**5.2 Prostatic cysts**

*Veterinary Anatomy and Physiology*

an understudied area.

complex hyperplasia.

DHT in the prostate [1, 9].

may or may not contain cysts [1, 10].

**5. Prostate gland disorders**

**5.1 Benign prostatic hyperplasia**

The prostate depends on the testosterone that is produced in the testicles and converted into dihydrotestosterone (DHT) by the enzyme 5α-reductase. It is known that without this hormonal stimulus, the prostate will decrease its secretory function and volume. Castrated dogs lack testosterone, and consequently DHT will lead the prostate to a state of atrophy [7]. Thus, the endocrine control of the prostate gland, mainly by testis, is well characterized. In male dogs, the testosterone is the most important circulating androgen, and CYP19 (aromatase) can be metabolized into an estradiol-17β. The estrogen can affect the prostate gland growth and differentiation. The role of androgen in prostatic development and pathological process is

Benign prostatic hyperplasia (BPH) is the most common prostatic pathology in dogs. There is a discordance among pathologists regarding the term "BPH." Since hyperplasia is a term applied for a benign growth, using "benign" prostatic "hyperplasia" seems redundant. However, the term BPH is widely accepted in the international literature. Prostatic hyperplasia (PH) or BPH begins as a process of glandular hyperplasia that can occur around the age of 2–3 years. In intact dogs over 9 years, it affects more than 95% of the population [10]. This condition is part of the normal aging process and may include both hyperplastic and hypertrophic processes [1]. Histologically, the PH can be divided into two entities: glandular and

PH is closely related to hormone stimulation in the prostate, indirectly by estrogen and directly by DHT, the former of which causes an increase in the receptors for DHT, and DHT is directly responsible for prostatic growth when binding to epithelial cell receptors of the prostatic cells. In addition, older dogs can present high levels of testosterone production by the testicle that will be converted into

Many dogs affected by PH do not show clinical signs until the prostate is large enough to disrupt fecal flow through rectum compression. The most common clinical signs for PH are hematuria, constipation, blood-stained urethral discharge, and hemospermia [10]. The presumptive diagnosis of PH is usually performed by associating the patient's clinical signs with the ultrasonography findings; however, for a definitive diagnosis, the histopathological examination of a prostatic sample is required [1]. The use of ultrasonography is indicated to aid in the evaluation of the extent of the lesion in which the prostate may present as a honeycomb due to the appearance of multiple cysts or as a symmetrical hyperplasia of the gland, which

Neutering is still the most effective and recommended method of treatment of PH in most dogs with a 50–70% decrease in prostate volume at 3 weeks after the surgical procedure; however, the complete decrease of the prostate can take a month [10]. Surgery is contraindicated in cases where the risk of the procedure is too high or if the animal is used for reproduction. In these cases the drug treatment is indicated. The most commonly used drug for the treatment of PH is finasteride, an inhibitor of 5α-reductase, the enzyme responsible for the conversion of testosterone to DHT. This drug has been widely used in humans for more than 10 years. The use of finasteride decreases prostate volume by 43% after 16 weeks. Although the volume of the ejaculate decreases, the use of finasteride does not alter the seminal quality of

the dogs or the libido and may be an option for breeding animals [11].

**90**

The appearance of prostatic cysts most often is related to PH. Cysts can be classified as intraprostatic or paraprostatic. Intraprostatic or retention cysts arise due to the clogging of the prostatic gland ducts, causing the prostatic fluid to accumulate [9]. At the beginning of this condition, the cysts are very small and not detectable by ultrasonography or rectal palpation, but with the evolution of the condition, many small cysts begin to communicate forming a large cavity that can be detected macroscopically [10, 12].

Paraprostatic cysts are closely associated with remnants of the uterus masculinus, tend to be larger than intraprostatic ones, and can be palpated rectally or even transabdominally [1]. The clinical signs caused by prostatic cysts are very similar to the signs of conditions that cause an increase in prostatic volume, that is, they are reflex of the prostate pressing other structures that are located in the pelvis [12].

