Endometrosis

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Endometrosis is a chronic degenerative syndrome of the lining of the uterus (the endometrium) in mares. [1] There are no explicit symptoms and the cause is also unknown, but the severity of endometrosis increases in parallel with the age and number of pregnancies of the mare. [2] Endometrosis is confirmed by histological examination of an endometrial biopsy, which shows degeneration of blood vessels in the endometrium, and fibrosis of the tissue, along with the development of endometrial cysts. [2] The most common classification for endometrosis in mares was published by KENNY u. DOIG (1986) and modified by SCHOON et al. (1992). [3] The different degrees of endometriosis are divided into stage I, IIA, IIB and III. [3] These changes cause subfertility; [1] in pregnant mares, the changes in the endometrium can cause the placenta to fail, leading to miscarriage of the foal. [2] Foals which are delivered at full term may be underdeveloped (dysmature). [4] No effective treatment is known. [4] Since the causes of endometrosis are unsettled there is not known much about how to prevent it. [5]

Contents

The etymology of endometrosis is from the Greek endos (inside), metra (womb) and -osis (disease). [1] This term was adopted in 1992; [6] prior to that, endometrosis was variously known as chronic degenerative endometritis, endometrial fibrosis, or chronic endometrial disease. [6] [7]

Symptoms and Occurrence

There are no explicit symptoms, but suspicious are mares with low infertility or embryonic deaths. [8] Endometrosis occurs most commonly in older mares or mares that have foaled at least twice, but in general all ages can be affected. [2] However, there seems to be no relation between the occurrence or degree of endometrosis and the number of previous foalings. [9] Also natural seasonal and cyclical changes in the endometrium seem to not affect the disease. [9]

Causes and Pathogenesis

The causes of endometrosis are still unsettled. [3] Most of the time endometrosis co-occurs with endometritis which may activate the periglandular fibrotic stroma cells, but it hasn't been proven. [3] Endometrial periglandular fibrosis are the most common abnormalities that occur in mares with endometrosis. [9] When the periglandular endometrial stromal cells look and function atypical it is a first sign for endometrosis. [10] Mares who suffer from endometrosis seem to be unable to produce enough histotrophe, which leads to an embryonic loss of the foal. [9]

Classification

The degree of endometrial fibrosis is classified by different systems based on histopathological examination. [3] The most common is the classification by KENNY u. DOIG (1986) which was modified by SCHOON et al. (1992). [10] The classification is divided into three or rather four stages (I,IIA,IIB,III) which consider degenerative endometrial changes based on degree of fibrosis, glandular alteration and glandular nests with or without periglandular fibrosis and glandular atrophy. [3] The staging is influenced by different factors like taking a biopsy during or not during breeding season or histopathological examination after treatment against the endometritis which co-occurs most of the time. [3]

Stages

The following table shows the different degrees of endometrosis which is classified by KENNY u. DOIG (1986) and modified by SCHOON et al. (1992). [10]

CategoryDegreeHistopathological viewExpected foaling rate
Ivery low
  • endometrium is unaltered
  • isolated foci of fibrosis and inflammation
80-90%
IIAlow
  • diffuse inflammation
  • low periglandular fibrosis and small fibrotic nests (<2 foci)
  • partial atrophy in late breeding season
  • lymphatic lacunae
50-80%
IIBmoderate
  • category IIA
  • focal inflammation
  • widespread periglandular fibrosis and fibrotic nests (2-5 foci)
  • widespread lymphatic changes
10-50%
IIIhigh
  • category IIB
  • high focal inflammation
  • widespread periglandular fibrosis and fibrotic nests (>4 foci)
  • atrophy during breeding season
  • severe lymphatic lacunae
<10%

Diagnosis

Endometrosis is most often diagnosed in barren mares. [10] For the diagnostic procedure the endometrium of mares are biopsied to examine the changes in the endometrium under microscope. [9] Therefore a small piece of tissue is removed from the endometrium of the mare, which is subjected to conventional histopathology. [9] The only contraindication for endometrial biopsy is pregnancy. [10]

Treatment

As the changes in the endometrium are seen as irreversible there is no effective treatment available. [10] But to prevent infection antibiotics are administered in the uterus [10]  

Prevention and Prognosis

Since the causes of endometrosis are unsettled there is not known much about how to prevent it. [5] But a good breeding management seems important to lower the chance of mares becoming endometrosis. [5] Endometrosis is more common in mares that have been used irregularly for breeding. [5] Also strict veterinary supervision increases the foaling rates of mares significantly. [5] As endometrosis is a chronic disease the mare will remain unfertile and the foal may be underdeveloped. [4]

Related Research Articles

<span class="mw-page-title-main">Endometrium</span> Inner mucous membrane of the mammalian uterus

The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The functional layer thickens and then is shed during menstruation in humans and some other mammals, including apes, Old World monkeys, some species of bat, the elephant shrew and the Cairo spiny mouse. In most other mammals, the endometrium is reabsorbed in the estrous cycle. During pregnancy, the glands and blood vessels in the endometrium further increase in size and number. Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus. The speculated presence of an endometrial microbiota has been argued against.

