Prostatic Disorders
Diseases of the prostate occur commonly in dogs, and Doberman Pinschers reportedly having an increased risk compared to other breeds. The prostate gland is a solid organ that surrounds the base of the urethra in males and is responsible for producing some of the fluid found in the semen.
Benign Prostatic Hyperplasia
Cause: Benign prostatic hyperplasia (BPH) occurs as an aging change in intact male dogs. Studies suggest that increasing levels of estrogen associated with age result in an increase in androgen receptors on the surface of prostate cells. When these receptors bind to circulating androgen, a hormone produced by the testes, this reaction stimulates the glandular prostate cells causing them to grow and divide. Glandular hyperplasia may begin as early as 2.5 years in some dogs and by 6 years of age it is estimated that 60% of intact males have BPH; by 9 years this estimate increases to 95%.
Symptoms: Most dogs with BPH will have no symptoms or evidence of systemic illness. Occasionally, some males may develop difficulty to urinate or defecate if the enlarged prostate places pressure on the urethra or the descending colon, respectively. In other dogs, blood in the urine or a blood-tinged ejaculate for semen analysis may be the only indication of BPH.
Diagnosis: Physical examination of the prostate by rectal exam will reveal enlargement of the prostate gland, though texture and consistency will feel like a normal prostate. Usually the enlarged gland is not painful unless bacterial infection is also present. Though radiographs and ultrasound will confirm enlargement of the prostate, these methods do not offer a definitive diagnosis because other prostatic disorders may appear similar by imaging. A definitive diagnosis is best accomplished through ultrasound-guided needle biopsy to obtain a sample of prostate tissue for histopathologic analysis. Alternatively, serum analysis for elevated levels of canine prostate specific esterase (CPSE), an enzyme marker that appears to be specific for BPH over other prostatic disorders, may provide diagnostic information.
Treatment and Prognosis: Asymptomatic dogs with BPH usually do not require treatment. When symptoms become apparent, castration is the most successful form of treatment and results in rapid regression of the prostate size. Alternative treatments to surgery include the following:
Drug Properties Indications Contraindications Effects on Breeding
Estrogen
(diethylstilbestrol) Reduces androgen concentration by inhibiting gonadotropin secretion by the pituitary gland Decreases prostate size by decreasing cellular mass anemia, immunosuppression associated with repeated administration. Long-term use will increase prostate size and predispose to prostatic cysts, bacterial infections, and abscesses short-course therapy reduces prostatic secretory capability for 2 months
Dihydrotestosterone (DHT) Receptor blockers (anti-androgen flutamide) blocks DHT (produced from testosterone) activity by competing for DHT receptors Decreases prostate size in dogs within 10 days to 6 weeks of treatment prostatic hyperplasia recurs within 2 months if treatment stopped. Not approved for veterinary use/ expensive. No effects on libido, sperm production or fertility in dogs.
Progestins (Megestrol acetate) reduces serum testosterone concentration, inhibit DHT receptor binding, decreases DHT levels, and decreases the number of androgen receptors reduces prostate size and eradicates associated symptoms relapse in 10 to 24 months when treatment discontinued. No long-term studies on side effects on the dog. Not approved for use in males (approved use in bitches for other conditions restricted to 32 days) No effects on sperm or fertility. May help to maintain short period of breeding soundness in BPH males prior to neutering.
5-alpha-reductase inhibitors (Finasteride) blocks DHT production from testosterone 20-30% reduction in prostate size in men for 6-12 months potentially teratogenic (biologically hazardous to developing fetuses) no effects on libido or semen production but can cause fetal genetic anomalies and is present in semen of treated patients (not recommended for use in breeding males)
antifungal drugs (ketoconazole and gonadotropin releasing hormone analogs block release of lutenizing hormone reduces prostate size known as "chemical castrators" results similar to surgical castration (not recommended for breeding males)
Prostatitis
Cause: When bacterial infection occurs concurrently with benign prostatic hyperplasia (BPH), the condition is known as prostatitis. Prostatitis occurs when bacteria that normally inhabit the male urethra ascend into the prostate gland. Conditions of BPH predispose the prostate to infection because this disorder creates an environment suitable for bacterial proliferation. Common organisms identified in causing prostatitis include: Escherichia coli, Staphylococcus aureus, Klebsiella spp., Proteus mirabilis, Mycoplasma canis, Pseudomonis aeruginosa, Enterobacter spp., Streptococcus spp., Pasteurella spp., and Haemophilis spp.. Though Brucella canis may infect the prostate, it more commonly infects testicular tissue. Fungal infections are less common but occasionally occur. In some instances, testicular infections may spread to the prostate. Prostatitis is the most common prostatic disorder occurring in intact male dogs. In some dogs, particularly those over 5 years of age, prostatitis leads to the formation of abscesses within the prostate. Prostatitis is rare in castrated males.
