Peter E. Holt, BVMS, PhD, ILTM, DECVS, CBiol, FIBiol, FRCVS
Professor of Veterinary Surgery, University of Bristol, Department of Clinical Veterinary Science
Langford, Bristol, UK
Problems affecting the canine prostate include benign enlargement (hyperplasia/metaplasia), prostatitis (acute or chronic), abscessation, prostatic cysts, neoplasia, idiopathic haemorrhage and displacement into ruptures or hernias.
The clinical signs in dogs with prostate disease include haematuria, dysuria, urinary incontinence, dyschezia, pain and weight loss. These signs are not pathognomonic and so must be differentiated from similar signs due to non-prostatic disorders. Once it is determined that the signs are associated with a prostatic condition, the nature of that condition should be determined. Useful differential features are that only acute prostatitis (+ abscessation) and neoplasia are painful conditions; prostatic abscesses, cysts and tumours result in asymmetrical prostatic enlargement; in some dogs with prostatic tumours a small, painful prostate is present. Prostate cancer is also one of the few prostate conditions to affect castrated dogs. Indeed, some authors believe prostate cancer to have a higher prevalence in castrated versus entire animals.
Apart from clinical examinations, useful investigative techniques include contrast radiography (especially retrograde positive contrast urethrocystography), ultrasonography, fine needle aspirates and biopsies, cytology and histology.
Prostatic hyperplasia responds to oestrogen (or anti-androgen) therapy and more permanently, to castration. Prolonged oestrogen therapy is contra-indicated since squamous metaplastic prostatic enlargement may result. Most prostatic tumours are malignant and the prognosis is hopeless; prostatectomy is not to be recommended in the author's view although some palliation may be obtained in some animals with non-steroidal antiinflammatory drugs. Mild prostatitis may respond to antibiotics and castration but abscesses and cysts require surgical drainage. The prognosis associated with prostatic cysts and abscesses is guarded and no one form of treatment (marsupialisation, drainage procedures, partial or complete prostatectomy) is 100% successful. Omentalisation of prostatic abscesses has been used with good results (White & Williams, 1995). This may be combined with partial resection of the prostate (Bray et al, 1997). See Holt and White (2000) for a review of the treatment of prostatic cysts and abscesses. A biopsy should always be taken during surgery since a proportion of prostatic cysts and abscesses have a carcinoma of the lining.
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2. Caney, S.M.A., Holt, P.E., Day, M.J., Rudorf, H. & Gruffydd-Jones, T.J. (1998). Prostatic carcinoma in two cats. J. small Anim. Pract. 39, 140-143.
3. Holt, P.E. (1994). A Color Atlas and Text of Small Animal Urology. Mosby-Wolfe, London.
4. Holt, P.E. & White, R.A.S. (2000). Prostatic cysts and abscesses in the dog: treatment options. Veterinary International 12, 11-18.
5. Mullen, H.S. et al (1990). Results of surgery and postoperative complications in 92 dogs treated for prostate abscessation by a multiple Penrose drain technique. J. Am. Anim. Hosp. Ass. 26, 369-379.
6. Weaver, A.D. (1977). Transperineal punch biopsy of the canine prostate gland. J. Small Anim. Pract. 18, 573-577.
7. White, R.A.S. & Williams, J.M. (1995). Intracapsular prostatic omentalisation: a new technique for management of prostatic abscesses in dogs. Vet. Surg. 24, 390-395.