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Reproductive Tumors
and cysts 

Prevalence of tumors and cysts

Abegglen et al. (2022) published an overview of reproductive tumors in elephants:

"Asian elephants in particular are often diagnosed with benign uterine tumors called leiomyomas 
or fibroids (the term typically used to describe these lesions in humans). While malignant tumors overall are rare in elephants, when they do occur, the reproductive tract is disproportionately affected. Benign and malignant reproductive tract tumors are known to affect reproduction and pregnancy in other animals, and even tumors outside of the reproductive tract can have significant negative impacts on reproductive success."

 

In a literature study of the same authors the following reproductive anomalies were found in (aged) Asian elephants:

  • Uterine leiomyoma

  • Uterine adenocarcinoma

  • Anaplastic carcinoma (uterus)

  • Carcinoma in situ in endometrial polyp

  • Peripheral neuroectodermal tumor (uterus)

  • Angiosarcoma (uterus)

  • Anaplastic sarcoma (pelvic mass of presumed uterine origin)

  • Ovarian carcinoma

  • Ovarian cysts

  • Hyperplastic endometrial disease

  • Vestibular cysts

  • Vaginal leiomyoma

  • Hyperplastic, polyploidy or papillomatous mucosal lesions of vagina/vulva

  • Vagina polyps

  • Vulvar polyps

  • Uterine polyps

  • Uterus undifferentiated malignant neoplasm

The vast majority of reproductive pathologies in Asian elephants consists of uterine leiomyomas, followed by hyperplastic endometrial disease and cysts. 

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Reproductive tumors and cystic changed found in African elephants are:

  • Endometrial cysts

  • Ovarian carcinoma

  • Bilateral multilocular serous ovarian cystadenoma

  • Hyperplastic endometrial disease

  • Vestibular cysts

  • Vestibular polyps

  • Vagina polyps

Polyps and Hyperplastic endometrial disease are the most frequently encountered reproductive anomalies.

Symptoms and diagnosis

Most elephants suffering from the above mentioned disorders are aged and nulliparous. There are no hard data about the impact of these abnormalities on the reproduction. No doubt that large areas of  affected uterine surface may reduce implantation options for the embryo. The same applies to hyperplastic endometrial disease.

Large polyps in the distal reproductive tract can impede copulation by blocking the passage of the penis.

Symptoms are rarely observed. Occasionally blood loss can be observed in severe cases of leiomyomas.

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Diagnosis

The only way to diagnoses these reproductive disorders is by transrectal ultrasound examination. Location and severity of the abnormalities can be evaluated when they can be reached during this examination. 

Ultrasound image: leiomyoma

Figure 1: Transrectal examination in a 12 yr-old Asian elephant showing the early stage of an embryo in the left uterine horn and a large leiomyoma in the right uterine horn, clearly compressing the endometrium. The embryo developed normally and the elephant produced several calves after this diagnose was made.

Large leiomyoma in Asian elephant
Large leiomyoma in Asian elephant

Figure 2:  Leiomyoma (55 cm diameter) in an Asian elephant that produced 6 calves. (Courtecy: Planckendael Zoo)

Transrectal examination in an adult African elephant showing a cyst in the cervix uteri.

Figure 3: Transrectal examination in an adult African elephant showing a cyst in the cervix uteri.

Figure 4: Transrectal sonogram (4-2MHZ) of the uterus (UT) with a cystic (CY) degenerated endometrium. The rectal wall (RW) appears as a moderate echoic strip on the top of the sonogram (Fowler & Mikota 2006)

Figure 4: Transrectal sonogram (4-2MHZ) of the uterus (UT) with a cystic (CY) degenerated endometrium. The rectal wall (RW) appears as a moderate echoic strip on the top of the sonogram (Fowler & Mikota 2006)

Treatment of severe cases of leiomyomas

Female elephants suffering of chronic pathological conditions in the reproductive tract (leiomyomas) may benefit from a permanent shut-down of the estrous cycle by the administration of gonadotrophin releasing hormones (GnRH) vaccins. The following  schedule should be used:
A minimum of 450 μg of a GnRH vaccine (i.e. 3ml of Improvac©, Zoetis Animal Health)* deep intramuscularly once per month for 3 months. Thereafter booster vaccinations are given every 6 months (please note that some individuals may not respond and thus, require higher doses of up to 1000 μg protein conjugate or more frequent injection, in this case, please contact the vet advisors). Other available commercial products/brand names are Improvest©, Equity© and Bopriva©, depending on country.

References

  • Abegglen, L.M.; Harrison, T.M.; Moresco, A.; Fowles, J.S.; Troan, B.V.; Kiso,W.K.; Schmitt,D.;  Boddy, A.M.; Schiffman, J.D. 2022. Of Elephants and Other Mammals: A Comparative Review of Reproductive Tumors and Potential Impact on Conservation. Animals 2022, 12, 2005. https://doi.org/10.3390/ani121520052022

  • Reproductive Tumors and Potential Impact on Conservation

  • Boedeker et al. 2012. Effects of a gonadotropin-releasing hormone vaccine on ovarian cyclicity and uterine morphology of an Asian elephant (Elephas maximus). Journal of Zoo and Wildlife Medicine 43(3): 603–614, 2012.

  • Landolfi JA, Gaffney PM, McManamon R, et al. Reproductive tract neoplasia in adult female Asian elephants (Elephas maximus). Veterinary Pathology. 2021;58(6):1131-1141. https://doi:10.1177/03009858211031843

  • Lueders et al. 2019. Use of gonadotrophin releasing hormone (GnRH) vaccines for behavioural and reproductive control in managed Asian elephant Elephas maximus and African elephant Loxodonta africana populations. Int. Zoo Yb. (2019) 53: 138–150.

  • Thitaram et al. 2018. Monitoring and controlling ovarian activity in elephants. Theriogenology 109, 42-47.

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