Lomustine for treatment of canine transmissible venereal tumor

Abstract

Canine transmissible venereal tumor (TVTC) is a highly casuistic transmissible neoplasm in Brazil. Chemotherapy with vincristine sulfate is considered the treatment of choice, but the need for weekly applications and hematological monitoring, in addition to costs, are obstacles to owners’ adhesion to the treatment. Lomustine is an alkylating class antineoplastic agent, and because it is administered orally, it is a more practical and less costly treatment option for the owners of animals with neoplasms sensitive to the drug. This study evaluated the therapeutic efficacy of lomustine in dogs affected by TVTC. Twelve dogs with cytopathological diagnosis of natural genital TVTC were selected. The dogs were submitted to the experimental protocol with lomustine administration at doses of 70 to 85 mg/m2 orally every 21 days, totaling a maximum of two administration cycles. The animals were reevaluated every 7 days until a maximum of +49 days after the first dose of lomustine, to monitor the regression of neoplastic lesions through measurements. Among the 12 dogs submitted to the lomustine protocol, 8/12 achieved complete remission of the neoplasm and were considered cured (66.6%), 1/12 had partial response to treatment (8.33%) and 3/12 had stable disease (25%). Important adverse effects such as severe neutrophilic leukopenia were detected in 3/12 dogs (25%). The clinical study indicated that lomustine may be a treatment option for TVTC.

Canine transmissible venereal tumour in Morocco: Clinical and pathological findings in 64 dogs – Insights from a descriptive epidemiological study (2020-2023)

“…A higher prevalence of TVT was found in dogs classified in the age range of 2 to 5 years old (81.3%). This was in accordance with the findings of similar studies and is thought to be due to greater sexual activity in these age groups ( Chikweto et al, 2013 ; Costa et al, 2023 ). In any case, this is in contrast to most other neoplastic entities that represent more geriatric diseases, and in this may aid in diagnosis, especially of atypical tumors.…”

“…Affected dogs were mostly cross-breed, which is mainly due to the large population of stray dogs associated with a higher risk of transmission. This correlates with findings from several other studies ( Araujo et al, 2016 ; Schectman et al, 2022 ; Costa et al, 2023 ). Additionally, pure-breed dogs were also reported in our study.…”

“…Data concerning the sexual predisposition of CTVT are still conflicting and vary considerably. Some studies showed no significant differences regarding the sex of affected animals ( Chikweto et al, 2013 ; Schectman et al, 2022 ; Costa et al, 2023 ), meanwhile, other reports revealed higher prevalence in female dogs ( Araujo et al, 2016 ). However, in our study, CTVT was more prevalent in males, similar to what has been reported by Arcila-Villa et al (2018) .…”

“…The external genitalia of both sexes is the most frequently affected site ( Araujo et al, 2016 ; Abedin, 2020 ). Less commonly, atypical cases of CTVT are present, including cases with extragenital lesions reported at various sites such as the skin, eyes, oral, and nasal cavity ( Komnenou et al, 2015 ; Thatcher et al, 2020 ; Costa et al, 2023 ), and metastasis involving, regional lymph nodes, brain, muscles, skin, liver, spleen, and kidney ( Park et al, 2006 ; Pinczowski et al, 2015 ; Alkan et al, 2017 ).…”

“…These are usually localized, hemorrhagic, possess a cauliflower-like growth pattern, and a friable texture. Tumors may be single or multiple, ranging from a small nodule to a large mass ( Muste et al, 2012 ; Abedin, 2020 ; Murchison, 2021 ; Costa et al, 2023 ). Genital lesions are mostly associated with preputial and vaginal hemorrhagic discharge, as well as increased licking of the affected region.…”