Unraveling the Risk Factors and Etiology of the Canine Oral Mucosal Melanoma: Results of an Epidemiological Questionnaire, Oral Microbiome Analysis and Investigation of Papillomavirus Infection

• Published in: Cancers Vol. 14; no. 14; p. 3397
• Main Authors: de Carvalho, Joyce Pires, Carrilho, Marcella Collaneri, dos Anjos, Denner Santos, Hernandez, Carolina Dagli, Sichero, Laura, Dagli, Maria Lúcia Zaidan
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 13.07.2022; MDPI
• Subjects: Animal sciences; Animals; Deoxyribonucleic acid; DNA; Dogs; Epidemiology; Etiology; Hospitals; Melanoma; Metastasis; Microbiomes; Mucosa; Observational studies; Papillomaviridae; Periodontal diseases; Porphyromonas gingivalis; Questionnaires; Radiation; Risk factors; rRNA 16S; Skin cancer; Statistical analysis; Tannerella forsythia; Toothbrushing; Tumors; Veterinary colleges; Veterinary medicine; Zoology
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers14143397

Oral mucosal melanoma (OMM) is the most common oral cancer in dogs and is very aggressive in this species; its risk factors and etiology are yet to be determined. This study aimed to unravel the risk factors for the development of OMM in dogs and to investigate the possible presence of papillomaviruses as an etiological factor. A case-control study was conducted in 15 dogs with OMM and 15 paired controls whose owners answered an epidemiological questionnaire. Oral swabs from the same dogs were subjected to 16S rRNA sequencing for microbiome analyses. In addition, DNA fragments of OMM had their DNA extracted and amplified by polymerase chain reaction in an attempt to detect canine papillomaviruses. The gingiva was the most frequent anatomical site (47%) of OMM, and most tumors were stage III when diagnosed. Most dogs bearing OMM and the controls had grade 3 periodontal disease, and this factor, along with tartar treatment and tooth brushing, did not differ between cases and controls. Most dogs with OMM and most controls had contact with smokers; there was no statistically significant difference. Canine papillomaviruses were not detected among OMM cases. Tannerella forsythia and Porphyromonas gingivalis were significantly increased in case dogs compared to the controls. As these bacteria are reportedly involved in the pathogenesis of periodontal disease and esophageal cancer in humans, we suggest that they might be risk factors for the development of canine OMM. The limitations of this study include the low number of dogs, and therefore, further studies on canine OMM with larger numbers of animals are encouraged.