We read with interest the article by Ewens et al. entitled, “Fluorouracil Plus Leucovorin Induces Submandibular Salivary Gland Enlargement in Rats,” which appeared in Toxicologic Pathology
33, 507–515. However, we question whether the lesions were a direct effect of chemical administration, since chemically mediated immunosuppression followed by an exacerbation of sialodacryoadenitis virus (SDAV) infection could result in similar lesions. SDAV infection, which is a common infectious disease of laboratory rats, commonly results in inflammation of the submandibular salivary gland with relative or complete sparing of the sublingual gland. Infection of the Harderian glands, which is very common with SDAV infection, could explain the facial swelling that was described in the article. The methods section does not indicate whether the Harderian gland was examined histologically, nor does it indicate whether SDAV infection in the colony was investigated by serologic testing. The possible involvement of SDAV infection should be ruled out when this spectrum of lesions is encountered in laboratory rats.
