Signalment:
Canine, Labrador Retriever/Collie cross, 7 years old, male neutered, 57 lbs.
Clinical history:
The dog presents with poor appetite and moderate lethargy for two months and weight loss. The results of the Ehrlichia canis
and Lyme disease tests are negative and the Rocky Mountain spotted fever test is positive at 1:128. Therapy has included tetracycline.
Physical examination:
The findings include rectal temperature 102.6° F, heart rate 120/min, slightly pale mucous membranes, and normal capillary
refill time. Normal heart and lung sounds are heard. Abdominal distension, thinness, and generalized muscle wasting are noted.
Laboratory results:
A complete blood count, serum chemistry profile and urinalysis are outlined in Table 1.
Ultrasound examination:
Thorough abdominal ultrasonography was performed.
Table 1: Results of laboratory tests
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My comments:
There is a moderate amount of free fluid accumulated within the abdominal cavity. The liver shows a uniform echogenicity in
its parenchyma. No masses noted within the liver parenchyma. The gall bladder is mildly distended, and its walls are not thickened
or hyperechoic. The spleen shows a uniform echogenicity in its parenchyma - no masses noted. The left and right kidneys are
similar in size, shape and echotexture. No masses or calculi were noted in either kidney. The urinary bladder is distended
with urine and contains some urine sediment material - no masses or calculi noted. The left and right adrenal glands are similar
in size and shape. The stomach wall is irregularly thickened and echobright. The small intestinal wall is normal. The pancreas
is enlarged.
Cytologic examination:
About 1,300 milliliters of ascitic fluid was removed prior to further ultrasonographic evaluation. Fine needle aspirations
of the stomach wall and sample of ascitic fluid for cytologic examination were collected and submitted for laboratory evaluation.
The cytologic results indicate gastric wall adenocarcinoma and neoplastic effusion secondary to disseminated carcinoma (carcinomatosis).
Case management:
In this case, gastric wall adenocarcinoma with metastatic spread is the clinical diagnosis. Clinically, there is not much
one can do for this case with this histopathologic diagnosis. Chemotherapy may be attempted but carries a grave prognosis.
Image 1.
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Review of gastric neoplasia
Gastric neoplasia accounts for less than 1 percent of all canine malignancies. Adenocarcinoma is the most common type, affecting
older (average age between 7.5 to 10 years) male dogs.
Other malignant tumors include leiomyosarcoma and lymphoma. Benign tumors (adenomas and leiomyomas) are uncommon and affect
older dogs (average age being 16 years).
Image 2.
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Lymphosarcoma is the most common gastric neoplasm in cats. Gastric adenocarcinomas are most common on the lesser curvature
and pylorus and often involve most of the gastric body. Metastases are common, especially in the gastric lymph nodes, but
also in the spleen, liver, omentum, peritoneum and lungs. Gastric lymphosarcoma may appear as a single mass or multiple, often
ulcerated nodules, or as a diffuse infiltrative lesion. Regional lymph nodes are often involved. Adenomas present as polypoid
masses, which may occlude the pylorus. Leiomyomas present as single or multiple sessile, firm polyps, covered by a normal
mucosa. They are localized in the gastric body or near the cardia.
Diagnostic considerations
Dogs with gastric adenocarcinoma usually present with vomiting, anorexia and weight loss. The duration of clinical signs is
from weeks to months. Definitive diagnosis of neoplasia requires full-thickness biopsy of the stomach. However, a tentative
diagnosis may be made based on supportive signalment and history. Clinical pathology findings are inconsistent. Pre-renal
azotemia, hypokalemia, hypochloremia, metabolic alkalosis, anemia and hypoalbuminemia can occur because of chronic vomiting.
Image 3.
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Metabolic abnormalities are uncommon as most animals suffer low-grade, chronic vomiting. However, severe and protracted vomiting
may be associated with metabolic alkalosis and paradoxical aciduria.
Survey and contrast radiography, endoscopy and ultrasonography may be used in the diagnosis of gastric adenocarcinoma in dogs.
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