The diagnosis of prostatic cysts is performed by ultrasonography, but in cases where the cysts are very small, they may not be detected. The traditional treatment for prostatic cysts is surgical, by any of these techniques: surgical debridement, omentalization, marsupialization, placement of surgical drains, or partial prostatectomy [10, 13, 14].

However, due to the risks of a surgical intervention, new techniques of ultrasound guided drainage are presented as viable options for the treatment of this affection [14].

### **5.3 Squamous metaplasia**

Continuous stimulation of prostatic epithelial cells by estrogen may lead to squamous metaplasia. This estrogenic stimulus may be exogenous or endogenous [15]. The source of endogenous estrogen in animals with squamous metaplasia is the Sertoli cell neoplasia. As in PH, there is a trend toward the formation of prostatic cysts [10].

Squamous metaplasia (**Figure 3**) does not directly cause any clinical signs. This prostatic alteration is reversible if the endogenous or exogenous estrogen source is withdrawn [10].

#### **Figure 3.**

*Canine squamous metaplasia of the prostate gland. It is possible to observe a squamous differentiation of the prostatic epithelium, forming filaments of keratins in the lumen. An inflammatory infiltrate, composed by mononuclear cells, is also observed. Hematoxylin and eosin (H&E) staining, 20×.*

#### **5.4 Prostatitis**

Prostatitis is a prostate infection that affects mainly older dogs. The origin of the infection can be both ascending by the urinary tract and by hematogenous spread, the second case being rare. Other prostatic conditions such as PH or cysts may compromise the natural defense mechanisms of the prostate and may lead to the development of prostatitis [1, 10].

The most relevant microorganisms linked to prostatitis are *Escherichia coli*, *Staphylococcus*, *Streptococcus* spp., *Mycoplasma* spp., *Proteus*, *Klebsiella* spp., *Pseudomonas aeruginosa*, *Enterobacter*, *Pasteurella* spp., and *Brucella canis*. In rare cases, prostatitis can be caused by fungi [10, 12].

Prostatitis can be divided into two types: acute, in which the infection is more recent and the inflammatory process is more exacerbated and chronic, in which the clinical signs are milder.

The treatment of prostatitis should take into account some key factors for it to be successful. It is of extreme importance for the choice of the drug to evaluate the result of the culture of the prostatic fluid or semen; in addition, one should take into account the pharmacodynamics of the chosen active principle, since the prostate is a tissue of difficult penetration of the antibiotics due to the difference in pH between the prostate fluid and blood [1, 9].

Antibiotic treatment in the case of bacterial prostatitis should last for at least 4 weeks, and a new culture of prostatic fluid and urine should be performed before the end of treatment so that it can be decided between completion and continuation. A new culture test is also recommended 30 days after the end of treatment so that its success is confirmed [1].

Trimethoprim sulfa, chloramphenicol, and enrofloxacin are antibiotics that have good penetration into the prostatic tissue and are therefore good candidates for the treatment of bacterial prostatitis [16].

Castration is indicated as adjuvant therapy to reduce prostate volume and prevent relapse; however, castration should not be performed during acute infection to avoid complications [16].

#### *5.4.1 Acute prostatitis*

In acute prostatitis, the infection is more recent, the inflammation is more intense, and the clinical signs presented are anorexia, fever, apathy, vomit, hypogastric region pain, and preputial discharge. In addition, the complete blood count is a characteristic of an acute infectious process, with neutrophilia and left-sided deviation [1].

Diagnosis should be made based on the animal's history and physical examination associated with exams such as transrectal prostate palpation, ultrasonography, complete blood count, urinalysis, and culture of prostate fluid or semen in cases where collection is possible [1].

In prostate palpation, it is common for the animal to present painful sensitivity due to the inflammatory process present there. In ultrasonography, the prostate will most often be enlarged, with its echogenicity increased, and may or may not have associated cysts or abscesses. Urine and semen will most often have neutrophils and bacteria present [1].