Symptoms: Prostatitis may occur as an acute or chronic condition. In the acute phase, fever and lethargy are present, the dog may strain when urinating or defecating, and the dog may move with a stiff gait. Swelling of the scrotum and hindlimbs may also be observed. Dogs that have prostatic abscessation may present with symptoms of shock (rapid heartbeat [tachycardia], delayed capillary refill time, pale or muddy mucus membranes, weak pulse, vomiting), peritonitis, and systemic infection (sepsis) if the abscess ruptures. Chronic prostatitis may occur following an acute phase or may develop without symptoms. Evidence suspicious of chronic prostatitis includes poor semen quality, decreased libido associated with pain upon prostatic contraction during ejaculation, and blood in the urine or semen sample.
Diagnosis: In acute cases of prostatitis, findings of an enlarged and/or painful prostate upon examination and evidence of bacteria in the urine of the dog, are highly indicative of this condition. A culture and sensitivity of urine removed from the bladder by cystocentesis is helpful for identifying the causative bacterial organism. Pain usually impedes the process of obtaining a prostatic fluid sample from the patient. Additionally, manipulation of the prostate should be avoided to prevent further spread of bacterial infection. In chronic cases, the prostate gland is typically painless or not as painful as in acute cases. This allows for collection of prostatic fluid for bacterial analysis since bacteria are not always found in the urine of dogs suffering from chronic prostatitis. Radiographic and ultrasonographic changes in the prostate are often apparent in dogs with chronic prostatitis. In cases where prostatic fluid culture does not identify an infectious organism, but diagnostic imaging is indicative of disease, biopsy of the prostate tissue will confirm a diagnosis of prostatitis.
Treatment and Prognosis: Aggressive treatment of acute prostatitis may prevent the infection from developing into chronic prostatitis. Results from urine culture and sensitivity screening will assist the clinician in selecting an antimicrobial drug with low potential for microorganism resistance and ability to maintain therapeutic concentrations in the urine and tissues. The anti-microbial agent is administered for at least 3-4 weeks to ensure complete elimination of the infection. Additionally, it is recommended that urine cultures and prostatic fluid cultures be analyzed 7-10 days after completion of drug therapy to ensure eradication of the infectious organisms. When treated aggressively and thoroughly, acute prostatitis is expected to have a good prognosis for recovery.
Chronic prostatitis is more challenging to treat and treatment difficulties are compounded by the fact that many anti-microbial drugs cannot efficiently cross the prostatic tissues and enter the prostatic fluid. Some anti-microbial agents are more soluble than others are and these are most effective for the treatment of chronic prostatitis. Such agents include: chloramphenicol, erythromycin, trimethoprim, ciprofloxacin, enrofloxacin, and carbenicillin. Therapy is typically continued for 4-6 weeks. Following completion of drug treatment, urine and prostatic fluid culture is performed at 4-7 days and 30 days following completion of treatment to ensure elimination of the infection. In many cases, follow-up culture indicates insufficient resolution of the infection by the first treatment regimen and a 3-month course of antibiotics with adjuvant therapy (hormone therapy or castration) to reduce concurrent prostatic hyperplasia is prescribed. Should this latter approach fail to eradicate infection, chronic low-dose antimicrobial therapy or prostatectomy are options to consider. Prognosis for chronic prostatitis is fair considering the limitations to therapy with antimicrobials against this disease and thus, the high incidence for relapse.
Cancer of the Prostate
Cause: Prostate cancer (prostatic adenocarcinoma [PAC]) is an uncommon disease in dogs but occurs with highest incidence in 8-10 year old intact and castrated males. In fact, risk of prostate cancer in early castrated males is equal to if not slightly higher than in intact males. This may be associated with the observation that castrated males usually do not manifest concurrent hyperplastic changes in the prostate as do intact males and thus maintain smaller tumor masses that may go undetected for longer periods of time allowing for a more invasive tumor phenotype to develop. Unlike human prostate cancer in which androgens appear to contribute significantly to neoplastic development, prostate cancer in dogs appears to be androgen independent. It is speculated, therefore, that early testosterone effects or nontesticular androgens of adrenal origin may play a role in the development and progression of prostate cancer in dogs.
