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

Abstract

Background: Canine transmissible venereal tumour (CTVT) is a widely spread, contagious neoplasm commonly found in dogs. Mostly affects the external genitalia, however, it may also exhibit unusual clinical presentations. Aim: To describe the epidemiology, clinical appearance, cytologic and histopathologic features of dogs with TVT in Morocco. Methods: Within the realm of a nation-wide study on canine and feline tumours in Morocco between September 2020 and March 2023, dogs with histologically diagnosed TVT were identified and data on epidemiologic, clinical as well as cytologic and histologic features compiled and analyzed. Results: A total of 64 cases of canine TVT were diagnosed. 52 dogs were cross-breed (81.2%) while 4 Siberian Huskies (6.2%) and 3 German shepherds (4.7%) were the most affected pure-breed dogs. Median age of dogs at diagnosis was 3 years (range, 1-10years) and male gender was more common (male:female ratio; 1.3:1). Tumour was located exclusively in the genital area in 58 cases (90.6%), whereas 6 dogs (9.4%) had an atypical occurrence of TVT with locations including skin and nasal cavity. Cytology allowed for an early diagnosis in 2 cases. Histology revealed no differences between the genital and extragenital forms. Immunohistochemistry was necessary in 4 cases and revealed positive staining for vimentin and Alpha-1-antitrypsin, negative marking for CD3, CD20 and AE1/AE3, and low cytoplasmic labeling for lysozyme. Conclusion: CTVT is a widely distributed neoplasm in Morocco, mostly showing presence in young, cross-breed, and oftentimes stray dogs. Adequate understanding of this tumour's epidemiological features is necessary for its management and eradication.