Epidemiology of testicular tumour diagnoses in Australian dogs in primary care (1992-2022): A retrospective analysis of electronic patient records.

Abstract

Canine testicular tumours are among the most common reproductive tract tumours in male dogs, particularly affecting older, intact males. Globally, studies have examined their incidence, histological types and associated risk factors, with particular attention given to cryptorchidism and breed predisposition. Despite extensive international research, the epidemiology of testicular tumours in the Australian canine population remains largely unknown. This study aims to characterise the overall occurrence, potential demographic factors and spatial distribution of testicular tumours in Australian pet dogs. Data were sourced from VetCompass Australia, a comprehensive database which collates medical consultation records and demographic information on dogs attending general veterinary practices across Australia. The study included dogs under primary veterinary care from 1992 to 2022. Using specific keywords, patient files with possible testicular tumours were identified and confirmed through manual review of histopathological diagnoses. The association between potential variables and types of testicular tumours was analysed using Pearson's chi-squared test in R. Geographic distribution was visualised using ArcGIS mapping software. Testicular tumours were diagnosed in 333 canine subjects for a total of 351 tumours. The tumour types included: 115 seminomas, 113 Sertoli cell tumours, 76 interstitial cell tumours, 40 mixed germ cell-sex cord stromal tumours, and 7 mixed sex cord stromal tumours. Among the 333 dogs, 49 had bilateral tumours, 215 unilateral tumours and 75 unknown laterality. Testicular tumours were detected in 144 left testicles and 143 right testicles. The three purebreds most commonly diagnosed with testicular tumours were Golden Retriever (41.9&#xa0;%), Staffordshire Bull Terrier (28.4&#xa0;%), and German Shepherd (23&#xa0;%). The mean age at diagnosis was 10.2&#xa0;years. Geographically, Queensland recorded the highest number of cases (43.9&#xa0;%) among the Australian states and territories. Cryptorchidism was present in 17.4&#xa0;% of cases and a statistically significant association was found between cancer type and the presence of cryptorchidism, with over-representation of Sertoli cell tumours and seminomas in cryptorchid animals (p&#xa0;<&#xa0;0.05). There was no statistical association between tumour type and age group, breed and geographic location. In conclusion, this study provides the first large-scale epidemiological overview of the occurrence of canine testicular tumours in Australian dogs. A more in-depth exploration of the interplay between environmental and demographic factors will enhance our understanding and inform strategies for prevention, early detection, and treatment of testicular tumours in dogs.