Pregnancy Diagnosis By Rectal Palpation in Cattle and Horses | ANS 3319, Lab Reports of Animal Biology

Download Pregnancy Diagnosis By Rectal Palpation in Cattle and Horses | ANS 3319 and more Lab Reports Animal Biology in PDF only on Docsity! ANS 3319C Reproductive Physiology and Endocrinology Pregnancy Diagnosis via Rectal Palpation in Cattle and Horses Objectives 1) To introduce the management practice of rectal palpation for pregnancy diagnosis in cattle and horses and to provide an understanding of why it is used to make management decisions. 2) To provide “hands-on” experience in rectal palpation for pregnancy determination in cattle. Why is rectal palpation used to determine pregnancy status? 1) The primary reasons rectal palpation is used to determine pregnancy status is because it is an inexpensive and highly accurate method of detecting pregnancy at most stages of gestation. 2) The convenience of using ultrasound to detect pregnancy tends to decrease as cattle and horses enter their second trimester of pregnancy. As a result, it is easier and more practical to determine pregnancy using rectal palpation. 3) Pregnancy status can be detected accurately with a lab test in a most large and small animal species. However, this process is expensive and time consuming. Therefore, it is more practical and takes less time to determine pregnancy status by rectal palpation. Why do we want to determine pregnancy status in cattle? 1) Allows for identification of pregnant females to retain in the breeding herd. In order for a cow to be a productive member of the cowherd, she must have a calf about every 365 days. 2) Allows for identification of cows to be culled from the breeding herd including non-pregnant (aka “open”) cows or cows that became pregnant very late in the breeding season. Open cows are unproductive since they will not provide a calf during the next calving period and become an economic liability to maintain until the next breeding season. Cows that become pregnant very late in the breeding season are less productive and have a difficulty having a calf every 365 days. Culling practices such as these are common for beef, dairy, sheep, and swine producers but would not be a common practice in companion animals and horses. 3) Allows producers to better assess of the reproductive performance of their operation. This would include when cows became pregnant during the breeding season, whether there are herd health problems based on the stages of pregnancy and (or) increased number of open animals, or there are sub-fertile bulls resulting in a high percentage of open cows after the end of the breeding season. Why do we want to determine pregnancy status in horses? 1) Allows for identification of pregnant or non-pregnant (open) mares early in breeding season. 2) Knowledge of pregnancy status allows the brood mare manager to cease teasing of mares for breeding purposes, which allows for more efficient use of labor and resources during the breeding season. 3) Provides additional information relative to the reproductive status of the mare based on findings of palpation (i.e., uterine or ovarian status). 4) Allows for identification of twins early in gestation which allows manager to make the decision to eliminate one twin before gestation is too far along. Twins are not desirable in horses. 5) Allows for monitoring of pregnancy during early gestation. If a mare is palpated open, she can be evaluated and rebred expeditiously. 6) Allows for monitoring of pregnancy during mid and late gestation. This is important in mare’s that are known to have had a history of maintaining a late term pregnancy. ANS 3319C Reproductive Physiology and Endocrinology - Pregnancy Diagnosis via Rectal Palpation 2 Methods of Pregnancy Diagnosis: Cattle 1) Milk and Blood Progesterone Tests Measured in blood and (or) milk samples taken 21 to 24 days after a known breeding date. Elevated progesterone concentrations > 1 ng/mL would be indicative of a cow with a CL and possibly pregnant; whereas, progesterone < 1 ng/mL is indicative of no CL present. Milk test results are known within hours but blood test results can take days. The test can lead to false positives due to prolonged luteal phases and retained CL. Therefore, it is not a commonly used management practice. The test is actually more effective in telling you an animal is open due to low progesterone (< 1 ng/mL). 2) Pregnancy Specific Protein B (PSPB) Test Requires a blood sample taken 21 to 24 days after a known breeding date. Elevated levels are indicative of an early pregnancy. PSPB are produced by placenta. Expensive and time consuming process that takes days to get results. 