically after biopsy or resection.
Treatment and Prognosis of Carcinoids in Animals
Surgical removal is the treatment of choice for carcinoid tumors.
In general, prognosis for carcinoid tumors is guarded. Metastasis is common at the time of diagnosis.
Key Points
Carcinoids occur in various regions of the GI tract, liver, lung, and occasionally heart.
Surgical removal is the treatment of choice.
