Equis ISSN 2398-2977

Male: lack of libido

Synonym(s): Impotence

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

Introduction

  • Libido refers to sexual drive or the psychological energy directed toward copulation.
  • Lack of libido is a problem of sexual desire which results in a lack of arousal and therefore a loss or decrease in ability to achieve intromission.
  • It afflicts sexually immature stallions or mature stallions that may have been overused or injured/abused or in which copulation has become associated with pain.
  • Lack of libido can be influenced by genetics, hormones, environment, previous injury and experience.
  • It can have economic significance for busy studs.

Pathogenesis

Predisposing factors

General
  • Young stallions (2 years old) new to the task often take their time in the early days. Most overcome any shyness within a couple of weeks with patient handling.
  • The effect of season is important: early in the season, mounts per service is increased, reaction time is increased and libido is generally decreased in stallions of all ages.
  • The increasing numbers of stallions combining competition work with stud duties may lead to confusion when the stallion has been inhibited from exhibiting stallion behavior in the presence of other horses. Stallions which have been reprimanded for rearing/showing interest in mares during their competition career may be loathe to exhibit normal libido when they go to stud.
  • The management regime must separate the events in a way to prepare the horse for the different situations.
  • Overuse of a stallion may result from booking too many mares.
  • Personal preferences can develop where the stallion prefers certain mares of certain colors.
  • Some horses work better with their preferred stallion groom.
  • Breed effect is important: Standardbreds   Standardbred  and Thoroughbreds   Thoroughbred  have poor libido in comparison with Warmbloods   Dutch warmblood  , eg a Standardbred/Thoroughbred may breed 2-3 mares per day or 30-45 mares per season while some Warmbloods can breed up to 10 mares per day and up to 200 per season by natural cover. Normal variation between individuals in any particular breed as well. In Ireland, many Thoroughbreds breed many more than 45 mares per season.
  • Stallions with hindlimb or back problems which cause them pain during covering/semen collection quickly learn to associate breeding with pain and this is reflected in a loss of libido.

Specific

  • Hormone imbalance - low circulating testosterone   Endocrine: testosterone assay  or luteinizing hormone; likely to occur at the onset of the breeding season.

Pathophysiology

Inexperience of the stallion
  • May include competition horses that have been made to control their 'stallion' tendencies in company.
  • Young novice stallions.

Mismanagement

  • Lack of knowledge with respect to stallion behavior and modification and control of it by handlers.
  • Overbooking too many mares thus presenting too great a number to mate on a daily basis: some stallions sometimes simply lose interest during the height of the breeding season, particularly if they are not being exercised in a sufficient and stimulating way otherwise. 
  • Pain from injury to penis or scrotum   Penis: trauma  . May arise from previous use of 'aids' to discourage erection or masturbation, eg stallion ring, brush tied on ventral abdomen.
  • Pain due to old injury, eg handle or back problem which is exacerbated by mounting.
  • When breeding is by artificial insemination, some stallions which exhibit normal libido during natural mating may be uninterested when confronted with a dummy mare; some stallions dislike particular models/temperature/pressure of artificial vagina.

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.
  • Malmgren L, Andresen O & Dalin A M (2001) Effect of GnRH immunisation on hormonal levels, sexual behaviour, semen quality and testicular morphology in mature stallions. Equine Vet J 33 (1), 75-83 PubMed.
  • McDonnell S M (2000) Reproductive behavior of stallions and mares: comparison of free-running and domestic in-hand breeding. Anim Repro Sci 60-61 (1), 211-219 PubMed.
  • McDonnell S M & Odian M J (1994) Imipramine and xylazine-induced ex-copula ejaculation in stallions. Theriogenology 41 (5), 1005-1010 PubMed. 
  • Hurtgen J P (1992) Evaluation of the stallion for breeding soundness. Vet Clin North Am Equine Pract (1), 149-165 PubMed.
  • McDonnell S M & Love C C (1990) Manual stimulation collection of semen from stallions: training time, sexual behaviour and semen. Theriogenology 33, 1201-1210 SciDirect.
  • Berntson W E et al (1979) Influence of exogenous testosterone on sperm production, seminal quality and libido of stallions. J Reprod Fertil Suppl 27, 19-23 PubMed.

Other sources of information

  • Samper J C, Pycock J F & McKinnon A O (2007) Stallion Reproductive Behaviour. In: Current Therapy in Equine Reproduction. Saunders Elsevier, USA. pp 174-185.
  • Forney B D & McDonnell S M (1999) How to Collect Semen from Stallions while they are Standing on the Ground. In: Proc 45th AAEP Congress. Albuquerque. pp 142-155.
  • McKinnon A O & Voss J L (1993) Equine Reproduction. Eds: Lea & Febiger. pp 825-7. ISBN 0 8121 1427 2.


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