Epidemiological study of canine transmissible venereal tumor (CTVT) in Brazil, 2000–2020

Sex disparity in oronasal presentations of canine transmissible venereal tumour

“…Although the inclusion bias in this database, discussed above, precludes estimation of the true proportion of CTVT cases that manifest oronasally, this finding is consistent with reports that primary oronasal CTVT is an unusual presentation of this disease. 6,21,22,25 The rarity of oronasal CTVT in the population, despite the likelihood that opportunities for licking and sniffing transmission behaviour arise frequently, suggests that transmission of CTVT by sniffing or licking is an unlikely outcome. It is possible that sniffing and licking of CTVT tumours do not usually dislodge cancer cells or that, if dislodged, these cells are unlikely Note: Exact binomial tests were used to compare the observed number of males and females with primary oronasal CTVT to the 1:1 ratio expected under the null hypothesis of no difference between sexes.…”

“…8 However, extragenital body sites, including the skin, eyes, nasal areas, mouth, rectum and internal organs, can also be affected. 6,[9][10][11][12][13][14][15][16][17][18][19][20][21] In these instances, if genital involvement co-occurs, the most likely CTVT seeding routes would appear to be either internal metastatic dissemination or self-transmission. 8,20 The latter could occur, for example, when a dog licks its own genital tumour or makes oronasal contact with its genital tumour while in a curled-up sleeping position.…”

“…9,[11][12][13][14][15][22][23][24] One form of extragenital CTVT that often poses a diagnostic challenge is primary oronasal CTVT. 8,22 Oronasal CTVT is rarely observed, 6,21,22,25 although to our knowledge no studies have systematically addressed its prevalence. Oronasal CTVT tumours present as soft-tissue masses within the nasal or oral cavities, leading to clinical signs such as sneezing, snoring, mucopurulent nasal discharge or bleeding, and facial deformation 23,26,27 (Figure 1).…”

“…Mating is the most common route of CTVT transmission, and CTVT usually manifests clinically as tumours associated with the external genitalia in both male and female dogs 8 . However, extragenital body sites, including the skin, eyes, nasal areas, mouth, rectum and internal organs, can also be affected 6,9–21 . In these instances, if genital involvement co‐occurs, the most likely CTVT seeding routes would appear to be either internal metastatic dissemination or self‐transmission 8,20 .…”

Isolated cutaneous transmissible venereal tumour in dogs

“…In Brazil, most affected dogs are of mixed breed, as these make up the majority of the stray dog population, which was the case of the first animal described in this report 6,7 . There is no sexual predisposition, but some authors report a higher incidence in female 5–7,18 . This may be due to the fact that a single male can copulate with several females and provide a greater dissemination of the neoplasm 3 …”