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 25-28 September, 2018 | Singapore
irregularity, and the urethroprostatic reflux may be normal or greater than normal. On ultrasound, the prostate
may appear diffusely hyperechoic with parenchymal cavities (which means that intraprenchymal cysts have developed). The canine prostate is best evaluated in the sagittal and transverse planes using 5.0 or preferably
7.5 MHz scanners. An enema should be administered prior to scanning to eliminate colonic contents which may mimic peripheral prostatic disease. Conditions such as cysts or abscesses are visualized easily. Other less distinct but echogenically complex areas may indicate neoplasia or areas of infection within the gland. Although technically a definitive diagnosis of BPH is only possible by biopsy, such an invasive approach is not necessary to institute a therapy if clinical signs are present, and from a practical standpoint ultrasound assessment of prostatic size and presence of cysts is often the only thing that
is necessary to identify the problem and start dealing with it. No alteration of haematological or biochemical parameters are commonly observed in dogs with BPH7.
Canine BPH can be difficult to differentiate from other most common prostatic disorders (prostatitis, prostatic cysts, carcinoma and adenocarcinoma) because of
the similarity of clinical findings. In men with prostatic carcinoma the use of serum markers such as acid phosphatase (AcP) and prostate specific antigen (PSA) has facilitated determination of the extent of disease, evaluation of therapeutic response and detection of relapse after therapy. Information about these markers is still controversial in the dog. Serum and seminal prostatic AcP activities do not differ significantly between normal dogs and those with prostatic diseases, or among dogs with different prostatic disorders8; PSA is not detected
in canine serum or seminal plasma. The major secretory product of the canine prostate is canine prostate-specific arginine esterase (CPSE) which constitutes more than 90% of seminal proteins in this species. CPSE is a
known marker of dog prostatic secretion9,10. Screening for CPSE is of potential value in the aging intact
male dogs. Its measurement is a useful and accurate method and should be considered as an alternative
or complementary tool to conventional methods for
the diagnosis of BPH in middle-aged dogs. CPSE is under testosterone control and, therefore, may serve as functional marker of the androgenic state and response to antiandrogenic therapy, either by receptor antagonists or 5-alpha-reductase inhibitors. Although further research is necessary to define the exact role of CPSE, it seems to be a promising diagnostic tool in nonneoplastic canine prostatic disorders.
Treatment for canine BPH
Surgical or pharmacological castration (using GnRH agonists) or the administration of estrogens, steroidal
or non-steroidal antiandrogens can be used11. Although occasionally reported as an effective treatment for BPH, estrogens carry the potential risk of serious bone marrow
side effects (anemia, leukopenia, thrombocytopenia, pancitopenia) as well as the risk of growth of the fibromuscular stroma of the prostate which may cause metaplasia of the prostatic glandular epithelium and secretory stasis resulting in prostatic enlargement and predisposition to cyst formation, bacterial infection and abscessation12. Therefore, we do not currently advice using estrogens to treat canine prostatic hyperplasia. Estrogen receptor blocker may be used to treat BPH
as they compete with androgen receptors thereby decreasing prostatic size and weight (although the altered ratio estrogen:testosterone is not modified
which means that number and size of prostatic cysts do not change). Recently, tamoxifen (an estrogen receptor blocker with a mixed antagonist-agonist action) has been reported to be efficacious and devoid of side effects in male dogs with BPH (except for a decrease in libido and semen quality)13; following 28 days of treatment at the daily dose of 2.5 mg/day, tamoxifen caused a decrease in testicular and prostatic size as well as testosterone and libido13. Tamoxifen does not seem to have serious side effects and may be an interesting adjunct treatment for canine BPH, although there is no information
on its long-term effect and safety and more studies are probably necessary before it can be prescribed routinely13.
Castration – The most effective treatment to induce regression of prostatic hyperplasia is castration, after which prostatic size may decrease as much as 50% in 3 weeks and 70% over 9 weeks14. Orchiectomy has long been considered the treatment of choice for those dogs whose reproductive function is not important to the owner. As post-castration involution begins within days of surgery, prostatic size should be assessed 3 weeks post- operatively to make sure the involution rate is normal thus ruling out a more serious prostatic disease such as neoplasia or abscessation. Surgical castrations should not be performed in the presence of prostatic infections due to the risk of scirrhous cord development, in which case it would be better to administer a specific antibiotic treatment based on semen culture and sensitivity. With regard to orchiectomy, one important thing to consider
is that incidence of prostatic carcinoma in adult/elderly dogs could be higher in castrated rather than in intact dogs; reasons for this are not entirely known yet, but
it is speculated that once prostatic atrophy starts, neoplastic cells already present will increase their growth rate perhaps due to lack of suppressing action of testosterone15,16,17. For this reason we do not currently advice our clients to castrate their adult to elderly dogs unless it is strictly necessary (i.e. if there is a testicular tumor).
Steroidal antiandrogens - Steroidal antiandrogens compete with androgen receptors and perhaps also with DHT receptors at the cellular level in target organs. Compounds such as megestrol acetate,
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43RD WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND 9TH FASAVA CONGRESS










































































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