Abstract
Background:
Canine prostatic carcinoma (PC) is an uncommon neoplasia characterized by an aggressive biological behaviour. Treatment options include surgery (partial or total prostatectomy), radiation therapy (RT), and medical treatment (NSAIDs, chemotherapy or tyrosine kinase inhibitors). Electrochemotherapy (ECT) is a local treatment modality increasingly used in human and veterinary oncology.

Aim:
This retrospective multi- institutional study aimed to assess the safety, feasibility and preliminary efficacy of ECT as a treatment for canine PC.

Methods:
Dogs with a cytologically or histologically confirmed PC treated with ECT as first line therapy were included. Dogs with distant metastases or previously treated with surgery, RT or chemotherapy were excluded. Clinical response was evaluated based on improvement of clinical signs and reduction in tumour volume. Adverse effects, time to progression (TTP), and median survival time (MST) were recorded.

Results:
Nine dogs were enrolled. All but two dogs were neutered. Regional lymph node metastases were present in two cases (22%). In one patient, metastatic lymph nodes were treated concurrently with ECT. Three patients (33%) had a partial response, three (33%) had stable disease, 2 (22%) had progressive disease, and one complete response. Overall response rate, including complete and partial response, was 44%. Median TTP was 74 days and MST was 70 days. The treatment was well tolerated, with no local or systemic adverse effects observed.

Conclusion:
This preliminary study showed that ECT is a safe and well tolerated local therapy, although survival outcomes were modest compared to surgery, RT or medical treatment. Further controlled, prospective studies are needed to better define its role as a therapeutic option.

Key words: Dog; Electrochemotherapy; Prostatic carcinoma; Safety; Treatment.