Prostatic Neoplasia in the Intact and Castrated Dog: How Dangerous is Castration?

SIMPLE SUMMARY: Castration of dogs is a routinely performed surgery to limit unwanted reproduction and prevent pathologies of the genital tract. Over the last two decades, the number of reports on possible long-term health risks has increased. Pet-owners have easier access to scientific publications and are concerned about reports on increased risks of castrated dogs for neoplastic diseases. Divulgation of results without consideration of study design and inclusion criteria for the studied populations may result in premature conclusions impacting many stakeholders. Our aim is to provide a detailed description of prostatic cancer in the dog and the possible side effects of castration. Age at diagnosis ranges from 8.5 to 11.2 years in both intact and castrated dogs. A cytological or histological exam is needed to confirm a suspect. Most dogs already present metastasis at the time of diagnosis which makes prognosis generally poor, also if lung metastasis reportedly has no negative impact on the survival time. Castrated dogs with prostate cancer have been reported to live longer than intact ones. We conclude that until today, we knew too little to exclude routine castration of adult male dogs under six years of age from the veterinary practice due to concerns of causing prostatic neoplasia. ABSTRACT: Elective gonadectomy in the dog is a topic of interest for clinicians, pet-owners, and society. Although canine prostatic neoplasia (CPN) has a low incidence (0.35%), reports of an increased risk for castrated dogs attract attention and cause concern in pet-owners. Our aim is to provide professionals and non-professionals with a detailed description of this possible side effect of gonadectomy in the dog. The mean age at diagnosis of CPN ranges from 8.5 to 11.2 years. Medium to large size breeds are more frequently affected. Symptoms and findings of non-invasive examinations are not pathognomonic, therefore, cytological or histological examinations are needed for diagnosis. Overall, the incidence of metastasis reaches up to 80%, yet lung metastasis reportedly has no negative impact on median survival time (MST). It has been reported that castrated males have a significantly higher MST than intact males. Differences in inclusion criteria for studied populations make a comparison of studies difficult. Citation of odds ratios without consideration of the context of the reference may result in premature conclusions. We conclude that elective gonadectomy of adult male dogs under six years of age cannot be excluded from the veterinary practice due to concern of causing CPN until clear and strong evidence is available.