Brandan G. Wustefeld‐Janssens

Apocrine gland anal sac adenocarcinoma (AGASACA) is a highly relevant disease in dogs, with a high rate of lymph node (LN) metastasis during the course of disease. A recent study showed that risk for death and disease progression was significantly associated with primary tumour size less than 2 and 1.3 cm, respectively. The objective of this study was to report the proportion of dogs that have primary tumours less than 2 cm in diameter, that are diagnosed with LN metastasis at presentation. This was a single site retrospective study of dogs that underwent treatment for AGASACA. Dogs were included if physical examination primary tumour measurements were available, abdominal staging was performed, and confirmation of abnormal lymph nodes by cytology or histology was done. Over a 5‐year period, 116 dogs were included for review with 53 (46%) having metastatic LN at presentation. The metastatic rate for dogs with primary tumours <2 cm was 20% (9 of 46 dogs) compared to 63% (44 of 70 dogs) in dogs with primary tumours ≥2 cm. The association between tumour size group (<2 vs. ≥2 cm) and the presence of metastasis at presentation was significant ( P < .0001) with an OR of 7.0 (95% CI: 2.9–15.7). Primary tumour size was significantly associated with LN metastasis at presentation but the proportion of dogs that presented with LN metastasis in the <2 cm group was relatively high. This data suggests that dogs with small tumours may still have aggressive tumour biology.

Surgical resection of solid tumours, especially in early stages of disease, remains a cornerstone of cancer treatment in dogs and cats. There are numerous publications that show a strong association between local tumour control and outcome. To achieve local control in some cases radiation therapy and surgery are combined, with radiation therapy being delivered in the neoadjuvant or adjuvant setting. The objective of the study was to report acute toxicity and surgical site complication data in dogs that received a short‐course pre‐operative (SCPO) radiation therapy protocol, followed by surgical excision for various solid tumours. Medical records were reviewed, and data was analysed retrospectively. Dogs were included if a dermal or subcutaneous solid tumour was treated with SCPO radiation therapy and then was resected on the last day of radiation or 2–3 weeks later. A total of 34 dogs with 35 primary tumours were included. Acute radiation toxicity was diagnosed in 14 sites (40%). VRTOG scores were grade 1 in 50%, grade 2 in 43%, and grade 3 in 7%. Surgical site complications were identified in 17% of dogs with an overall surgical site infection rate of 11%. According to the Clavien‐Dindo classification, two dogs required medical intervention (grade 2), 1 dog required surgical intervention under general anaesthesia (grade 3b), and 1 dog died as a result of complications (grade 5). Logistic regression analysis found that anatomic site was significantly associated with complications, where tumours located on the extremity was protective ( P = .02; OR 0.06).