Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions

Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions: First

Case Reports
Reprod Domest Anim. 2026 Sep;61(9):e70318. doi: 10.1111/rda.70318.
Authors
Thaís Mendes Sanches Cavalero 1 , Frederico Ozanam Papa 1 , Gabriel Augusto Monteiro 1 , Patrícia de Mello Papa 1 , Felipe Pires Hartwig 1 , Camila de Paula Freitas-Dell’Aqua 1 , Marco Antônio Alvarenga 1 , Marcela Souza E Freitas 2 , Yame Fabres Robaina Sancler-Silva 1 2
Affiliations

1 Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, UNESP, Botucatu, São Paulo, Brazil.
2 Department of Animal Science, Federal University of Viçosa, UFV, Viçosa, Minas Gerais, Brazil.

PMID: 42706915
DOI: 10.1111/rda.70318

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.

Keywords: chemical ejaculation; penile erection; semen; stallion sexual behaviour.

© 2026 The Author(s). Reproduction in Domestic Animals published by Wiley‐VCH GmbH.

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