Harderian gland neoplasms in captive, wild-caught Beechey ground squirrels (Spermophilus beecheyi)

Harderian gland neoplasms were identified in 18 aged, adult Beechey ground squirrels (Spermophilus beecheyi) from the records of 167 wild-caught captive animals that were necropsied. All but one animal had tumors that were classified as carcinomas, with infiltrative growth and frequent metastases. This is the first detailed report of Harderian gland neoplasia in wild Sciuridae, although this neoplasm has been described in other rodent species. Clinically, affected ground squirrels typically were inappetent and presented with weight loss and exophthalmos. The biologic behavior of Harderian gland neoplasia is variable among rodent species; in Beechey ground squirrels there was a high incidence of malignant behavior. Eleven of 17 tumor-bearing animals for which the gender was known were male, and 6 were female. Nine of 16 for which data were available were uninfected, and 7 had evidence of current or prior infection with ground squirrel hepatitis virus. Tumor development occurred in older animals; all but 2 were 5.5 years of age or older. The presence of metastasis was not related to gender or chronic ground squirrel hepatitis virus infection.