A total of 1,768 cases of neoplasia in dogs were entered into the DVCR during the study period. 765 of these (43%, confidence interval (CI): 41.0-45.6) were located in the skin, subcutis or adnexa and had a diagnosis established by cytology or histopathology. Another 21 cases without a cytologically or histopathologically confirmed diagnosis were reported to the DVCRbut were omitted from the study.
Of the 765 cases, 400 cases (52%, CI: 48.8-55.8) were males, including 91 neutered), and 363 reports (48%, CI: 43.9-51.0) were on females, including 103 neutered. In 2 cases, information on gender was provided.
The majority of reports concerned benign tumours (66%, CI: 62.8-69.5, 506), while 21% (n = 160, CI: 18.0-23.8) were reports on malignant neoplasms. In 99 cases (13%, CI: 10.6-15.3) biological behaviour was not provided. The location of the neoplasms were primarily in the cutis, subcutis or in the perianal region (Table ).
Location and behaviour of neoplasms. Data from the Danish Veterinary Cancer Registry.
The most commonly encountered malignant neoplasms were MCT and soft tissue sarcomas (STS) and for benign neoplasms lipomas and histiocytomas (Table ).
Most commonly encountered neoplasms including the diagnostic method utilised and percentages of cases operated
The majority of cases (62%, CI: 58.4-65.3) were treated surgically (Table ). Surgery was performed in 61% (CI: 56.2-64.7) of the benign cases and in 70% (CI, 62.9-77.1) of the malignant cases. The diagnostic method used to verify the diagnosis as well as the proportion of cases where surgery was performed is shown in Table . Microscopic evaluation by cytology or histopathology wwas the most commonly used diagnostic tool (Table ). Corticosteroids were administered in 27 cases (4%, CI: 2.2-4.8). Thirteen of these cases were diagnosed as MCT and 5 cases were histiocytomas. In 6 cases of MCT and 1 case of malignant melanoma, corticosteroids were given in combination with surgery.
Euthanasia was the final outcome in forty patients (5%, CI: 3.7-6.8) of which 30 had malignant neoplasms, 6 had benign neoplasms and 4 had tumours of unknown biological behaviour.
In cases where the diagnosis was confirmed by histopathology, surgical excision was performed in 97% (CI: 94.7-99.2) of the benign tumours and in 80% (CI: 72.7-88.1) of the malignant ones, whereas in cases where the diagnosis was made by cytology, surgical excision was only performed in 31% (CI: 25.4-36.2) and 52% (CI: 38.9-64.6) of the benign and malignant cases, respectively. The proportion of cases diagnosed by histopathology that had surgical treatment was significantly higher than the proportion of surgical cases diagnosed by cytology (P < 0.0001).
Mast cell tumours
MCT were the most common malignant neoplasms of the skin. A total of 114 MCT were reported, and their grade was reported in 51 cases. The diagnostic tool was cytology in 49 cases and histopathology in 65 cases. Only in two cases another diagnostic tool was chosen. Of the graded cases, 17 were reported as grade I, 26 as grade II and 8 as grade III. MCT were located on the trunk including the inguinal area in 46 cases (40%, CI: 31.4-49.4), in the perineal-genital area in 5 cases (4%, CI: 0.6-8.1) and on the extremities in 23 cases (20%, CI: 12.8-27.5). Surgery was performed in 83 out of the 114 cases (73%, CI: 64.6-81.0) including 34 cases of MCT on the trunk (74%, CI: 61.2-86.6), in 18 cases on extremities (78%, CI: 61.4-95.1) and in 2 cases of perineal-genital sites (40%, CI: 0-83.0). Of the graded cases, grade I MCT were excised in 11 cases (64.7%, CI: 42.0-87.4, of grade I cases), grade II in 25 cases (96.2%, CI: 88.8-100, of grade II cases) and grade III in 2 cases (25%, CII 0-55.0, of grade III cases). The majority of the grade III cases had either corticosteroid therapy (5 cases) or were euthanised (2 cases). In 14 cases of MCT, corticosteroid treatment was given supplementary to surgery. Fifteen cases had regional or distant metastases; of these 10 cases had surgery (Table ).
Distribution of 114 cases of MCT