Symptoms: Dogs with PAC develop symptoms consistent with enlargement of the prostate: difficulty urinating and/or defecating. Many dogs will also demonstrate anorexia and weight loss. Bone pain, an indication of tumor cell metastasis (spread) to the bone, may occur predominantly in the lower back and is a sign of late stage disease.
Diagnosis: In geriatric males, enlargement of the prostate in an intact male or a normal-sized prostate in a neutered male (since castration leads to complete atrophy of prostatic tissue) are suspicious for and highly suspected for PAC, respectively. Ultrasound-guided needle-core biopsy provides the best method for acquiring a definitive diagnosis of PAC and allows for evaluation of tumor grade, a clinical criteria that will assist in determining treatment options and prognosis.
Treatment and Prognosis: Tumors assessed as well-differentiated (closely resembling normal prostate cells) at the time of biopsy may indicate a better prognosis in terms of survival time. Unfortunately, however, PAC is often not diagnosed until the dog is in late stage of the disease when therapeutic options are limited and thus prognosis is considered poor. Surgery to remove the prostate is one possible option for therapeutic management of PAC and if the disease is detected in an early stage, this option may be curative. However, prostectomy is a difficult surgery and is associated with a chronic condition of urinary incontinence. Palliative treatment for PAC includes castration or hormonal therapy with Megestrol acetate or Finasteride to reduce concurrent prostatic hyperplasia and thus alleviate symptoms associated with prostate enlargement. For both intact and castrated males with PAC, external beam radiation therapy may induce temporary regression of the tumor and provide relief of symptoms. Administration of stool softeners may also provide some relief for constipation and because many PAC dogs will have secondary complications associated with bacterial infections, continuous antibiotic therapy may assist in controlling related symptoms. Despite therapeutic intervention with radiation or combination of radiation and chemotherapy, once diagnosis is made, survival time for dogs with PAC does not typically extend beyond 5 months.
Diseases of the prostate occur commonly in dogs, and Doberman Pinschers reportedly having an increased risk compared to other breeds. The prostate gland is a solid organ that surrounds the base of the urethra in males and is responsible for producing some of the fluid found in the semen.
Benign Prostatic Hyperplasia
Cause: Benign prostatic hyperplasia (BPH) occurs as an aging change in intact male dogs. Studies suggest that increasing levels of estrogen associated with age result in an increase in androgen receptors on the surface of prostate cells. When these receptors bind to circulating androgen, a hormone produced by the testes, this reaction stimulates the glandular prostate cells causing them to grow and divide. Glandular hyperplasia may begin as early as 2.5 years in some dogs and by 6 years of age it is estimated that 60% of intact males have BPH; by 9 years this estimate increases to 95%.
Symptoms: Most dogs with BPH will have no symptoms or evidence of systemic illness. Occasionally, some males may develop difficulty to urinate or defecate if the enlarged prostate places pressure on the urethra or the descending colon, respectively. In other dogs, blood in the urine or a blood-tinged ejaculate for semen analysis may be the only indication of BPH.
Diagnosis: Physical examination of the prostate by rectal exam will reveal enlargement of the prostate gland, though texture and consistency will feel like a normal prostate. Usually the enlarged gland is not painful unless bacterial infection is also present. Though radiographs and ultrasound will confirm enlargement of the prostate, these methods do not offer a definitive diagnosis because other prostatic disorders may appear similar by imaging. A definitive diagnosis is best accomplished through ultrasound-guided needle biopsy to obtain a sample of prostate tissue for histopathologic analysis. Alternatively, serum analysis for elevated levels of canine prostate specific esterase (CPSE), an enzyme marker that appears to be specific for BPH over other prostatic disorders, may provide diagnostic information.
