A multi-institutional epidemiologic study evaluating environmental risk factors for feline oral squamous cell carcinoma.

Feline oral squamous cell carcinoma (FOSCC) is an aggressive cancer in domestic cats that has no effective treatment option when advanced. Preventative or early diagnostic measures are thus crucial. FOSCC is also a model for human head and neck SCC (HNSCC); strong risk factors in HNSCC include exposure to alcohol, tobacco, areca nut, and high-risk human papillomavirus. Previous studies have identified flea collar and tobacco smoke exposure, feeding canned tuna, canned cat food and cat foods with chemical additives, living in a rural environment, and having outdoor access as risk factors for FOSCC but there was no overlap in the risk factors between studies. In our study, risks for FOSCC were evaluated in an online epidemiologic survey study in 67 cats with FOSCC and 129 control cats. Clumping clay cat litter and flea collar use were significant risk factors for FOSCC on multiple logistic regression with odds ratios of 1.66 (95% CI 1.20-2.30) and 4.48 (95% CI 1.46-13.75) respectively. Crystalline silica is a carcinogen that may be present in all clay cat litters and tetrachlorvinphos is a carcinogen that is present in the most commonly used flea collars in our study. We recommend further investigation into the association between FOSCC and clay-based litter and/or flea collars containing tetrachlorvinphos.

Unilateral invasive intraocular melanoma with choroidal and optic nerve involvement resulting in bilateral vision loss in a Labrador Retriever.

A 10-year-old male castrated Labrador Retriever cross was referred for evaluation of acute vision loss. Ophthalmic examination revealed mild left sided exophthalmos, bilateral resting mydriasis, an absent direct and reduced consensual PLR in the left eye and reduced direct and absent consensual PLR in the right eye. Examination of the cornea and anterior segment with slit lamp biomicroscopy was unremarkable. Indirect fundoscopy revealed a left optic nerve head obscured by a darkly pigmented lesion. Fundic examination in the right eye was unremarkable. Magnetic resonance imaging revealed a smoothly marginated, lobulated cone to irregularly shaped, strongly T1 hyperintense, T2 and T2 fluid-attenuated inversion recovery hypointense, strongly contrast enhancing mass closely associated with the entire left optic nerve, extending across the optic chiasm and into the right optic nerve ventrally. Full clinical staging revealed no evidence of metastasis. Exenteration of the left eye was performed. Histopathology revealed an unencapsulated, poorly demarcated, multilobulated and infiltrative pigmented mass that was effacing the posterior choroid and optic nerve. The mass was composed of a moderately pleomorphic population of heavily pigmented polygonal cells arranged in sheets and clusters, displaying moderate anisocytosis and anisokaryosis. The population of cells contained moderate amounts of abundant brown-black granular pigment consistent with melanin within the cytoplasm. Mitotic figures averaged approximately three per ten 400× fields (2.37 mm2 ). This is the first report of a melanocytic tumor invading along the optic nerve and tract to result in contralateral vision loss.

Substitution of mitoxantrone for doxorubicin in a multidrug chemotherapeutic protocol for first-line treatment of dogs with multicentric intermediate- to large-cell lymphoma.

OBJECTIVE To evaluate effects of substituting mitoxantrone for doxorubicin in a cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapeutic protocol for first-line treatment of dogs with multicentric intermediate- to large-cell lymphoma. DESIGN Retrospective cohort study. ANIMALS 44 dogs treated with cyclophosphamide, mitoxantrone, vincristine, and prednisone (CMOP) and 51 dogs treated with CHOP at 12 referral institutions. PROCEDURES Medical records were reviewed to determine response to treatment, progression-free survival time, and overall survival time. For dogs treated with CMOP, adverse events were also recorded. RESULTS All 44 (100%) dogs treated with CMOP and 37 of 38 (97.4%) dogs treated with CHOP had a complete or partial response. Median progression-free survival time for dogs treated with CMOP was 165 days (95% confidence interval [CI], 143 to 187 days), and median overall survival time was 234 days (95% CI, 165 to 303 days). For dogs treated with CHOP, median progression-free survival time was 208 days (95% CI, 122 to 294 days), and median overall survival time was 348 days (95% CI, 287 to 409 days). Progression-free and overall survival times were not significantly different between groups. Overall, 9 of the 44 (20%) dogs treated with CMOP had adverse events likely or probably related to mitoxantrone, but all of these adverse events were mild. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that mitoxantrone may be a reasonable substitution in a CHOP protocol for treatment of dogs with multicentric intermediate- to large-cell lymphoma when doxorubicin is contraindicated.