3) Ultrasound Transrectal ultrasonography after day 25 of pregnancy. Results are known immediately. Detection of amniotic vesicle, fluid, fetus, and fetal heartbeat. Sex fetuses from approximately day 55 - 70 of pregnancy. 4) Rectal Palpation Palpation of pregnancy through the rectal/uterine walls. Results are known immediately Technician palpates for fetal membranes, amniotic vesicle, cotyledons and fetus. An experienced technician can determine pregnancy 35 to 40 days after insemination. Methods of Pregnancy Diagnosis: Horses 1) Blood progesterone test Performed 18 to 20 days after known breeding/ovulation dates. Known breeding dates, detect for presence or absence of corpus luteum (CL) Low progesterone (< 1 ng/mL): mare is not pregnant due to lack of CL High progesterone (> 1 ng/mL): mare could be pregnant but can lead to false positives due to pseudopregnancy, retained CL, prolonged luteal phase. 2) Blood test for equine chorionic gonadotropin (eCG) Secretion of eCG by endometrial cups from day 40 to 100 of gestation. Commercial kits used to be available to test for eCG in blood and they are no longer used. Limited usefulness since it will not allow determination of pregnancy < 40 d post breeding. 3) Estrogen concentrations (blood or urine) Estrogens are high in middle/last trimester of pregnancy. The test is done in a lab therefore it takes days to get the results. Cuboni’s test measures presence of conjugated estrogens in urine. Thanksgiving Day Test measures elevated blood estrogens. Typically done to confirm pregnancy in late fall, hence the nickname. 4) Ultrasound Transrectal ultrasonography after day 14 of pregnancy. Results known immediately. Detection of amniotic vesicle, fluid, fetus, and fetal heartbeat. Sex fetuses from approximately day 55 - 70 of pregnancy. 5) Rectal Palpation Palpation of pregnancy through the rectal and uterine walls. Results known immediately. Technician palpates for changes in uterine tone, shape of uterus, and presence and size of the amniotic vesicle. Pregnancy can be determined 20 days after insemination. Figure 1. Side view of where arm is located during rectal palpation of a cow in late gestation (> 200days). Note how the arm is positioned through the pelvic canal and over the brim of the pelvis which allows for palpation of the head of the fetus. This technique also allows the individual to feel for the presence of placental membranes, placentomes, and fluid accumulated within the placenta. The same technique would be used to palpate pregnancies that are shorter in gestation (See Figure 2) where the pregnant tract may actually be sitting in the floor of the pelvis. (Image was taken form The Drost Project Visual Guide to Animal Reproduction). Figure 2. Dorsal view of a pregnant reproductive tract on left and non-pregnant reproductive tract on the right. Note the swelling of the gravid or right horn of the pregnant tract. The swelling represents the conceptus, which contains the placental membranes, fetus, and fluid. Note that the left or non-gravid horn does not have any appreciable fluid accumulation. For the non-pregnant tract, note the absence of swelling of either uterine horn. (Image was taken form The Drost Project Visual Guide to Animal Reproduction). Pregnant Non-pregnant ANS 3319C Reproductive Physiology and Endocrinology - Pregnancy Diagnosis via Rectal Palpation 6 Steps of Rectal Palpation: Horses 1) Physical restraining of mare Make sure that the mare is restrained to provide safety for mare and handlers Prepare tail to keep tail hair out of the way of the palpation process 2) Palpate for anatomical land marks of reproductive tract Remove excess feces from rectum to allow for better palpation of reproductive tract The rectum of the mare is much more sensitive than the cows. Therefore, care must be taken when palpating the mare. Palpation of cervix, uterus, and ovaries Location and size of uterus may provide early indication of pregnancy status 3) Pregnancy staging Day 16 Increased uterine tone with firm and tubular uterus Cervix becomes long, firm and rope-like Day 20 Palpation of embryonic vesicle (30 to 40 mm diameter) Central bulge in uterus, typically located at base of horn Day 28 Embryonic vesicle size of egg Day 35 Embryonic vesicle size of lemon Day 42 Embryonic vesicle size of orange Day 49 Embryonic vesicle size of grapefruit Uterine horns start to loose their tubular tone Day 56 Embryonic vesicle size of cantaloupe Conceptus starts to occupy nearly the entire uterine horn and ½ uterine body Day 60 -100 Uterus increases in size and starts to be drawn over pelvic brim and into abdomen Day 60 conceptus: 12 – 15cm long Day 85 the fetus becomes palpable Day 120 – 150 Fetus is readily palpated Day 150 – 210 Difficult to palpate fetus because it is deep in abdominal cavity.