Treatment and Prognosis: Asymptomatic dogs with BPH usually do not require treatment. When symptoms become apparent, castration is the most successful form of treatment and results in rapid regression of the prostate size. Alternative treatments to surgery include the following:
Drug Properties Indications Contraindications Effects on Breeding
Estrogen
(diethylstilbestrol) Reduces androgen concentration by inhibiting gonadotropin secretion by the pituitary gland Decreases prostate size by decreasing cellular mass anemia, immunosuppression associated with repeated administration. Long-term use will increase prostate size and predispose to prostatic cysts, bacterial infections, and abscesses short-course therapy reduces prostatic secretory capability for 2 months
Dihydrotestosterone (DHT) Receptor blockers (anti-androgen flutamide) blocks DHT (produced from testosterone) activity by competing for DHT receptors Decreases prostate size in dogs within 10 days to 6 weeks of treatment prostatic hyperplasia recurs within 2 months if treatment stopped. Not approved for veterinary use/ expensive. No effects on libido, sperm production or fertility in dogs.
Progestins (Megestrol acetate) reduces serum testosterone concentration, inhibit DHT receptor binding, decreases DHT levels, and decreases the number of androgen receptors reduces prostate size and eradicates associated symptoms relapse in 10 to 24 months when treatment discontinued. No long-term studies on side effects on the dog. Not approved for use in males (approved use in bitches for other conditions restricted to 32 days) No effects on sperm or fertility. May help to maintain short period of breeding soundness in BPH males prior to neutering.
5-alpha-reductase inhibitors (Finasteride) blocks DHT production from testosterone 20-30% reduction in prostate size in men for 6-12 months potentially teratogenic (biologically hazardous to developing fetuses) no effects on libido or semen production but can cause fetal genetic anomalies and is present in semen of treated patients (not recommended for use in breeding males)
antifungal drugs (ketoconazole and gonadotropin releasing hormone analogs block release of lutenizing hormone reduces prostate size known as "chemical castrators" results similar to surgical castration (not recommended for breeding males)
Prostatitis
Cause: When bacterial infection occurs concurrently with benign prostatic hyperplasia (BPH), the condition is known as prostatitis. Prostatitis occurs when bacteria that normally inhabit the male urethra ascend into the prostate gland. Conditions of BPH predispose the prostate to infection because this disorder creates an environment suitable for bacterial proliferation. Common organisms identified in causing prostatitis include: Escherichia coli, Staphylococcus aureus, Klebsiella spp., Proteus mirabilis, Mycoplasma canis, Pseudomonis aeruginosa, Enterobacter spp., Streptococcus spp., Pasteurella spp., and Haemophilis spp.. Though Brucella canis may infect the prostate, it more commonly infects testicular tissue. Fungal infections are less common but occasionally occur. In some instances, testicular infections may spread to the prostate. Prostatitis is the most common prostatic disorder occurring in intact male dogs. In some dogs, particularly those over 5 years of age, prostatitis leads to the formation of abscesses within the prostate. Prostatitis is rare in castrated males.
Symptoms: Prostatitis may occur as an acute or chronic condition. In the acute phase, fever and lethargy are present, the dog may strain when urinating or defecating, and the dog may move with a stiff gait. Swelling of the scrotum and hindlimbs may also be observed. Dogs that have prostatic abscessation may present with symptoms of shock (rapid heartbeat [tachycardia], delayed capillary refill time, pale or muddy mucus membranes, weak pulse, vomiting), peritonitis, and systemic infection (sepsis) if the abscess ruptures. Chronic prostatitis may occur following an acute phase or may develop without symptoms. Evidence suspicious of chronic prostatitis includes poor semen quality, decreased libido associated with pain upon prostatic contraction during ejaculation, and blood in the urine or semen sample.
Diagnosis: In acute cases of prostatitis, findings of an enlarged and/or painful prostate upon examination and evidence of bacteria in the urine of the dog, are highly indicative of this condition. A culture and sensitivity of urine removed from the bladder by cystocentesis is helpful for identifying the causative bacterial organism. Pain usually impedes the process of obtaining a prostatic fluid sample from the patient. Additionally, manipulation of the prostate should be avoided to prevent further spread of bacterial infection. In chronic cases, the prostate gland is typically painless or not as painful as in acute cases. This allows for collection of prostatic fluid for bacterial analysis since bacteria are not always found in the urine of dogs suffering from chronic prostatitis. Radiographic and ultrasonographic changes in the prostate are often apparent in dogs with chronic prostatitis. In cases where prostatic fluid culture does not identify an infectious organism, but diagnostic imaging is indicative of disease, biopsy of the prostate tissue will confirm a diagnosis of prostatitis.
