Molecular and immunohistochemical studies do not support a role for papillomaviruses in canine oral squamous cell carcinoma development.

Oral squamous cell carcinomas (OSCCs) are common neoplasms of dogs and are of unknown cause. Whereas papillomaviruses (PVs) are an established cause of human OSCCs, few studies have investigated canine OSCCs for a PV aetiology. In humans, a PV aetiology can be determined by detecting PV DNA and PV-induced increased p16(CDKN2A) protein (p16) within the OSCC. In this study, PCR, using four different primer sets and p16 immunohistochemistry, was used to evaluate 28 canine OSCCs for a possible PV aetiology. None of the primers amplified PV DNA from any of the OSCCs although four neoplasms contained intense p16 immunostaining. Intense p16 immunostaining would indicate a PV aetiology in a human OSCC but the absence of PV DNA suggests that the increase in p16 was not due to PV infection. Overall the results indicated that PVs are not a significant cause of canine OSCCs.

Multiple oral carcinomas associated with a novel papillomavirus in a dog.

Papillomaviruses (PVs) are well recognized to cause human oral squamous cell carcinomas (SCCs). However, there is currently little evidence that PVs similarly cause oral cancer in dogs. In the present case, a dog developed an invasive SCC and multiple in situ carcinomas within the mouth. Cell changes consistent with PV infection were prominent within the neoplasms and the surrounding gingiva. Immunohistochemical staining revealed PV antigens and intense p16(CDKN2A) protein (p16) immunostaining within the invasive SCC. Papillomaviral DNA sequences were amplified from the invasive and in situ carcinomas. Sequencing revealed that the DNA was from a novel PV that appears most closely related to canine PV-2 and -7. To the authors' knowledge, multiple carcinomas have not been previously reported in the mouth of a dog. Additionally, the current study describes PV cytopathology in a canine oral SCC. Whether the PV infection influenced neoplasm development cannot be definitively determined in this case. However, the presence of p16 immunostaining and the development of multiple oral carcinomas support a role of the PV in tumorigenesis in this dog.

Cardiogenic arterial thromboembolism causing non-ambulatory tetraparesis in a cat.

A 1-year-old oriental cat was presented with a peracute onset of tetraparesis and vocalisation. Clinical findings were suggestive of multi-site thromboembolic disease, and this was confirmed on post-mortem examination. An echocardiogram showed severe restrictive cardiomyopathy and spontaneous echogenic contrast. To the author's knowledge, this is the first reported case of tetraparesis secondary to cardiogenic arterial thromboembolic disease. Thromboembolic disease should be included as a differential diagnosis for any cat presented with a peracute onset of paresis or paralysis, even if there is no history of cardiac disease.