Disorders of the Prostate

26 Disorders of the Prostate




FREQUENTLY ASKED QUESTIONS



1) My male has been diagnosed with benign prostatic hypertrophy (BPH). Does he have to be castrated?

No medical therapy has been demonstrated to be as effective for decreasing clinical signs of BPH and prostate size as castration. I usually recommend medical therapy be used until you have the breedings you want from that male or have collected and frozen semen. Castration should be performed at some point.


2) How does prostate infection cause a decline in semen quality?

That is a good question. In some dogs there probably is a certain degree of infection or inflammation throughout the reproductive tract, including the prostate and testes. In other dogs it is thought that the abnormal prostatic fluid, which is all the fluid portion of the ejaculate, alters the morphology and motility of spermatozoa as they are ejaculated and intermingle.


The prostate encircles the neck of the urinary bladder such that the urethra runs directly through the center. There are two prostatic lobes, separated by fibrous tissue. Growth and function of the prostate are androgen dependent. Under the influence of testosterone and its metabolite, dihydrotestosterone (DHT), prostatic cells increase in number (hyperplasia) and size (hypertrophy). As long as a male dog is intact, progressive increase in prostate size will occur. Castration causes profound prostate atrophy.


The following are diagnostic tests used for identification of all types of prostatic disease:


• Rectal palpation of the prostate to determine size, symmetry, and pain response.

• Collection of semen for cytology and culture. The fluid portion of semen is secreted by the prostate gland.

• Imaging of the prostate. Ultrasound is most commonly performed because it allows identification of abnormalities within the prostate tissue and can be used to guide aspiration or biopsy of the prostate (Figure 26-1). Plain radiographs do not allow accurate assessment of prostate size. Infusion of contrast medium, which appears very white on radiographs, into the urethra and urinary bladder may better allow definition of prostate disease.

• Aspiration or biopsy of the prostate with submission of samples collected for cytology and culture. This usually is done with ultrasound guidance (Figure 26-2). Aspiration of the prostate does not require sedation; collection of a biopsy specimen does require sedation of the dog.

• Measurement of secretory proteins is not performed in dogs as it is in men with prostate disease. In men concentrations of prostate specific antigen (PSA) can be used to diagnose disease, to assess the efficacy of treatment, and to determine prognosis. Measurement of PSA and other secretory proteins has not been proven useful in veterinary medicine.

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Figure 26-1 Performance of prostatic ultrasound.


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Figure 26-2 Performance of ultrasound-guided aspirate of the prostate.



I. BENIGN PROSTATIC HYPERTROPHY/HYPERPLASIA



A. DEVELOPMENT


Benign prostatic hypertrophy/hyperplasia (BPH) is an androgen-dependent increase in cell number and size. This is an age-related phenomenon; by 5 years of age, all intact male dogs have some degree of BPH, the most common prostatic disorder diagnosed in dogs.



B. SIGNALMENT


BPH may occur in young dogs, but it is much more common in older males. There is no breed predisposition reported in dogs for this condition. BPH only occurs in intact males.



C. HISTORY AND CLINICAL SIGNS


Dogs may have evidence of BPH that can be identified on radiographs or on physical examination and exhibit no clinical signs of disease. If there is clinical evidence of BPH, the most common manifestation is dripping of bloody fluid from the tip of the penis unassociated with urination. This clinical sign may be evident only when the male is exposed to an estrous female, causing prostatic contractions. The enlarged prostate gland has an excellent blood supply, and the bloody prostatic fluid runs into the bladder as well, giving the appearance of bloody urine (hematuria). As the enlarged prostate presses up against the colon, straining to defecate or passage of ribbon-like feces may be seen. The dog feels well otherwise.



D. DIAGNOSIS


Diagnosis may be made based solely on rectal palpation of the prostate and submission of semen for cytology and culture. Semen color may be abnormal (Figure 26-3). Imaging and aspiration of the prostate may be performed (Figure 26-4 and Table 26-1).


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Figure 26-3 Variations in semen color in dogs with benign prostatic hyperplasia.


(Courtesy Dr. Kaitkanoke Sirinarumitr.)


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Figure 26-4 Ultrasound from dog with benign prostatic hyperplasia.


Table 26-1 Diagnostic Test Results in Dogs with Benign Prostatic Hyperplasia


















Diagnostic Test Result and Interpretation
Rectal palpation Symmetrical, nonpainful. The prostate may be so enlarged as to pull the urinary bladder into the abdomen. The enlarged prostate may be palpable per abdomen.
Semen collection Color of prostatic fluid varies from clear to tan to maroon (Figure 26-3).
Prostatic radiographs or ultrasound Contrast radiographs demonstrate forward movement of the bladder and flattening of the back of the usual teardrop-shaped urinary bladder by presence of the enlarged prostate. On ultrasound, the prostatic tissue is uniform (Figure 26-4).
Aspirate or biopsy Normal cells are present. There are no inflammatory changes.


E. TREATMENT


In dogs with no clinical signs of disease, no treatment may be necessary. If treatment is required, castration is the best therapy, causing the quickest and most complete prostate atrophy. If castration is undesirable, medical therapy with the human drug finasteride (Proscar or Propecia) may be used to decrease prostate size. Finasteride is administered daily for 1 to 4 months. A significant decrease in prostate size and coincident clinical signs occurs within 4 to 6 weeks of therapy in most dogs. After withdrawal of the drug, the prostate gradually will increase in size again. Treatment of dogs with finasteride is not associated with decline in semen quality. Breeding of dogs on finasteride has not been associated with small litter size or induction of birth defects in pups. Other therapies described for use in humans, such as the use of the herb saw palmetto, have not been demonstrated to be useful therapies for BPH in dogs. Other hormone therapies, including use of progesterone or estrogen, have been described for use in dogs but may have undesirable side effects.



F. PROGNOSIS


Dogs with BPH generally have normal semen quality. The presence of blood in the ejaculate (hemospermia) does not appear to alter fertility for natural service or artificial insemination with fresh semen. Semen containing blood is unsuitable for use as chilled or frozen semen; even after centrifugation of the sample to remove the spermatozoa from the bloody fluid, the spermatozoa do not tolerate the chilling or freezing process well. The presence of BPH predisposes the dog to prostate infection, which can alter semen quality.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Disorders of the Prostate

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