#### *5.4.2 Chronic prostatitis*

Unlike acute prostatitis, few chronic or no clinical signs are exhibited by the animal. The most common are recurrent urinary tract infections and bloody

**93**

**Figure 4.**

*(H&E) staining, 10×.*

*Anatomy, Histology, and Physiology of the Canine Prostate Gland*

urethral discharge. In addition, in rectal palpation, the prostate often has a normal volume, and the animal has no painful sensitivity. Because of this, the diagnosis in this case is more difficult and should be based on the clinical findings associated with ultrasonography and culture of the prostatic fluid or semen

The difference of "acute" and "chronic" is usually a clinical classification, since both entities present a very divergent clinical signs, prognosis, and treatment. In a pathological "view," inflammation is usually classified into focal or multifocal and according to the inflammatory infiltrate (cell type involved) and the presence or

In humans, the chronic inflammatory infiltrate associated with the epithelial atrophy is described as a proliferative inflammatory atrophy (PIA) and is consid-

Prostatic abscesses can be consequences of prostatic cysts that become contaminated or of prostatitis. In the case of prostatitis, tissue inflammation can induce obstruction of the prostatic ducts, causing contaminated contents to accumulate

The diagnosis is achieved through the association of history, clinical signs, and complementary tests. The signs of prostatic abscesses are related to the increased prostatic volume, the most common being tenesmus and dysuria. In addition, the animal may or may not feel pain during rectal palpation of the prostate. Ultrasonography and culture of the prostatic fluid are important tests for the

The treatment is based on draining the contents of the abscess. The most traditional ones are surgical intervention such as debridement and omentalization, marsupialization, subtotal prostatectomy, or placement of multiple penrose drains. However, due to the risks associated with these procedures, new approaches are

in association with the technique chosen for drainage of the abscess [14].

An alternative to the traditional surgical approach is the percutaneous drainage of the abscesses guided by ultrasonography, which in addition to being a cheaper technique than traditional surgery proved to be safe and effective. In addition, antibiotic therapy based on the result of prostatic fluid culture should be instituted

*Canine prostatic atrophic epithelium. There is atrophy of the glandular epithelium, disposed in two or more layers. There is an intense inflammatory mononuclear infiltrate and hemorrhage. Hematoxylin and eosin* 

ered as a preneoplastic lesion [17]. In dogs, PIA is also found (**Figure 4**).

*DOI: http://dx.doi.org/10.5772/intechopen.81410*

absence of intraluminal infiltration.

**5.5 Prostatic abscesses**

resulting in an abscess [18].

emerging [14].

diagnosis of prostatic abscesses [1, 14].

[1, 9].

### *Anatomy, Histology, and Physiology of the Canine Prostate Gland DOI: http://dx.doi.org/10.5772/intechopen.81410*

urethral discharge. In addition, in rectal palpation, the prostate often has a normal volume, and the animal has no painful sensitivity. Because of this, the diagnosis in this case is more difficult and should be based on the clinical findings associated with ultrasonography and culture of the prostatic fluid or semen [1, 9].

The difference of "acute" and "chronic" is usually a clinical classification, since both entities present a very divergent clinical signs, prognosis, and treatment. In a pathological "view," inflammation is usually classified into focal or multifocal and according to the inflammatory infiltrate (cell type involved) and the presence or absence of intraluminal infiltration.

In humans, the chronic inflammatory infiltrate associated with the epithelial atrophy is described as a proliferative inflammatory atrophy (PIA) and is considered as a preneoplastic lesion [17]. In dogs, PIA is also found (**Figure 4**).

## **5.5 Prostatic abscesses**

*Veterinary Anatomy and Physiology*

development of prostatitis [1, 10].

clinical signs are milder.

that its success is confirmed [1].

avoid complications [16].

where collection is possible [1].

*5.4.1 Acute prostatitis*

deviation [1].

bacteria present [1].

