Neoplasia of the prostate develops uncommonly in dogs. Prostate cancer in dogs is used as a comparative animal model for prostate cancer in men. Prostate tumors have been very rarely reported in cats.
Etiology and Pathophysiology of Neoplasms of the Prostate in Dogs
The etiology of neoplasia of the prostate in dogs is not well-established.
The most common neoplasm of the prostate is carcinoma arising from ductal or urothelial tissue. Transitional cell carcinoma arising from the prostatic urethra occasionally invades the prostate.
Castration does not protect against future development of prostatic neoplasia in dogs, and in fact, prostatic neoplasia incidence is higher in castrated dogs.
Pearls & Pitfalls
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Clinical Findings of Neoplasms of the Prostate in Dogs
Clinical signs of prostatic neoplasia may be similar to those of other prostatic diseases.Pain and fever may be present. If the neoplasm infiltrates the urethra, dysuria or urethral obstruction is likely. On rectal palpation, the prostate may be normal in size but feel asymmetrical and nodular. It may also be firmly adhered to the pelvic floor or adjacent structures.
Gross metastases are present at the time of diagnosis in > 80% of dogs with prostatic carcinoma. The most common sites of metastases are the regional lymph nodes, lumbar vertebrae, and bony pelvis. Spread to distant sites (such as lungs) is uncommon until late in the disease course.
Urethral obstruction caused by prostatic disease in dogs is highly suggestive of neoplasia, as is prostatomegaly in a previously castrated dog.
Diagnosis of Neoplasms of the Prostate in Dogs
Ultrasonographic examination for prostatic neoplasia may show an irregularly shaped prostate gland with hyperechoic, heterogenous foci (see video illustrating transabdominal ultrasonography of the prostate in a dog).
Definitive diagnosis is made by biopsy and histological evaluation. Prostatic tumor markers used for human prostatic cancer, such as prostate-specific antigen and prostatic acid phosphatase, are not present in canine prostate glands.
Treatment of Neoplasms of the Prostate in Dogs
There is no effective curative treatment for prostatic carcinoma in dogs.
Because of the high incidence of metastases at the time of diagnosis and the high incidence of urinary incontinence after prostatectomy in dogs, total prostatectomy is not recommended as a treatment.
Radiation therapy for prostatic cancer often results in incontinence due to radiation-induced fibrosis of the urinary bladder.
Alternative means of ablating prostatic tissue, such as transrectal high-intensity focused ultrasound, transurethral intraprostatic absolute ethanol injections, transurethral laser vaporization, and transurethral electrocoagulation, have been successful in experimental studies but have not been performed on dogs with prostatic carcinoma.
In a study involving 32 dogs with prostatic carcinoma, treatment with the cyclooxygenase inhibitors piroxicam (0.3 mg/kg, PO, every 24 hours) or carprofen (2.2 mg/kg, PO, every 12 hours) significantly prolonged the median survival time of dogs with prostatic carcinoma compared with dogs not receiving treatment (6.9 vs 0.7 months) (1).
Key Points
Prostatic neoplasia is the most common prostatic problem in castrated dogs.
Affected dogs develop dysuria and/or tenesmus as well as clinical signs associated with metastasis to regional lymph nodes, lumbar vertebrae, and bony pelvis.
No curative treatment exists for prostatic neoplasia in dogs.
Treatment modalities include surgery, chemotherapy, radiation therapy, and cyclooxygenase inhibitors (ie, NSAIDs).
For More Information
Palmieri C, Fonseca-Alves CE, Laufer-Amorim R. A review on canine and feline prostate pathology. Front Vet Sci. 2022;9:881232.
Gibson EA, Culp WTN. Canine prostate cancer: current treatments and the role of interventional oncology. Vet Sci. 2024;11(4):169.
Urlings P, Gramer I, Jones C, Dirrig H. Computed tomographic features of canine prostatic carcinoma. Vet Radiol Ultrasound. 2024;65(4):447-455.
Also see pet owner content regarding prostatic diseases in dogs.
References
Sorenmo KU, Goldschmidt MH, Shofer FS, Goldkamp C, Ferracone J. Evaluation of cyclooxygenase-1 and cyclooxygenase-2 expression and the effect of cyclooxygenase inhibitors in canine prostatic carcinoma. Vet Comp Oncol. 2004;2(1):13-23. doi:10.1111/j.1476-5810.2004.00035.x
