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PROSTATIC carcinomas are malignant neoplasms with a reported incidence in male dogs of 0.2–0.6 per cent based on postmortem examination studies (Bell and others 1991). Unfortunately, dogs often present late in the course of disease due to rapid tumour growth and distant metastasis (Waters and Bostwick 1997). Primary clinical signs are often associated with the local effects of the tumour, with up to 40 per cent of dogs developing dysuria (Bell and others 1991). A study involving 76 dogs reported urinary problems (e.g. stranguria, haematuria, incontinence) and faecal tenesmus in 62 per cent and 30 per cent of cases, respectively (Cornell and others 2000). In both studies, dysuria and dyschezia were attributed to physical blockage by an enlarged prostate (Bell and others 1991, Cornell and others 2000). Urethral obstruction is a veterinary emergency due to risk of renal failure and bladder rupture. Surgical methods of addressing any physical blockage are available, but the outcome is variable. Complete prostatectomy is associated with incontinence, disease recurrence and short postsurgery survival times (STs) (Hardie 1984, Vlasin and others 2006). Palliative urethral stents have been placed to alleviate obstructions secondary to prostatic disease; however, poor outcomes have been documented anecdotally by the authors. In a previous study, metallic stents were placed in dogs affected with prostatic carcinoma (n=7), transitional cell carcinoma (n=4) and prostatic osteosarcoma (n=1). Complications including reobstruction were noted in 5/12 animals. Within the prostatic carcinoma group, four dogs retained a degree of poststent stranguria and one dog required restenting due to reobstruction (Weisse and others 2006). More recently, urethral stents were placed in dogs affected with obstructive carcinoma of the urethra (including prostatic carcinoma), leading to severe incontinence in 26 per cent of patients (Blackburn and others 2013).
Based on their clinical observations, the authors hypothesise that a …