*4.1.3 Differential diagnoses*

When the general condition is undisturbed, BPH can be mistaken for chronical prostatitis or beginning neoplasia in dogs.

*Diseases of the Canine Prostate Gland DOI: http://dx.doi.org/10.5772/intechopen.105835*

#### *4.1.4 Therapy*

Therapy is only necessary when clinical symptoms are visible. When the dog is asymptomatic, regular clinical and sonographical controls every 3–6 months are recommendable [42]. Vets can choose between different medicaments, providing the best choice for a subject [7].

The most effective method is the castration, involution starts within 6–12 weeks [7]. The clinical symptoms will disappear earlier and a decrease in size can mostly be palpated after 1–2 weeks [42]; the volume will decrease to 60% within one week [10], and by 50% after three weeks [39]. Bloody preputial discharge disappeared in 89% of cases within 4 weeks after castration [38]. Castration is the treatment of choice in case of hyperdistention, dyschezia, perineal hernia, or large retention cysts [42].

**Table 1** provides an overview of useful and recommendable medicaments against BPH

Medicaments with an antiandrogenic effect likewise and rapidly reduces the size of the gland. They competitively block the binding of testosterone to its receptors and decrease libido within 3 days. One example is cyproterone acetate, furthermore delmadinone acetate. Some preparations are not licensed for use in animals. These medicaments caused a reduction in canine prostate gland size by 28% within two weeks [82], and the clinical symptoms improved earlier. The duration of effectiveness is approximately 6 months when an average dose of 3 mg/kg is chosen. Side effects in male dogs are a latent diabetes mellitus and diseases of the mammary gland (tumors, hyperplasia, cysts, and galactorrhea).

For breeding dogs, medicaments not decreasing the libido are desirable, enabling examination of the semen quality while the dogs are still under treatment. for example osaterone acetate is a gestagene with anti-androgenic effect. It decreases the uptake of DHT in the prostate gland and decreases the activity of the 5α-reductase. Osaterone acetate furthermore suppresses the nuclear DHT- and androgen-receptor expression in the gland [86]. The size of the gland was significantly reduced to 62.6% within 7 days when a daily oral dose of 0.2–0.5 mg/kg was given [10]. A daily oral dose of 0.25 mg/kg for 7 days reduced the size to 64.3% within 14 days [84]; the testosterone concentration was significantly reduced for 3 months [10], then slowly increased, which is believed to point toward a low-grade anti-gonadotrophic effect [87]. The semen quality was low grade decreased during the therapy; the volume was decreased for 4 months. An increase in the percentage of morphological changings was observed 4 weeks after beginning of the therapy and during the following 1.5 months [10]. This medicament is recommendable for breeding dogs because of its rapid effect and the maintained libido. Within three months after beginning of the therapy, the sonographical appearance of the gland and the quality of the ejaculate are back to normal. Some side effects were observed: an increase in appetite for 1–3 weeks (3/15), lethargy (2/15), and low-grade loss of hair (1/15) [7].

This medicament is applicated orally; in case of vomiting, it is therefore not recommendable. In this case, injectable preparations are available for dogs.

In case of mild BPH, the 5α-Reductase-Inhibitor Finasteride is effective (for example Proscar® 5 mg Tabl. Merck, Vienna, A) [12]. Doses for dogs and duration of application are variable in the literature (Tab. 2) [42, 83]; however, the tablets should be given for 3–4 months. Since semen quality and libido are not changed by the medication, it is recommendable for breeding dogs [12, 83]. Finasteride is a teratogenic substance; nevertheless, fertility and resulting puppies are not concerned [85]. Side effects are not described.


*Overview of useful and recommendable medicaments against BPH.*

**Table 1.**

#### *Diseases of the Canine Prostate Gland DOI: http://dx.doi.org/10.5772/intechopen.105835*

For prolongation of an anti-androgenic therapy, long-lasting agonists of the gonadotropin-releasing hormone (GnRH) are suitable for dogs with BPH. Subcutaneous implants containing, for example, deslorelin (Suprelorin® 4.7 or 9.4 mg, Virbac, F) are licensed for male dogs and male ferrets. Many studies using different GnRH agonists and dosages are available, but difficult to compare [7]; however, deslorelin is the only licensed preparation. After resorption of a certain amount of GnRH, down-regulation of the GnRH receptors in the pituitary gland leads to a decrease in the secretion of the gonadotropins "follicle stimulating hormone" (FSH) and "luteinizing hormone" (LH), and consecutively to a decrease in the secretion of testicular testosterone by 90% and the spermatogenesis. The volume of the prostate gland decreases within 6 weeks by 50%, when a 4.7 mg implant is used [7, 51, 88], beginning after 37 days [51].

In dogs, the initial therapy leads to an increase in testosterone secretion; this flareup can be suppressed by oral application of an antiandrogen. This is important in case of an acute enlargement of the gland with acute symptoms [7].

GnRH antagonists can be used for therapy of canine BPH, unfortunately, the second generation of these drugs caused anaphylaxis in some cases. Meanwhile better agonists, which are potent, long-acting, and without side-effect, are available; however, they are only licensed for use in humans. Acyline is a preparation of the third generation and was used in one study at a dose of 330 mg/kg s.c. in dogs, leading to a reversible decrease in FSH, LH, and testosterone over 9 days. When a long-acting GnRH-agonist was used in dogs, Acyline successfully prevented a flare-up. In addition, the prostate volume was decreased by 38% after 30 days, echogenicity and heterogeneity were decreased, and the resistency-index (Doppler sonography) was normal again [89]. Monthly injections are required, rendering this medicament for short-term and exceptional use only. Further investigations with long-acting preparations would be of interest. Other medicaments like estrogens, antiestrogens, aldosterone-receptor antagonists, alpha1A-adrenerge-receptor antagonists, phosphodiesterase (PDE)-5 inhibitor, vitamin D receptor agonists, and intraprostatic injection of botulinus toxin type A (BT-A) were investigated; however, they are now obsolete or proved to be ineffective [7].

#### *4.1.5 Prognosis*

In dogs, the clinical symptoms can be effectively treated; however, the course of the disease is recurrent. Castration will finally resolve the problem. In stud dogs, special medicaments not decreasing the libido are available and fertility prognosis is good.

### *4.1.6 Prophylaxis*

Regular clinical and sonographical controls of the dogs are a good prophylaxis since only treatment or castration in time will prevent the disease. These controls are recommendable when the dog reached 40% of its estimated lifetime [18].

#### **4.2 Prostate gland cysts**

#### *4.2.1 Causes*

Cystic changes of the canine prostate gland (intraprostatic cysts) mostly develop in the aged gland, changed by BPH, because of accumulation of prostatic secretions in the dilated prostatic acini; furthermore because of obstruction, compression of intraprostatic channels, or accumulation of urine, when a connection between the cyst and the

urethra exists [90, 91]. Paraprostatic cysts are dilated residua of the Wolff channels; they can be situated in the cranio-lateral, ventral or caudal region of the prostate, and reach a remarkable size. In some cases, they become mineralized [90, 92]. Secondary infections and abscesses can be complications. In one study the prevalence of prostatic cysts was 14% (12/85) and 42% out of these were secondary infected [90].
