Ophthalmopathologic characterization of multicentric or metastatic neoplasms with an extraocular origin in dogs and cats

Objective To characterize the frequency and distribution of secondary ocular neoplasms in dogs and cats identified during necropsy. Methods A retrospective analysis of necropsy records of dogs and cats was conducted, and cases with metastatic/multicentric neoplasms with an extraocular origin, involving the eyes, were selected. Results From January 2015 to January 2019, we identified a total of 233 dogs and 100 cats with metastatic disease. Of these, 11.6% (27/233) of the dogs and 13% (13/100) of the cats had ocular metastases. Lymphoma was the most common multicentric neoplasm involving the eyes of both species. In dogs, these neoplasms occurred bilaterally, predominantly in the anterior uvea, and were diffuse large B‐cell, T‐lymphoblastic, peripheral T‐cell not otherwise specified, and lymphocytic B‐cell lymphomas. In cats, feline leukemia virus (FeLV)‐associated T‐cell lymphoma was the most common. Mammary carcinoma was the second most common ocular metastatic neoplasm in bitches, with a predominantly unilateral involvement of the uveal tract. In cats, following lymphoma, pulmonary and squamous cell carcinomas were the most common multicentric/metastatic neoplasms of the eyes. Individual cases of cholangiocarcinoma, hemangiosarcoma, and chemodectoma in dogs, as well as mammary gland cribriform carcinoma, salivary gland carcinoma, and histiocytic sarcoma in cats were detected. Conclusions The eyes of dogs were mostly affected by lymphoma or mammary gland carcinoma, while those of cats mostly had lymphoma, pulmonary carcinoma, or squamous cell carcinoma as the main metastatic/multicentric neoplasm. To the best of our knowledge, this is the first study to identify intraocular metastatic cholangiocarcinoma and chemodectoma in dogs, aside from identifying salivary gland carcinoma in cats.