**5. Prostate gland disorders**

### **5.1 Benign prostatic hyperplasia**

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 complex hyperplasia.

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 DHT in the prostate [1, 9].

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

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].

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**Figure 3.**

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

continuous use of the drug or cost of the drug [1].

There are other drugs that may be used as other options for the treatment of PH, such as progestogens, estrogens, analogues, and antagonists of GnRH, but they all have disadvantages when compared to finasteride, either concerning safety of the

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 prosta-

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

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

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

*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×.*

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

**5.2 Prostatic cysts**

tectomy [10, 13, 14].

**5.3 Squamous metaplasia**

affection [14].

cysts [10].

withdrawn [10].

There are other drugs that may be used as other options for the treatment of PH, such as progestogens, estrogens, analogues, and antagonists of GnRH, but they all have disadvantages when compared to finasteride, either concerning safety of the continuous use of the drug or cost of the drug [1].
