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Authors: McNeil EA, Tumolo GL, Powers BE, Reif JS, Nash DJ, LaRue SM
Publications: 2001;:
Species: Dogs
Diseases: Gastric Cancer
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Gastric cancer is an infrequent diagnosis in dogs, comprising less than 1% of canine malignancies according to the literature. Seventy to 80% of gastric cancers in dogs are carcinomas, with males more commonly affected than females. A breed predisposition in Belgian shepherds has previously been hypothesized, but has not been investigated epidemiologically. In recent years, we have noticed an apparent over-representation of Chow Chows with a diagnosis of gastric adenocarcinoma. To determine the relative frequency of gastric adenocarcinoma in Chows compared to dogs of other breeds and to describe the clinical and histologic features of gastric cancer in Chows, we conducted searches of the databases of the Colorado State University Veterinary Teaching Hospital (CSU-VTH) and the Veterinary Medicine Database at Purdue University (VMDB). The VMDB is a national database that contains abstracted information on animals presenting to veterinary hospitals at 26 universities in North America. From each source, we determined the proportion of dogs, in general, and Chows, specifically, diagnosed with gastric carcinoma. From medical records, we have abstracted some clinical data. Histopathology specimens are currently being reviewed by a single pathologist (BEP). At the CSU-VTH between 1/1/99 through 12/31/00, 54,639 dogs were evaluated. Only 602 (1.1%) of these dogs were classified as Chows. Sixty-six dogs (0.12%), including eight Chows, were diagnosed with carcinoma of the stomach during this same time period. Therefore, 12% of gastric carcinomas were diagnosed in Chows. The diagnosis of gastric carcinoma was made in 1.3% of Chows presenting to the CSU-VTH, 10 times the frequency determined for the entire canine population. For the period between 1/1/99 and12/31/00, the VMDB has records on 440,517 individual dogs of which 4,058 (0.9%) are Chows. Only 205 dogs (0.04 % of the VMDB population) had a diagnosis of gastric carcinoma. Approximately sixteen percent (32 cases) of the gastric carcinomas occurred in Chows. The prevalence odds ratio for gastric carcinoma in chows in this population was 20.2 (95% confidence interval = 13.6 - 30). In both the general dog population and in Chows, gastric tumors were evenly distributed between male and female dogs. The age at diagnosis for affected chows ranged from 5 to 12 years with a median of 9 years for the CSU-VTH and from 4 to 15 years with a median in the 7 - 10 year range for the VMDB. This is comparable to age at diagnosis for dogs of other breeds. These results strongly suggest a breed predisposition to gastric cancer. The etiology of gastric cancer in dogs is not yet understood. In humans, both environmental (consumption of nitrates and salted meat, deficiency of micronutrients and antioxidants, helicobacter pylori infection) and genetic (racial and ethnic differences, familial occurrences) factors are thought to contribute to gastric carcinogenesis. Our results suggest that genetic influences may also dictate gastric cancer susceptibility in dogs. Currently, we are 1) conducting a case-control study to evaluate for environmental influences in the development of gastric cancer in Chows, and 2) collecting pedigrees from affected and unaffected Chows to evaluate mode of inheritance.
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