*5.4.2 Chronic prostatitis*

treatment of bacterial prostatitis [16].

cases, prostatitis can be caused by fungi [10, 12].

pH between the prostate fluid and blood [1, 9].

Prostatitis is a prostate infection that affects mainly older dogs. The origin of the infection can be both ascending by the urinary tract and by hematogenous spread, the second case being rare. Other prostatic conditions such as PH or cysts may compromise the natural defense mechanisms of the prostate and may lead to the

The most relevant microorganisms linked to prostatitis are *Escherichia coli*, *Staphylococcus*, *Streptococcus* spp., *Mycoplasma* spp., *Proteus*, *Klebsiella* spp., *Pseudomonas aeruginosa*, *Enterobacter*, *Pasteurella* spp., and *Brucella canis*. In rare

Prostatitis can be divided into two types: acute, in which the infection is more recent and the inflammatory process is more exacerbated and chronic, in which the

The treatment of prostatitis should take into account some key factors for it to be successful. It is of extreme importance for the choice of the drug to evaluate the result of the culture of the prostatic fluid or semen; in addition, one should take into account the pharmacodynamics of the chosen active principle, since the prostate is a tissue of difficult penetration of the antibiotics due to the difference in

Antibiotic treatment in the case of bacterial prostatitis should last for at least 4 weeks, and a new culture of prostatic fluid and urine should be performed before the end of treatment so that it can be decided between completion and continuation. A new culture test is also recommended 30 days after the end of treatment so

Trimethoprim sulfa, chloramphenicol, and enrofloxacin are antibiotics that have good penetration into the prostatic tissue and are therefore good candidates for the

Castration is indicated as adjuvant therapy to reduce prostate volume and prevent relapse; however, castration should not be performed during acute infection to

In acute prostatitis, the infection is more recent, the inflammation is more intense, and the clinical signs presented are anorexia, fever, apathy, vomit, hypogastric region pain, and preputial discharge. In addition, the complete blood count is a characteristic of an acute infectious process, with neutrophilia and left-sided

Diagnosis should be made based on the animal's history and physical examination associated with exams such as transrectal prostate palpation, ultrasonography, complete blood count, urinalysis, and culture of prostate fluid or semen in cases

In prostate palpation, it is common for the animal to present painful sensitivity due to the inflammatory process present there. In ultrasonography, the prostate will most often be enlarged, with its echogenicity increased, and may or may not have associated cysts or abscesses. Urine and semen will most often have neutrophils and

Unlike acute prostatitis, few chronic or no clinical signs are exhibited by the animal. The most common are recurrent urinary tract infections and bloody

**5.4 Prostatitis**

**92**

Prostatic abscesses can be consequences of prostatic cysts that become contaminated or of prostatitis. In the case of prostatitis, tissue inflammation can induce obstruction of the prostatic ducts, causing contaminated contents to accumulate resulting in an abscess [18].

The diagnosis is achieved through the association of history, clinical signs, and complementary tests. The signs of prostatic abscesses are related to the increased prostatic volume, the most common being tenesmus and dysuria. In addition, the animal may or may not feel pain during rectal palpation of the prostate. Ultrasonography and culture of the prostatic fluid are important tests for the diagnosis of prostatic abscesses [1, 14].

The treatment is based on draining the contents of the abscess. The most traditional ones are surgical intervention such as debridement and omentalization, marsupialization, subtotal prostatectomy, or placement of multiple penrose drains. However, due to the risks associated with these procedures, new approaches are emerging [14].

An alternative to the traditional surgical approach is the percutaneous drainage of the abscesses guided by ultrasonography, which in addition to being a cheaper technique than traditional surgery proved to be safe and effective. In addition, antibiotic therapy based on the result of prostatic fluid culture should be instituted in association with the technique chosen for drainage of the abscess [14].

#### **Figure 4.**

*Canine prostatic atrophic epithelium. There is atrophy of the glandular epithelium, disposed in two or more layers. There is an intense inflammatory mononuclear infiltrate and hemorrhage. Hematoxylin and eosin (H&E) staining, 10×.*
