In the present study, nasal tumours identified were carcinoma (70 per cent; 14/20), transmissible venereal tumour (20 per cent; 4/20) and haemangioma (10 per cent; 2/20).
Ogilvie and LaRue (1992) and
Malinowski (2006) reported that two third of the nasal tumours in dogs was carcinoma.
In the present study, dogs were aged between 1 and 15 years. The mean age of dogs with malignant neoplasia was 8.6 years consistent with the findings of
Ogilive and LaRue (1992). Dogs with nasal TVT in the present study were sexually intact with a mean age of 4 years similar to the findings of
Papazoglou et al., (2001). In the present study, a sex predilection was found for male dogs (male 65 per cent; female 35 per cent) for nasal tumours and was similar to reports of
Malinowski (2006).
Clinical findings of dogs with nasal tumour in the present study are indicated in the in Table 1 and Plate 1. The predominant clinical findings in dogs with neoplasia were mucohaemorrhagic nasal discharge (9/20; 45 per cent), facial deformity (10/20; 50 per cent), stertor (10/20; 50 per cent) and open mouth breathing (3/20; 15 per cent). Haemorrhagic nasal discharge unilateral initially and later progressing into bilateral was mostly consistent with nasal neoplasia
(Plickert et al., 2014). Facial deformity had a strong association with malignant neoplasia. Advanced stage of nasal neoplasia was commonly presented with facial deformity, neurological signs and exophthalmos (
Mortier and Blackwood, 2020). Nasal discharge in dogs with nasal TVT were purely haemorrhagic and was concurrent with sneezing. Similar signs were reported by
Dhillon et al., (2021) in dogs with TVT.
Dogs with intranasal tumours in the present study had a reduced mean red blood cell count, haemoglobin and haematocrit and an increased mean leukocyte count compared to that of the respective mean of the healthy dogs. In contrast, the haematological and serum biochemical values in dogs with neoplasia were unremarkable according to previous studies (Table 2)
(Swinbourne et al., 2014; de
Toledo et al., 2018 and
Hamon et al., 2019). Anaemic changes in dogs with intranasal neoplasia might be due to chronic blood loss in nasal discharge.
The radiographic and tomographic findings in the present study were unilateral or bilateral opacities of the nasal cavity or frontal sinus with or without osteolysis (Plate 2). Radiographic findings in cases of histologically or cytologically confirmed neoplasia were radiopacity, bone lysis and frontal sinus involvement
(Ogilvie et al., 1992; Auler et al., 2015). In skull CT, moderate to severe bone lysis, soft tissue opacity and contrast enhancing mass in the nasal or paranasal sinus was present in all patients diagnosed with nasal tumour (Plate 3).
Saunders et al., (2003) observed soft tissue opacity in skull CT of dogs with neoplasia and opined that cribriform plate compromise, lysis of naso-orbital and periorbital bone strongly suggested malignancy.
The common rhinoscopic changes observed in all dogs with chronic nasal diseases were congestion and excessive fragility concurrent with the findings of
Sapierzynski and Zmudzkaand (2009). Anterior rhinoscopy revealed nasal discharge, nasal mucosal hyperaemia, excessive fragility of nasal mucosa, nasal obstruction by tissue masses and increased space between turbinate due to turbinate destruction (Plate 4). In posterior rhinoscopy, haemorrhage in all the cases and obstruction of choanae with soft tissue mass in some cases were visualized in one case (Plate 4). Endoscopic picture of the nasal cavity made it possible to achieve a preliminary diagnosis of neoplastic disease, which was later confirmed by a histopathological examination of bioptats taken from the lesions. In some cases, biopsying a second sample was hindered by nasal haemorrhage during the same rhinoscopic procedure. Rhinoscopy is inevitable in the diagnosis of nasal disease in dogs despite its inability to fully determine lesion size and extension. Although malignant and non-malignant lesions are histologically differentiated based on rhinoscopy guided biopsies, secondary changes like the presence of fibrin deposits, necrosis and inflammation affects the quality of biopsy samples which interrupts the actual histologic interpretation and diagnosis
(Auler et al., 2015).
Cytological analysis revealed carcinoma and transmissible venereal tumour cells in nasal swab cytology (Plate 5). The typical cytological characteristics of nasal cytology in dogs with nasal TVT were numerous discrete, round, individual cells with a moderate to high nuclear: cytoplasmic (N:C) ratio, moderate amounts of pale, basophilic cytoplasm and small, round, clear, punctate vacuoles in cytoplasm similar to the findings of
Parker et al., (2021). The cytological features of carcinoma were cohesive sheets of cells with anisocytosis, anisokaryosis and marked nuclear to cytoplasmic ratio. Histopathological changes in the present study in dogs with adenocarcinoma were numerous glandular structures lined by proliferating epithelial cells with prominent nucleus and nucleoli whereas in haemangioma numerous dilated, hyperplastic and pleomorphic submucosal glands were evident. Variably sized squamous epithelial cells surrounded by inflammatory cells were the histologic features in dogs with nasal squamous cell carcinoma (Plate 6). Similar cytological and histopathological features were described by
Bancroft and Gamble (2008) and
Burton (2018) in dogs with nasal neoplasia.