<span class="mw-page-title-main">Horse breeding</span> Human-directed process of selective horse breeding

Horse breeding is reproduction in horses, and particularly the human-directed process of selective breeding of animals, particularly purebred horses of a given breed. Planned matings can be used to produce specifically desired characteristics in domesticated horses. Furthermore, modern breeding management and technologies can increase the rate of conception, a healthy pregnancy, and successful foaling.

<span class="mw-page-title-main">Endometriosis</span> Disease of the female reproductive system

Endometriosis is a disease of the female reproductive system. It occurs in humans and a limited number of menstruating mammals. In endometriosis, cells like those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Lesions can be found on ovaries, fallopian tubes, tissue around the uterus and ovaries (peritoneum), intestines, bladder, and diaphragm; and may also occur in other parts of the body. Symptoms include pelvic pain, heavy and painful periods, pain with bowel movements, painful urination, pain during sexual intercourse and infertility. Nearly half of those affected have chronic pelvic pain, while 70% feel pain during menstruation. Up to half of affected individuals are infertile. About 25% of individuals have no symptoms and 85% of those seen with infertility in a tertiary center have no pain. Endometriosis can have both social and psychological effects.

<span class="mw-page-title-main">Endometrial cancer</span> Uterine cancer that is located in tissues lining the uterus

Endometrial cancer is a cancer that arises from the endometrium. It is the result of the abnormal growth of cells that have the ability to invade or spread to other parts of the body. The first sign is most often vaginal bleeding not associated with a menstrual period. Other symptoms include pain with urination, pain during sexual intercourse, or pelvic pain. Endometrial cancer occurs most commonly after menopause.

<span class="mw-page-title-main">Pyometra</span> Medical condition

Pyometra or pyometritis is a uterine infection. Though it is most commonly known as a disease of the unaltered female dog, it is also a notable human disease. It is also seen in female cattle, horses, goats, sheep, swine, cats, rabbits, hamsters, ferrets, rats and guinea pigs. Pyometra is an important disease to be aware of for any dog or cat owner because of the sudden nature of the disease and the deadly consequences if left untreated. It has been compared to acute appendicitis in humans, because both are essentially empyemas within an abdominal organ.

<span class="mw-page-title-main">Adenomyosis</span> Extension of endometrial tissue into the myometrium

Adenomyosis is a medical condition characterized by the growth of cells that proliferate on the inside of the uterus (endometrium) atypically located among the cells of the uterine wall (myometrium), as a result, thickening of the uterus occurs. As well as being misplaced in patients with this condition, endometrial tissue is completely functional. The tissue thickens, sheds and bleeds during every menstrual cycle.

<span class="mw-page-title-main">Vaginal bleeding</span> Medical condition

Vaginal bleeding is any expulsion of blood from the vagina. This bleeding may originate from the uterus, vaginal wall, or cervix. Generally, it is either part of a normal menstrual cycle or is caused by hormonal or other problems of the reproductive system, such as abnormal uterine bleeding.

<span class="mw-page-title-main">Equine infectious anemia</span> Species of virus

Equine infectious anemia or equine infectious anaemia (EIA), also known by horsemen as swamp fever, is a horse disease caused by a retrovirus and transmitted by bloodsucking insects. The virus (EIAV) is endemic in the Americas, parts of Europe, the Middle and Far East, Russia, and South Africa. The virus is a lentivirus, like human immunodeficiency virus (HIV). Like HIV, EIA can be transmitted through blood, milk, and body secretions. Transmission is primarily through biting flies, such as the horse-fly and deer-fly. The virus survives up to 4 hours in the vector. Contaminated surgical equipment and recycled needles and syringes, and bits can transmit the disease. Mares can transmit the disease to their foals via the placenta. The risk of transmitting the disease is greatest when an infected horse is ill, as the blood levels of the virus are then highest.

<span class="mw-page-title-main">Endometritis</span> Medical condition

Endometritis is inflammation of the inner lining of the uterus (endometrium). Symptoms may include fever, lower abdominal pain, and abnormal vaginal bleeding or discharge. It is the most common cause of infection after childbirth. It is also part of spectrum of diseases that make up pelvic inflammatory disease.

Intermenstrual bleeding (IMB) is vaginal bleeding at irregular intervals between expected menstrual periods. It may be associated with bleeding with sexual intercourse.

<span class="mw-page-title-main">Relaxin</span> Protein hormone

Relaxin is a protein hormone of about 6000 Da, first described in 1926 by Frederick Hisaw.

Taylorella equigenitalis is a Gram-negative, non-motile, microaerophilic bacterium of the genus Taylorella, and the causative agent of contagious equine metritis (CEM) in horses. Phylogeny of T. equigenitalis includes being part of the Alcaligenaceae family.

<span class="mw-page-title-main">Endometrial hyperplasia</span> Medical condition

Endometrial hyperplasia is a condition of excessive proliferation of the cells of the endometrium, or inner lining of the uterus.

Contagious equine metritis (CEM) is a type of metritis in horses that is caused by a sexually transmitted infection. It is thus an equine venereal disease of the genital tract of horses, brought on by the Taylorella equigenitalis bacteria and spread through sexual contact. The disease was first reported in 1977, and has since been reported worldwide.

