ISSN 2398-2977      

Female: anestrus during ovulatory season

pequis

Introduction

  • A period of true anestrus with complete absence of luteal function is occasionally seen during the physiologic breeding season.
  • Cause: obscure; nutritional factors may be involved. Rarely (3-4% of foaling mares), may be a true lactational anestrus. Sometimes associated with having foaled very early in the breeding season (when days are still short) - mares enter a period of anestrus following foaling and then start to cycle normally once day length increases.
  • Signs: ovarian inactivity and loss of uterine tone.
  • Diagnosis: serial plasma progesterone assays.
  • Treatment: wait for return to cyclicity or GnRH by minipump or implant.
  • Prognosis: reasonable unless nearing the end of the ovulatory season, in which case return to cyclicity may be delayed until the next year.

Pathogenesis

Etiology

  • Difficult to elucidate where only one horse affected.
  • Nutritional factors may be responsible where a number of horses in a group affected, especially mares in poor body condition or older mares.
  • Individual mares may be in true lactational anestrus.
  • Common cause of anestrus in mares with foal at foot (lactational anestrus).
  • In individual mares may be associated with foaling early in season.

Diagnosis

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Meyers P J et al (1997) Use of GnRH analog, deslorelin acetate, in a slow-release implant to accelerate ovulation in oestrous mares. Vet Rec 140 (10), 249-252 PubMed.
  • Koskinen E, Huhtinen M & Katila T (1996) Serum progesterone levels in mares in winter and during transitional periods. Acta Vet Scand 37 (94), 409-414 PubMed.
  • Meinert C et al (1993) Advancing the time of ovulation in the mare with short-term implant releasing the GnRH analog deslorelin. Equine Vet J 25 (1), 65-68 PubMed.
  • Alexander S L & Irvine C H (1991) Control of onset of breeding season in the mare and its artificial regulation by progesterone treatment. J Reprod Fertil Suppl 44, 307-318 PubMed.
  • Davis S D & Sharp D C (1991) Intra-follicular and peripheral steroid characteristics during vernal transition in the pony mare. J Reprod Fertil Suppl 44, 333-340 PubMed.
  • Nequin L G, King S S, Matt K S & Jurak R C (1989) The influence of photoperiod on gonadotropin-releasing hormone stimulated lutenizing hormone release in the anestrus mare. Equine Vet J 22 (5), 56-358 PubMed.
  • Kelly C M, Hoyer P B & Wise M E (1988) In-vitro and in-vivo responsiveness of the corpus luteum of the mare to gonadotropin stimulation. J Reprod Fertil 84 (10), 593-600 PubMed.
  • Lofstedt R M (1988) Control of the estrous cycle in the mare. Vet Clin North Am Equine Pract 4 (2), 177-196 PubMed.
  • Hyland J H et al (1987) Infusion of gonadotropin-releasing hormone (GnRH) induces ovulation and fertile estrus in mares during seasonal anestrus. J Reprod Fertil Suppl 35, 211-220 PubMed.
  • Allen W E et al (1987) Extraspecific donkey-in-horse pregnancy as a model of early fetal death. J Repro Fert Suppl 35, 197-209 PubMed.

Other sources of information

  • Thompson D L (2001) Anestrus. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Wiley Blackwell, UK. pp 1696-1701.

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code