Abstract
Due to an unexplained low reproduction rate of captive Malayan sun bears (MSB, Helarctos malayanus), the European zoo population has decreased rapidly during the last 8 y from 73 to 49 individuals. There is strong evidence that pathologic alterations of the female genital tract cause infertility in a variety of wild species in captivity. Therefore, the aim of the present study was the investigation of reproductive health by ultrasound examinations.
In the course of the study, 17 female MSB (ages 2–25 years) from Europe and Thailand were anesthetized and examined by transrectal ultrasonography, as described before in ursids.1 The entire genital tract (vagina, cervix, uterine body, uterine horns and ovaries) was visualized in all bears.
In six out of 17 MSB (35.3%) cystic alterations of the uterine cervix were found in different sizes, which did not cause any clinical signs (Table 1). In four of these cases the animals were proven nulliparous. For the other two individuals no exact data was available, but were supposed to be nulliparous, too. The sonograms indicated fluid-filled structures within the cervical wall. In one MSB the physiologic structure of the uterine cervix could not be identified as a result of the cystic alterations. The uterus and the ovaries did not show any pathology. In other bears (62 individuals from four different species) cysts in the uterine cervix have never been observed. Type and origin of these cysts have not been characterized. However, microbiologic and histologic analyses are in progress. Surgical removal of large cysts in one animal failed. Ultrasound examination 2 years later revealed recidivation. In conclusion, we strongly suggest that cysts of the uterine cervix may contribute to infertility in MSB.
Table 1. Incidence of cystic alteration of the cervix uteri in Malayan sun bears of different ages
|
Age (y)
|
Number of individuals
|
Incidence of cystic alteration (%)
|
|
2–5
|
7
|
14.28
|
|
6–10
|
0
|
–
|
|
11–15
|
5
|
40
|
|
16–20
|
4
|
75
|
|
21–25
|
1
|
0
|
Literature Cited
1. Goeritz, F., T.B. Hildebrandt, K. Jewgenow, N. Wagner, R. Hermes, G. Strauß, and H.H.D. Meyer. 1997. Transrectal ultrasonographic examination of the female urogenital tract in nonpregnant and pregnant captive bears (Ursidae). J. Reprod. Fert. Suppl. 51: 303–312.