Managing Canine BPH in Breeding Dogs: A Fertility-Centric Clinical Approach

Benign prostatic hyperplasia (BPH) is the most common prostatic disorder in dogs, affecting approximately 50% of intact males by 4 years of age and more than 90% by 8 years¹. Despite its high prevalence, the condition is frequently subclinical, making early detection challenging. In breeding dogs, however, even subclinical disease holds significant importance because of its potential impact on reproductive performance and semen quality. 

Hormonal Basis and Disease Progression 

The enlargement of the prostate in BPH is driven by a combination of hypertrophy and hyperplasia. Hypertrophy, primarily influenced by estrogen, results in an increase in cell size, while hyperplasia, characterized by increased cell number, plays a more dominant role in overall prostate enlargement. The underlying mechanism involves the conversion of testosterone to dihydrotestosterone (DHT) through 5α-reductase activity, which drives cellular proliferation within the prostate. Estrogen further enhances this process by increasing androgen receptor expression and stimulating stromal proliferation, thereby amplifying androgenic effects on prostatic tissue^1,2,3,4,5. 

Clinical Manifestations and Reproductive Implications 

Although many dogs remain asymptomatic, BPH can present with clinical signs such as hematospermia, hematuria, dysuria, constipation, and tenesmus^1,4. In advanced stages, complications such as prostatitis, cyst formation, and perineal hernia may occur. In breeding dogs, the condition is strongly associated with reduced fertility. Studies indicate that 32.8% of infertile dogs are affected by BPH. The disease contributes to increased sperm DNA fragmentation and morphological abnormalities, largely due to oxidative stress within the prostatic environment¹. 

The hyperplastic prostate produces elevated levels of reactive oxygen species, leading to oxidative imbalance and reduced antioxidant defenses. Since prostatic fluid forms a major component of seminal plasma, this altered biochemical environment directly affects spermatozoa, making them more susceptible to oxidative damage and reducing overall semen quality^1,6. 

Therapeutic Considerations in Breeding Dogs 

While surgical or chemical castration is effective for BPH management, these approaches are unsuitable for breeding dogs where fertility preservation is essential^1,7. Therefore, medical therapy becomes the primary approach, requiring careful selection to balance efficacy with reproductive safety. 

Finasteride: A Fertility-Preserving Option 

Finasteride, a competitive 5α-reductase inhibitor, reduces DHT levels without binding to androgen receptors, which may explain its relatively minimal impact on reproductive function. Clinical studies have demonstrated symptom resolution within 30 days when administered at doses ranging from 0.1 to 0.5 mg/kg SID¹. However, prostate size reduction is gradual, typically becoming significant after 60 days of treatment^1,8. 

Higher doses, such as 1 mg/kg SID, result in more rapid and substantial reductions in prostate volume, reaching up to 47–54% after 12 weeks¹. Imaging studies also show improvements in prostatic structure, including resolution of small cysts. Despite these benefits, histological changes remain minimal, suggesting that finasteride primarily influences functional rather than structural aspects of the prostate¹. 

From a reproductive standpoint, finasteride does not significantly affect sperm motility, morphology, or viability, although a temporary reduction in semen volume has been observed . Interestingly, improvements in DNA integrity and sperm binding capacity have been reported in cryopreserved semen, indicating a potential positive effect on sperm quality under certain conditions¹. 

Osaterone Acetate: Rapid Symptom Control 

Osaterone acetate, a steroidal antiandrogen, provides a faster therapeutic response compared to finasteride. Clinical improvement is often observed shortly after a seven-day treatment regimen, with remission rates ranging from 82.6% to 100%^1,9,10. Prostate volume reduction can occur as early as 14 days after treatment initiation, reaching significant levels by 60 days ^1,10. 

However, the effects are not permanent, and relapse may occur within six months, necessitating retreatment. While osaterone acetate effectively improves ultrasonographic features and reduces cysts, its impact on reproductive parameters is variable. Temporary alterations in sperm morphology and motility have been reported, although these changes generally resolve over time¹. 

