Transabdominal Ultrasound for Pregnancy Diagnosis in Reeves' Muntjac Deer

Summary

Transabdominal ultrasound is described as an effective, noninvasive means for assessing reproductive status in Reeves' muntjac deer. These methods can be used to achieve early pregnancy diagnosis and to evaluate fetal viability. Future applications of this technique include estimation of gestational age and effects of maternal disease on fetal development.

Abstract

Reeves' muntjac deer (Muntiacus reevesi) are a small cervid species native to southeast Asia, and are currently being investigated as a potential model of prion disease transmission and pathogenesis. Vertical transmission is an area of interest among researchers studying infectious diseases, including prion disease, and these investigations require efficient methods for evaluating the effects of maternal infection on reproductive performance. Ultrasonographic examination is a well-established tool for diagnosing pregnancy and assessing fetal health in many animal species^1-7, including several species of farmed cervids^8-19, however this technique has not been described in Reeves' muntjac deer. Here we describe the application of transabdominal ultrasound to detect pregnancy in muntjac does and to evaluate fetal growth and development throughout the gestational period. Using this procedure, pregnant animals were identified as early as 35 days following doe-buck pairing and this was an effective means to safely monitor the pregnancy at regular intervals. Future goals of this work will include establishing normal fetal measurement references for estimation of gestational age, determining sensitivity and specificity of the technique for diagnosing pregnancy at various stages of gestation, and identifying variations in fetal growth and development under different experimental conditions.

Introduction

Ultrasonographic examination is a well-described method of pregnancy diagnosis in cattle¹, sheep^2,3, goats⁴, horses⁵, companion animals^6,7, and other domestic animal species. This imaging modality has also been identified as a valuable tool for pregnancy detection and fetal age estimation in several species of captive cervids, including fallow deer^8-11, red deer^12-16, Hokkaido sika deer¹⁷, and reindeer^18,19. In many cases, ultrasonography has produced higher accuracy rates than other mechanisms of pregnancy detection, such as serum progesterone or pregnancy-associat....

Protocol

1. Procedural Preparation

All animal procedures described have been reviewed and approved by the Institutional Animal Care and Use Committee at Colorado State University, an Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC), Intl. accredited institution.

1. Prior to examination, immobilize animals using appropriate sedation or anesthesia protocols to provide relaxation and allow for appropriate positioning. One handler restrains the deer while a second person administers the sedation to the animal.
   Note: The authors have found the following combination to provide effective sedation in t....

Results

Using the protocol described here, pregnancy can be diagnosed and monitored in Reeve's muntjac deer with minimally invasive techniques. The earliest time point that pregnancy could be detected by the authors was approximately 35 days following observed mating behavior.

In the early stages of gestation, pregnancy was diagnosed by visualizing a fluid-filled uterus identified as an anechoic space in the caudal abdomen. Within the uterus, the developing embryo appeared as a hyperechoic, ovoid stru.......

Discussion

This protocol describes the application of transabdominal ultrasonography for pregnancy diagnosis in Reeves' muntjac deer. Consistent with other ultrasound studies, appropriate equipment and technical proficiency are imperative to a successful reproductive examination of the muntjac doe. Careful review of basic mammalian anatomy, the physical principles of diagnostic ultrasound, and the typical ultrasonographic appearance of the abdominal viscera will aid in the reduction of mistaken diagnoses. Furthermore, selection.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Butorphanol tartrate (Torbugesic) (0.45 mg/kg)	Fort Dodge Animal Health, Fort Dodge, Iowa	NADA 135-780
Azaperone tartrate (0.035 mg/kg)	ZooPharm
Medetomidine HCl (0.04 mg/kg)	ZooPharm
Ultrasound contact gel	Medline, Mundelein, Illinois	MDS092005
Atipamezole hydrochloride (Antisedan) (0.25 mg/kg)	Orion Corporation, Espoo, Finland	NADA 141-033
V-trough (optional)	N/A	N/A	Animal may be supported in dorsal recumbency on a standard examination table or other surface without the use of a V-trough
Electrical clippers or razor blades for hair removal	Oster, McMinnville, Tennessee	78005-140
Ultrasound system: Ibex Pro portable ultrasound	E.I. Medical Imaging, Loveland, CO	Ibex Pro
5-10 MHz transducer: CL3.8 5-2.5 MHz 60 mm curved linear array	E.I. Medical Imaging, Loveland, CO	290420
3 ml syringes	Covidien	1.18E+09
22 G needles	Covidien	8.88E+09