Equis ISSN 2398-2977

Male: mounting/intromission difficulty

Contributor(s): Terry Blanchard, Rob Lofstedt, Graham Munroe, Elaine Watson, Madeleine L H Campbell

Introduction

  • Mounting and/or intromission failure may be a cause of infertility although ejaculation can still be stimulated to occur without either of these events.
  • Lack of libido Male: lack of libido can be a cause of mounting failure whereas erection failure Penis: erection failure will result in no intromission.
  • Cause: injury causing back, pelvic or hindlimb pain, psychological inhibition, genital pain or penile deformity can be implicated.
  • Signs: stallion either fails to mount mare/dummy (sometimes fails to mount at all; sometimes tries and fails to mount), or mounts but fails to gain intromission.
  • Diagnosis: clinical signs and associated tests.
  • Treatment: dependent upon cause.
  • Prognosis: dependent upon cause.

Pathogenesis

Etiology

  • Difficulty mounting:
    • Hindlimb or back orthopedic pain.
    • Neurological instability.
    • Mare too tall!
    • Psychological inhibition (association with pain, eg due to orthopedic problems or if previously kicked by a mare during breeding; association with being reprimanded).
  • Difficulty gaining intromission:
    • Penile deviation.
    • Injury to penis (stallions may gain intromission but they withdraw/fail to ejaculate due to pain Male: ejaculatory dysfunction). Penile abrasions are common. Mare's tail hairs can have a cheesewire effect on the penis. Such injuries may be minimized by wrapping the tails of mount mares, or using a dummy/phantom mare to prevent penile trauma Penis: trauma 05 - intromission  tail hairsPenis: trauma 04 - kick hematomaPenis: trauma 01 - lateral viewPenis: trauma 02 - caudal view.

Predisposing factors

General

  • Incompetent handling of the stallion/mare at the time of breeding can expose the stallion to injury.

Pathophysiology

  • Hind limb, pelvic or back pain Musculoskeletal: back pain can create a painful and potentially unstable situation for mounting. The horse is willing but not able and may collapse during an attempt to mount.
  • Psychological inhibition can sometimes cause the stallion to exhibit a lack of libido, or can sometimes cause the stallion to attempt mounting, but then dismount unpredictably/fail to ejaculate. 
  • Trauma to the penis causes scar tissue contracture and consequent deviation during erection. Intromission may be difficult or impossible (very rare in stallions but common in bulls).

Timecourse

  • Depending on cause.
  • Can be chronic and ongoing if degenerative joint disease (DJD) is involved.
  • If underlying problem is psychological can take a prolonged period to retrain stallion.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • McDonnell S M (2001) Oral imipramine and intravenous xylazine for pharmacologically-induced ex-copula ejaculations in stallions. Anim Reprod Sci 68 (3-4), 153-159 PubMed.
  • McDonnell S M (1992) Normal and abnormal sexual behavior. In: Veterinary Clinics of North America-Equine Practice: Stallion Management. Eds: Blanchard T L & Varner D D.  W B Saunders Co 8 (1), 71-90 PubMed.
  • McDonnell S M, Kenney R M, Meckley P C & Garcia M C (1985) Conditioned suppression of sexual behaviour in stallions and reversal with diazepam. Physiol Behav 34 (6), 951-956 PubMed.

Other sources of information

  • Martin B B & McDonnell S M (2003) Lameness in Breeding Stallions and Broodmares. In: Equine Lameness. Philadelphia, Saunders. pp 1077-1084.
  • Colahan P Tet al (1991) Equine Medicine and Surgery. 4th edn. American Veterinary Publications, Inc. ISBN: 0 939674 27 0. pp 884 (concise summary of main points).


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