The canine prostate is a secondary-sex organ and neuroendocrine gland which produces ejaculate as part of sexual reproduction and responds to somatic sexual arousal via the central nervous stimulation.
The size and weight of the prostate vary depending on the age, breed, and body weight of the dog. The first histological signs of activity appear at about four months of age, and prostatic acinar cells become periodic acid-Schiff (PAS)-positive at twenty-four weeks of age, suggesting the beginning of secretory activity.
Because the canine prostate is bilobed with a prominent medium septum but is without zonal structures and has a fibromuscular capsule surrounding the corpus prostate (body). The prostate capsule acts similar to the blood-brain barrier, penetration of the prostatic capsule with antimicrobials, chemotherapy and other therapeutic medicines can be prolonged and difficult.
Additional to this is the fact that the prostate has limited expansile properties, and various diseases such as infections and neoplasms invariably is limited to chronic expansion which occurs over many weeks. Prostate-associated pain is usually low-grade due to intraprostatic pressure which is alleviated by gradual expansion of the fibromuscular capsule.
Cell proliferation and differentiation of the prostatic epithelium are controlled primarily by androgens, the most potent of which is testosterone. Testosterone is converted to the most potent dihydrotestosterone by 5alpha-reductase within the prostate. Androgen interacts with androgen receptors to regulate normal growth of the prostate and has also been implicated in both the progression of benign prostate hyperplasia and prostate cancer in dogs.
The canine prostate also has receptors for leutinizing hormone and follicle stimulating hormone, and actively responds to these hormones at differing times related to seasonal changes and female estrus cycles. Androgens are critical in prostate development during puberty, as well as disease development, especially prostatic hyperplasia.
Normal dog urine usually contains traces of prostatic antigens, similar to human prostatic antigens used to assess prostatic carcinoma. One antigen in dog urine, prostatic lallikrein is identical to that found in dog dander, and is highly allergic, but its clinical relevance is currently unknown.
Bacterial infection, endocrine influence, immunological dysfunction and stress are reported to be factors in development of prostatic inflammation.
Diseases of the prostate include:
- Congenital diseases
- - Hypospadias - prostate absence
- - Persistent Müllerian duct syndrome - Miniature Schnauzer predisposition
- Prostatic atrophy - associated with increased collagen deposition
- Prostatic abscess
- Transmissible venereal tumor
- Urolithiasis or urethral trauma
- - prostatic adenocarcinoma
- - Prostatic hyperplasia - usually older dogs
- - Prostatic squamous metaplasia
- - Prostatic adenocarcinoma
- - Prostatic lymphoma
- Miscellaneous causes
Additional clinical signs such as fever, malaise, caudal abdominal pain, incontinence and anorexia are often indicative of bacterial infections or neoplasia.
Although prostatic diseases may occur in young dogs, older entire dogs are commonly affected with less serious conditions such as benign prostatic hyperplasia.
Interestingly, although benign prostatic hyperplasia is uncommon in neutered male dogs, the risk of developing prostate cancers, particularly prostate adenocarcinoma, transitional cell carcinoma and carcinoma is higher in this group.
Diagnosis of prostatic disease should be undertaken step-wise, commencing with routine hematology and biochemistry, rectal palpation of the prostate gland, ultrasonography, and radiographic, CT or MRI imaging studies.
Collection of urine and culturing for bacteria, fungi and detection of neoplastic cells is mandatory for a full diagnostic workup.
Definitive diagnosis usually requires fine-needle percutaneous, laparoscopy-guided or surgical biopsy of the prostate.
In non-metastatic prostatic diseases, prostatectomy should be considered a safe surgical procedure with good curative rates despite its technical challenges.
- University of Guelph
- University of Guelph
- Ireland Veterinary Journal
- University of Lisbon
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