GnRH Antagonists and Fertility Concerns 

GnRH antagonists such as acyline and linzagolix demonstrate strong efficacy in reducing prostate size and alleviating clinical signs. However, their effects on fertility are significant. Studies have reported marked reductions in sperm concentration and motility, with cases of aspermia observed during treatment¹. These findings highlight the potential risks associated with their use in breeding dogs. 

Conclusion 

Managing BPH in breeding dogs requires a carefully balanced approach that addresses clinical symptoms while preserving reproductive function. Finasteride remains a reliable option due to its favorable safety profile and minimal impact on semen quality, whereas osaterone acetate offers rapid symptom relief but may require closer reproductive monitoring. Ultimately, treatment decisions should be individualized, with regular assessment of both prostate health and semen parameters to achieve optimal outcomes. 

References:  

1. Posastiuc FP, Constantin NT, Domain G, Soom AV, Diaconescu AI, Codreanu MD. A systematic review of medical treatments for benign prostatic hyperplasia in dogs: Evaluating strategies for reproductive function preservation. Veterinary sciences. 2025 Jan 19;12(1):70. https://doi.org/10.3390/vetsci12010070 

2. Miller MA, Zachary JF. Mechanisms and morphology of cellular injury, adaptation, and death. Pathologic basis of veterinary disease. 2017 Feb 17:2. https://pmc.ncbi.nlm.nih.gov/articles/PMC7171462/ 

3. Hata J, Harigane Y, Matsuoka K, Akaihata H, Yaginuma K, Meguro S, Hoshi S, Sato Y, Ogawa S, Uemura M, Kojima Y. Mechanism of androgen-independent stromal proliferation in benign prostatic hyperplasia. International Journal of Molecular Sciences. 2023 Jul 19;24(14):11634. https://www.mdpi.com/1422-0067/24/14/11634 

4. Cristian, A.M.; Codreanu, I.; Codreanu, M. Benign Prostatic Hyperplasia—Prevalence and Clinical Sonographic Features in Dogs. Sci. Works. Ser. C. Vet. Med. 2021, 67, 43–47. https://veterinarymedicinejournal.usamv.ro/pdf/2021/issue_2/Art6.pdf 

5. Chen B, Cao D, Chen Z, Huang Y, Lin T, Ai J, Liu L, Wei Q. Estrogen regulates the proliferation and inflammatory expression of primary stromal cell in benign prostatic hyperplasia. Translational Andrology and Urology. 2020 Apr;9(2):322. https://pmc.ncbi.nlm.nih.gov/articles/PMC7214965/pdf/nihpp-rs4169007v1.pdf 

6. Domoslawska A, Zdunczyk S, Bielecka A, Kankofer M. The effect of benign prostatic hyperplasia on total antioxidant capacity and protein peroxidation in canine prostatic fluid and spermatozoa. Polish journal of veterinary sciences. 2023;26(4). https://agro.icm.edu.pl/agro/element/bwmeta1.element.agro-423d3abd-6a18-484c-a574-f45746ae2b9d/c/14___Domoslawska.pdf 

7. Cazzuli G, Damián JP, Molina E, Pessina P. Post‐castration prostatic involution: A morphometric and endocrine study of healthy canines and those with benign prostatic hyperplasia. Reproduction in Domestic Animals. 2022 Feb;57(2):157-64. https://doi.org/10.1111/rda.14036 

8. Angrimani DS, Francischini MC, Brito MM, Vannucchi CI. Prostatic hyperplasia: Vascularization, hemodynamic and hormonal analysis of dogs treated with finasteride or orchiectomy. PloS one. 2020 Jun 25;15(6):e0234714. https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0234714&type=printable 

9. Niżański W, Ochota M, Fontaine C, Pasikowska J. Comparison of clinical effectiveness of deslorelin acetate and osaterone acetate in dogs with benign prostatic hyperplasia. Animals. 2020 Oct 21;10(10):1936. https://www.mdpi.com/2076-2615/10/10/1936 
10. Socha P, Zduńczyk S, Tobolski D, Janowski T. The effects of osaterone acetate on clinical signs and prostate volume in dogs with benign prostatic hyperplasia. Polish journal of veterinary sciences. 2018;21(4):797-802. https://bibliotekanauki.pl/articles/2087646.pdf