Pregnancy Diagnosis in Sheep and Goats (Ewes and Does)
Pregnancy diagnosis (cyesiognosis) in sheep and goats (ewes and does) done by external palpation, abdominal ballottement, recto-abdominal palpation (Hulet’s technique), radiography, ultrasonography, hormonal assays, etc.
Following techniques used for PD in sheep and goats:
- External palpation
- Abdominal ballottement
- Recto-abdominal palpation technique (Hulet’s technique)
- Radiography
- Ultrasonography
- Hormonal assays
None of these clinical methods give reliable diagnosis before 3 months of gestation, while technological methods have little application in developing countries, especially under field conditions.
Bimanual Palpation Technique
- Bimanual palpation technique method involves digital palpation per rectum combined with abdominal manipulation
- The urinary bladder is emptied before examination
- Sitting at the level of pelvic region on the right side of the animal, the examiner’s pre lubricated, gloved index finger of the left hand is introduced in to the rectum.
- Fecal pellets are removed and a distended urinary bladder is evacuated by gentle recto-abdominal pressure.
- The right palm is held vertically, with the finger tips touching the ventral floor of the posterior abdomen; it is then lifted upwards to move abdominal organs forward
- Then, using regulated forward, upward, and backward movements, the reproductive tract within the pelvic cavity could be held in palm of the right hand
- Examination is performed per rectum using the left index finger assisted by the fingers of the right hand.
Recto-Abdominal Palpation
- Recto-abdominal palpation method was described by Hulet and hence the name, Hulet’s Technique.
- This technique involves use of a glass or steel rod (50 cms long and 1.5 cms diameter) inserted in rectum.
- A soap enema is given 5 minutes before examination to evacuate the rectum.
- The ewe or doe is turned on her back.
- The probe is lubricated with paraffin oil and carefully inserted approximately 30 cms inside the rectum.
- Left palm is placed on the abdominal wall and the rod is moved to and fro in a horizontal plane with the right hand.
- If the rod is palpable as it moves slowly with no obstruction to its passage across the abdomen from side to side, the ewe is considered non-pregnant. If a palpable mass is detected with the free hand through the abdominal wall on one or both sides, the ewe is pregnant and the number of fetuses assessed according to the size and position of masses, wherever possible.
- The rectum and uterus should be carefully examined for injury or damage following examination.
Ultrasonography Method
Ultrasonographic determination of pregnancy has been well documented in sheep and has been reported to some extent in goats and has been discussed under the following headings.
- Preparation and restraint
- Speed and accuracy of the procedure
- Transrectal ultrasonography
- Trans-abdominal ultrasonography
The choice of the transducer is typically between the linear array and sector. Transducers of 3 to 5 MHz frequencies are most commonly employed.
Quite reliable from 30 days of gestation to term with transabdominal use of sector scanners. Identification of single vs multiple fetuses are most accurate from 45 to 90 days of gestation.
Transrectal Ultrasonography
- A small amount of lubricant is applied to the end of the linear – array transducer, which is then inserted in to the rectum.
- The operator‘s index finger maintains contact with the transducer and is used to orient the direction of the scan.
- The transducer is directed ventrally and then rotated approximately 45° to each side.
- Some operators like to stiffen the cord behind the transducer when it is used in this manner by taping a rigid tube around it to provide leverage.
- Urinary bladder is identified as a non-echogenic landmark.
- Gravid uteri are identified by non-echogenic areas, a fluid filled structure anterior and ventral to the urinary bladder.
- Transrectal imaging allows visualization of pregnancies as early as 15 days postbreeding; but routinely observed by 19-22 days post-breeding.
- After approximately 50 days of gestation, fetuses are too large to be completely visualized on the screen. After this stage of gestation, placentomes are the most easily identified cardinal sign of pregnancy.
Trans-abdominal Ultrasonography
- Accurate estimations of gestation length can be made by measuring the biparietal diameter of fetuses between 40-100 days of gestation.
- Gestational age can be estimated within approximately one week by visualization of the diameter of the uterine lumen, crown-to-rump length of the embryo or young fetus or thoracic or skull size of the fetus up to approximately 90 days of gestation.
- Placentome size provides some guidance, but will vary depending on the position of the placentomes scanned in relation to the umbilicus of the fetus.
