Equis ISSN 2398-2977

Endometrium: fibrosis

Synonym(s): Chronic degenerative endometrial disease (CDED), Endometriosis

Contributor(s): Annalisa Barrelet, John Dascanio, Jean Pierre Held, Graham Munroe, Madeleine L H Campbell

Introduction

  • A chronic degenerative uterine change diagnosed on histopathologic examination of uterine biopsy and characterized by stromal and periglandular fibrosis.
  • Cause: associated with repeated inflammatory insult.
  • Signs: the progression of this condition with age is an important contributing factor to the fall in fertility rate with increasing age of mares.
  • Fibrosis contributes to infertility by interfering with glandular and epithelial function.
  • The intrauterine release of nitric oxide in response to inflammatory signals, eg spermatozoa, may inhibit contraction of the myometrium.
  • This combination of interference with glandular, epithelial and contractile function constitutes a failure of normal uterine defense mechanisms.
  • Mares with endometrial fibrosis thus often exhibit intrauterine fluid upon ultrasound examination, and have a reduced ability to clear uterine inflammation.
  • Conception occurs but there is increased early embryonic or fetal death rate Abortion: early embryonic/fetal death.
  • Diagnosis: endometrial biopsy and histopathology.
  • Treatment: permanent conditions - various methods have been suggested to be helpful.
  • Prognosis: guarded to poor.

Pathogenesis

Etiology

  • Associated with repeated inflammatory insult.
  • Generally the result of inevitable "wear and tear" on the endometrium, ie repeated coverings/inseminations/uterine inflammation post-breeding or due to bacterial infection, etc (post-breeding endometritis), and is therefore more common in older mares.
  • May be seen in younger mares as a result of repeated bouts of antigenic challenge (uterine infection, mating, etc).

Predisposing factors

General

  • Repeated uterine infection, insemination, external genital and environmental debris, fetoplacental antigens, cycling (pregnancy, parturition and involution) and other antigenic challenges, including intrauterine treatments, appear to be the predisposing factors.
  • Often in older mares with a good breeding history the changes are less advanced than an age-matched mare which has had few or no foals (for example a multiparous brood mare compared with a competition mare presented for breeding as a maiden at the end of her competition career).

Pathophysiology

  • This is a progressive uterine condition associated with repeated antigenic stimulatory challenges interfering with glandular and epithelial function.
  • It is postulated that neutrophils (invading the endometrium in response to infectious stimulus) may cast out their DNA to form neturophil extracellular traps, which may upregulate fibrosis.
  • The intrauterine release of nitrous oxide in response to inflammatory signals, eg spermatozoa, may inhibit contraction of the myometrium.
  • Periglandular fibrosis interferes with endometrial glandular function which may also have a direct effect on the support of early conceptus (35-90 day old) leading to early embryonic/fetal death.
  • Other mares if they conceive may suffer prolonged gestation with fetal dysmaturity Reproduction: prematurity/dysmaturity.

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.
  • Reghini M et al (2016) Inflammatory response in chronic degenerative endometritis mares treated with platelet-rich plasma. Theriogenology 86 (2), 516-522 PubMed.
  • Rebordao M et al (2014) Physiopathological mechanisms involved in mare endometritis. Repro Dom Anim 49 (Suppl 4), 82-87 PubMed.
  • Allen W R (1993) Equine Endometritis; John P Hughes International workshop. Equine Vet J 25 (3), 184-193 PubMed.
  • Darenius K (1992) Early fetal death in the mare. Histologic, bacteriologic and cytologic findings in the endometrium. Acta Vet Scand 33 (2), 147-160 PubMed.
  • Ricketts S W & Alonso S (1991) The effect of age and parity on the development of equine chronic endometrial disease. Equine Vet J 23 (3), 189-192 PubMed.
  • Fraser G S et al (1988) Histopathologic effect of dimethyl sulfoxide on equine endometrium. Am J Vet Res 49 (10), 1774-1781 PubMed.
  • Kenney R M et al (1978) Cyclic and pathologic changes of the mare endometrium as detected by biopsy with a note on early embryonic death. JAVMA 72 (3), 241-262 PubMed.

Other sources of information

  • Held J P & Rohrbach S W (1991) Ability of Endometrial Biopsy Result, Parity and Age to Predict Subsequent Pregnancy in the Mare. In: Proc 37th Annual Conv. Am Assoc Equine Pract. pp 183-188.


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