Serial Ultrasonographic Evaluation of the Non-Gravid and Gravid Uterus of the Giant Anteater (Myrmecophaga tridactyla) for Determination of Pregnancy, Estimation of Parturition Date, and Breeding Management
American Association of Zoo Veterinarians Conference 2009
Anne Elise Napier1, DVM; Sally A. Nofs2, DVM; Nancy C. Boedeker3, DVM
1Ultrasound Solutions, Nashville, TN, USA; 2Nashville Zoo at Grassmere, Nashville, TN, USA; 3National Zoological Park, Smithsonian Institution, Washington, DC, USA


Successful breeding programs are dependent on reliable pregnancy detection for care of the gestating female and the neonate. Since giant anteaters (Myrmecophaga tridactyla) do not significantly alter estrus behavior during pregnancy and their body type is not conducive to detection by abdominal palpation, alternative methods of confirmation must be employed. Indirect means of evaluation such as vaginal cytology and fecal estrogen/progesterone assay have been established in the giant anteater.1,2 Additionally, transabdominal ultrasound has been utilized as a direct means of establishing pregnancy.1 The goal of this study was to provide a complete description of ultrasonographic findings in both non-gravid and gravid females in order to establish objective criteria for identification and staging of pregnancy in the giant anteater. Ultrasonographic exams were performed in non-sedated, stationed, healthy, reproductively active female giant anteaters to provide ultrasonographic images for various stages of the non-gravid uterus and for the gravid uterus beginning at five weeks post copulation. Exams were performed at regular intervals to monitor growth of the fetus and establish ultrasonographic criteria for estimation of fetal age. Pregnancy was first identified at 10 weeks post copulation, established by identification of amniotic fluid, fetal structure, motion, and heartbeat. By 14 weeks all fetal structures were identified. Serial structural measurements (heart girth diameter, length of the long bones, and cranium) were evaluated in gestating animals to prepare a growth curve from identification until parturition.

Literature Cited

1.  Schauerte N. Untersuchungen zur Zyklus-und Graviditätsdiagnostik beim Großen Ameisenbären (Myrmecophaga tridactyla). Dr. Med Vet Dissertation, Justus Liebig University, Giessen, Germany. Accessed 2005.

2.  Patzl M, Schwarzenberger F, Osmann C, Bamberg E, Bartmann W. Monitoring ovarian cycle and pregnancy in the giant anteater (Myrmecophaga tridactyla) by faecal progestogen and oestrogen analysis. Anim Reprod Sci. 1998;53:209–219.


Speaker Information
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Anne Elise Napier, DVM
Ultrasound Solutions
Nashville, TN, USA

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