<span class="mw-page-title-main">Deslorelin</span> Chemical compound

Deslorelin, sold under the brand names Ovuplant, SucroMate, and Suprelorin among others, is an injectable gonadotropin releasing hormone superagonist which is used in veterinary medicine for various indications.

<span class="mw-page-title-main">Endometrioma</span> Medical condition

Endometrioma is the presence of tissue similar to, but distinct from, the endometrium in and sometimes on the ovary. It is the most common form of endometriosis. Endometrioma is found in 17–44% patients with endometriosis.

<span class="mw-page-title-main">Endosalpingiosis</span> Medical condition

Endosalpingiosis is a condition in which fallopian tube-like epithelium is found outside the fallopian tube. It is unknown what causes this condition. It is generally accepted that the condition develops from transformation of coelomic tissue. It is often an incidental finding and is not usually associated with any pathology.

<span class="mw-page-title-main">Metritis</span> Inflammation of the wall of the uterus

Metritis is inflammation of the wall of the uterus, whereas endometritis is inflammation of the functional lining of the uterus, called the endometrium. The term pelvic inflammatory disease (PID) is often used for metritis.

Microglandular hyperplasia (MGH) of the cervix is an epithelial benign abnormality (lesion) associated with gland proliferation. It can terminate in mature squamous metaplasia, and it is suspected reserve cells are involved in this process, perhaps in the form of reserve cell hyperplasia with glandular differentiation.

References

  1. 1 2 3 Hanada, M; Maeda, Y; Oikawa, MA (2014). "Histopathological characteristics of endometrosis in thoroughbred mares in Japan: results from 50 necropsy cases". Journal of Equine Science. 25 (2): 45–52. doi:10.1294/jes.25.45. PMC   4090358 . PMID   25013358.
  2. 1 2 3 4 Sprayberry, Kim A (2009). "Chapter 20: Fetal monitoring in broodmares". In Samper, JC (ed.). Equine breeding management and artificial insemination (2nd ed.). St. Louis, Missouri: Saunders/Elsevier. pp. 241–248. ISBN   9781416052340.
  3. 1 2 3 4 5 6 7 Sieme, Prof Dr Harald; Lehmann, Julia (2010-11-23). "Morphologisch-funktionelle Untersuchungen zur prognostischen Bewertung der equinen Endometrose".{{cite journal}}: Cite journal requires |journal= (help)
  4. 1 2 3 Munroe, G; Campbell, M; Munroe, Z; Hanks, M (2011). "Chapter 2.1: Female reproductive tract. Chronic degenerative endometrosis". In Munroe, GA; Weese, J. Scott (eds.). Equine clinical medicine, surgery, and reproduction. London: Manson Publishing/The Veterinary Press. p. 318. ISBN   9781840766080.
  5. 1 2 3 4 5 Doig, P. A.; McKnight, J. D.; Miller, R. B. (March 1981). "The Use of Endometrial Biopsy in the Infertile Mare". The Canadian Veterinary Journal. 22 (3): 72–76. ISSN   0008-5286. PMC   1789874 . PMID   7026016.
  6. 1 2 Flores, JM; Rodríguez, A; Sánchez, J; Gómez-Cuétara, C; Ramiro, F (April 1995). "Endometrosis in Mares: Incidence of Histopathological Alterations". Reproduction in Domestic Animals. 30 (2): 61–65. doi:10.1111/j.1439-0531.1995.tb00606.x.
  7. ↑ "What is Endometriosis? It's causes, diagnosis, treatment". Archived from the original on 2021-09-09. Retrieved 2021-09-09.
  8. ↑ Aresu, Luca; Benali, Silvia; Giannuzzi, Diana; Mantovani, Roberto; Castagnaro, Massimo; Falomo, Maria Elena (June 2012). "The role of inflammation and matrix metalloproteinases in equine endometriosis". Journal of Veterinary Science. 13 (2): 171–177. doi:10.4142/jvs.2012.13.2.171. ISSN   1229-845X. PMC   3386342 . PMID   22705739.
  9. 1 2 3 4 5 6 Lehmann, J.; Ellenberger, C.; Hoffmann, C.; Bazer, F. W.; Klug, J.; Allen, W. R.; Sieme, H.; Schoon, H. -A. (2011-10-15). "Morpho-functional studies regarding the fertility prognosis of mares suffering from equine endometrosis". Theriogenology. 76 (7): 1326–1336. doi:10.1016/j.theriogenology.2011.06.001. ISSN   0093-691X. PMID   21855986.
  10. 1 2 3 4 5 6 7 Buczkowska, J.; Kozdrowski, R.; Nowak, M.; Raś, A.; Mrowiec, J. (2014-09-01). "Endometrosis – significance for horse reproduction, pathogenesis, diagnosis, and proposed therapeutic methods". Polish Journal of Veterinary Sciences. 17 (3): 547–554. doi: 10.2478/pjvs-2014-0083 . ISSN   2300-2557. PMID   25286671. S2CID   8793946.
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