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Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions: First Case Reports.
Abstract: Pharmacological aids can be useful alternatives to enhance penile erection and/or improve ejaculatory function, thereby prolonging the reproductive life of stallions with ejaculatory disorders. This study aimed to evaluate the effects of sildenafil citrate in the treatment of erectile dysfunction and on semen quality in two aged stallions, a Quarter Horse (18 years) and a Mangalarga Marchador (25 years), presented to the Veterinary Hospital of FMVZ-UNESP, Botucatu, SP, Brazil. The treatment consisted of oral administration of sildenafil citrate at 0.2 mg/kg. Thirty minutes after administration, the Quarter Horse stallion achieved full erection and ejaculated in all collection attempts (100%; 3/3), with semen parameters within normal ranges for the species. The Mangalarga Marchador showed a partial response to treatment, with successful ejaculation in only one of three attempts (33.3%) and exhibited oligozoospermia, possibly associated with previously identified age-related testicular degeneration concurrent with the erectile dysfunction. To the best of the authors' knowledge, this is the first report on the use of sildenafil citrate for managing erectile dysfunction in stallions, demonstrating its therapeutic potential. However, the results suggest individual variability in response to treatment, indicating the need for additional controlled studies to establish more precise dose-response protocols.
© 2026 The Author(s). Reproduction in Domestic Animals published by Wiley‐VCH GmbH.
Publication Date: 2026-09-08 PubMed ID: 42706915PubMed Central: PMC13551068DOI: 10.1111/rda.70318Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Case Reports
Summary
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Overview
- This study examined the use of sildenafil citrate (a medication commonly known as Viagra) to treat erectile dysfunction in two aged stallions and assessed its effects on their semen quality.
- The research demonstrated that sildenafil citrate could help improve erectile function and ejaculation in stallions, though responses varied between individuals.
Background and Purpose
- Stallions with ejaculatory disorders often face challenges in reproductive performance, particularly when aged.
- Pharmacological interventions can potentially enhance penile erection and ejaculatory function, thereby prolonging stallions’ reproductive lifespan.
- This study aimed to investigate the use of sildenafil citrate as a treatment for erectile dysfunction in two older stallions and evaluate its impact on semen quality.
Study Subjects
- Two aged stallions:
- A 18-year-old Quarter Horse
- A 25-year-old Mangalarga Marchador
- Both stallions were presented to the Veterinary Hospital at FMVZ-UNESP in Botucatu, Brazil, with diagnosed erectile dysfunction.
Methodology
- The treatment involved oral administration of sildenafil citrate at a dosage of 0.2 mg per kg of body weight.
- Semen collection attempts were made 30 minutes after administration to assess erectile and ejaculatory response.
- Semen samples were evaluated for quality parameters relative to normal species standards.
Results
- Quarter Horse Stallion
- Achieved full erection within 30 minutes of administration.
- Successfully ejaculated during all three collection attempts (100% success).
- Semen parameters were within normal ranges, indicating effective treatment with no negative impact on semen quality.
- Mangalarga Marchador Stallion
- Exhibited only partial response to sildenafil treatment.
- Successfully ejaculated only once in three collection attempts (33.3% success).
- Showed oligozoospermia (low sperm count), likely related to pre-existing age-related testicular degeneration alongside erectile dysfunction.
Conclusions and Implications
- This is the first reported case of sildenafil citrate use for erectile dysfunction treatment in stallions.
- The medication demonstrated therapeutic potential to improve erectile and ejaculatory function in aged stallions.
- Individual variability in response was notable, indicating that not all stallions may benefit equally from treatment.
- The findings suggest the need for additional, controlled studies to refine dosage, evaluate long-term efficacy, and establish standardized treatment protocols.
- Overall, sildenafil citrate could become a valuable tool in veterinary reproductive medicine to enhance breeding performance in aged or affected stallions.
Cite This Article
APA
Cavalero TMS, Papa FO, Monteiro GA, Papa PM, Hartwig FP, Freitas-Dell'Aqua CP, Alvarenga MA, Freitas MSE, Sancler-Silva YFR.
(2026).
Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions: First Case Reports.
Reprod Domest Anim, 61(9), e70318.
https://doi.org/10.1111/rda.70318 Publication
Researcher Affiliations
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Animal Science, Federal University of Viçosa, UFV, Viçosa, Minas Gerais, Brazil.
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
- Department of Animal Science, Federal University of Viçosa, UFV, Viçosa, Minas Gerais, Brazil.
MeSH Terms
- Animals
- Male
- Sildenafil Citrate / therapeutic use
- Horses
- Erectile Dysfunction / drug therapy
- Erectile Dysfunction / veterinary
- Horse Diseases / drug therapy
- Semen Analysis / veterinary
- Ejaculation / drug effects
Conflict of Interest Statement
The authors declare no conflicts of interest.
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