Treatment and Prognosis: Aggressive treatment of acute prostatitis may prevent the infection from developing into chronic prostatitis. Results from urine culture and sensitivity screening will assist the clinician in selecting an antimicrobial drug with low potential for microorganism resistance and ability to maintain therapeutic concentrations in the urine and tissues. The anti-microbial agent is administered for at least 3-4 weeks to ensure complete elimination of the infection. Additionally, it is recommended that urine cultures and prostatic fluid cultures be analyzed 7-10 days after completion of drug therapy to ensure eradication of the infectious organisms. When treated aggressively and thoroughly, acute prostatitis is expected to have a good prognosis for recovery.
Chronic prostatitis is more challenging to treat and treatment difficulties are compounded by the fact that many anti-microbial drugs cannot efficiently cross the prostatic tissues and enter the prostatic fluid. Some anti-microbial agents are more soluble than others are and these are most effective for the treatment of chronic prostatitis. Such agents include: chloramphenicol, erythromycin, trimethoprim, ciprofloxacin, enrofloxacin, and carbenicillin. Therapy is typically continued for 4-6 weeks. Following completion of drug treatment, urine and prostatic fluid culture is performed at 4-7 days and 30 days following completion of treatment to ensure elimination of the infection. In many cases, follow-up culture indicates insufficient resolution of the infection by the first treatment regimen and a 3-month course of antibiotics with adjuvant therapy (hormone therapy or castration) to reduce concurrent prostatic hyperplasia is prescribed. Should this latter approach fail to eradicate infection, chronic low-dose antimicrobial therapy or prostatectomy are options to consider. Prognosis for chronic prostatitis is fair considering the limitations to therapy with antimicrobials against this disease and thus, the high incidence for relapse.
Cancer of the Prostate
Cause: Prostate cancer (prostatic adenocarcinoma [PAC]) is an uncommon disease in dogs but occurs with highest incidence in 8-10 year old intact and castrated males. In fact, risk of prostate cancer in early castrated males is equal to if not slightly higher than in intact males. This may be associated with the observation that castrated males usually do not manifest concurrent hyperplastic changes in the prostate as do intact males and thus maintain smaller tumor masses that may go undetected for longer periods of time allowing for a more invasive tumor phenotype to develop. Unlike human prostate cancer in which androgens appear to contribute significantly to neoplastic development, prostate cancer in dogs appears to be androgen independent. It is speculated, therefore, that early testosterone effects or nontesticular androgens of adrenal origin may play a role in the development and progression of prostate cancer in dogs.
Symptoms: Dogs with PAC develop symptoms consistent with enlargement of the prostate: difficulty urinating and/or defecating. Many dogs will also demonstrate anorexia and weight loss. Bone pain, an indication of tumor cell metastasis (spread) to the bone, may occur predominantly in the lower back and is a sign of late stage disease.
Diagnosis: In geriatric males, enlargement of the prostate in an intact male or a normal-sized prostate in a neutered male (since castration leads to complete atrophy of prostatic tissue) are suspicious for and highly suspected for PAC, respectively. Ultrasound-guided needle-core biopsy provides the best method for acquiring a definitive diagnosis of PAC and allows for evaluation of tumor grade, a clinical criteria that will assist in determining treatment options and prognosis.
Treatment and Prognosis: Tumors assessed as well-differentiated (closely resembling normal prostate cells) at the time of biopsy may indicate a better prognosis in terms of survival time. Unfortunately, however, PAC is often not diagnosed until the dog is in late stage of the disease when therapeutic options are limited and thus prognosis is considered poor. Surgery to remove the prostate is one possible option for therapeutic management of PAC and if the disease is detected in an early stage, this option may be curative. However, prostectomy is a difficult surgery and is associated with a chronic condition of urinary incontinence. Palliative treatment for PAC includes castration or hormonal therapy with Megestrol acetate or Finasteride to reduce concurrent prostatic hyperplasia and thus alleviate symptoms associated with prostate enlargement. For both intact and castrated males with PAC, external beam radiation therapy may induce temporary regression of the tumor and provide relief of symptoms. Administration of stool softeners may also provide some relief for constipation and because many PAC dogs will have secondary complications associated with bacterial infections, continuous antibiotic therapy may assist in controlling related symptoms. Despite therapeutic intervention with radiation or combination of radiation and chemotherapy, once diagnosis is made, survival time for dogs with PAC does not typically extend beyond 5 months.