Small Ruminant Pregnancy Diagnosis

Missouri Veterinary Medical Association Convention January 27, 2023

Celeste Morris, DVM, MBA, MPVM Assistant Professor, Food Animal Ambulatory Service University of Missouri College of Veterinary Medicine c.morris@missouri.edu

Abstract

This talk includes methods for and timing of pregnancy diagnosis in small ruminants. It will compare and contrast transrectal and transabdominal ultrasonography, discuss fetal counting, pregnancy staging and blood pregnancy testing.

Key Words: Small ruminants, pregnancy diagnosis, transabdominal ultrasound, transrectal ultrasound, pregnancy associated glycoproteins (PAGs), fetal counting, pregnancy staging

Normal Small Ruminant Reproduction Review

Species Estrous Cycle Length Estrus Length Ovulation Puberty Age* Gestation Length CL Dependency

Sheep 17 days (14-19)

Goats 21 days (18-22) 30 hours (15-45 hr) Final 1/3 of estrus (21-45 hrs after start of behavioral estrus) Cycling @ 7-8 months 145-150 days CL dependent days 0 to ~75, then placenta

36 hours (24-72 hr) Variable, 9-37 hours after onset of estrus Cycling @ 6-8 months 150 days (147-155) CL Dependent throughout pregnancy

¥ Seasonally polyestrous (short day breeders) o Deepest anestrus is in April and May o Seasonality varies significantly by breed o Can be manipulated with hormonal protocols ¥ Pregnancy checking often performed from late summer to late winter, but can be year-round depending on the breed and management style of the owner ¥ Classic breeding season is October to December, but can range from August to March ¥ Reproductive anatomy: bicornuate uterus with small uterine body ¥ Gestational anatomy: concave placentomes

More Seasonal Less Seasonal

Goats Nubians Boers Kiko Nigerian Dwarf Goats TN Fainting Goats Sheep Southdown Hampshire Hair Sheep (Equator breeds) Dorset Merino Rambouillet

Methods of Pregnancy Diagnosis

Methods Not Recommended ¥ Presumptive o Non-return to estrus § This may be a good producer tool to help monitor animals and get used to detecting estrus; however, it should not be used for pregnancy diagnosis alone. There are a variety of reasons animals may not come back into estrus (including incorrect owner observations) and some animals can show signs of estrus even if they are pregnant.

o Enlargement of abdomen § Again, this may be a good tool for owners to monitor for general health and well-being, but it should not be used for pregnancy diagnosis. In goats especially, it is not uncommon for them to have a protruding, pendulous abdomen as part of normal anatomy. o Development of mammary glands § This can be used by owners to help monitor progression of mammary tissue, pregnancy, and an indicator of overall health; however, it should not be used for pregnancy diagnosis on its own. Mammary tissue can change significantly in some animals in the absence of pregnancy, and even males can develop seasonally affected mammary tissue (galactorrhea, inappropriate lactation syndrome). o Ballottement § This method has been popular in the past and can be relatively useful in those that are experienced; however, if access to more definitive methods is possible, it should not be used on its own for pregnancy diagnosis. A fetus can easily be mixed up with gastrointestinal contents for an inexperienced examiner and also does not give any information about the health of the pregnancy.

¥ Hormone testing o Estrone sulfate testing § This is a pregnancy specific hormone produced by the placenta; therefore, presence is almost 100% indicative of pregnancy. It can be performed after day 50 of gestation. It is not recommended because few labs perform it and it can be expensive. PSPB (discussed below) is less expensive, more widely available, and can be done sooner. o Progesterone testing § Progesterone is not a pregnancy specific hormone and only indicates that there is a corpus luteum present. Although progesterone is produced by the CL of pregnancy, progesterone testing alone doesn’t distinguish between progesterone from a CL of a normal estrous cycle versus a CL of pregnancy. Progesterone testing is better suited for detecting nonpregnant animals and is effective for this purpose. ¥ Special case – Radiography o Many veterinarians are often comfortable using radiography in general and for pregnancy diagnosis and evaluation in small animals; however, it is not the best method for pregnancy diagnosis in small ruminants. o Finances: Due to financial concerns, it is often not practical for large numbers of animals. o Practicality: If in a clinic, radiography is often easily accessible but it can be challenging in the field and many clinics do not have portable radiography equipment. o Interpretation: Visualization of fetuses, evaluation of fetal and gestational health, and identification of fetal remnants can be difficult due to being superimposed by a large rumen. o Timing: If this is the preferred method by the veterinarian, fetal skeleton is radiopaque by day 65 but best to wait until 90 days to avoid false negatives.

Recommended methods ¥ Pregnancy specific protein B (PSPB), a pregnancy associated glycoprotein (PAG) o Method: PSPB is produced by the placental binucleate giant cells and is produced throughout gestation. It can be detected in blood samples and is pregnancy specific. o Sample: Serum or clotted blood o Timing: 28+ days goats, 35+ days sheep o Idexx kit: ~99% sensitivity, ~93% specificity o Cost: $5-10 depending on the lab, widely available o Challenges: § Can be positive up to 60 days after lambing/kidding § Doesn’t account for fetal viability, health of the pregnancy, or numbers of fetuses ¥ Higher amounts of PSPB frequently means multiple fetuses, but delineation of the amount of PSPB per fetus or counting based on PSPB levels has yet to be established. o How to integrate: § Offer as an option for clients that don’t want to pay for ultrasound (better than nothing).

§ For clients that know how to draw blood, offer as a way to separate pregnant and nonpregnant animals, and then use a follow up ultrasound examination to perform more advanced services (fetal counting, fetal health evaluation, etc, pregnancy confirmation). § Educate clients on how this can help but also the limitations and integrate it in your offerings as another option for management tools.

¥ Ultrasonography o General Guidelines § Bladder is your reference point § Better to wait until at least 42 days to increase chances of fetal survival (or recheck if done early) § Method(s) and timing will change from client to client –need to adapt § Coupling media –methylcellulose (transrectal), alcohol or ultrasound gel (transabdominal) o Ultrasound specifics § Transrectal: linear or curvilinear 5 or 7.5 MHz probe § Transabdominal: Microconvex, 3.5 to 5 MHz ¥ Can also use convex, linear, or transrectal probe depending on goals of examination o Transrectal method § Be gentle, use lots of lubricant § May need to evacuate rectum (fingers) § Can purchase or make an “introducer” to allow more control of the transrectal probe while inside the rectum ¥ Can be made from PVC pipe with probe taped in, just ensure the edges are smooth § Make sure you know where the probe is pointed at all times § Can apply gentle downward pressure to increase visibility § Useful in overconditioned and large small ruminants for whom transabdominal ultrasound may be challenging § Timing: Most appropriate for early pregnancy (~28-60 days) because the pregnant uterus in mid and late gestation moves more ventral and cranial, further away from the rectum, and may be obscured by gastrointestinal contents. o Transabdominal method § Scan from the right side rather than the left to minimize rumen gas interference § Many probe types depending on goal ¥ Microconvex > linear, convex, transrectal § Stand next to (on the right) or behind the animal and hook the probe in the right inguinal area, underneath the inguinal skin flap by the stifle ¥ Can clip small area of hair (~2”x2”) in goats (this is not necessary in sheep and may not be necessary in all goats, always ask owners first) § Scanning in inguinal area starting pointed backward toward the bladder § Scan cranially from bladder to find uterus § Timing: 30 + days through end of gestation Pugh, 2021

Recommended Methods for Small Ruminant Pregnancy Diagnosis

Method Ideal Days Gestation Additional Days Gestation Other Notes

Blood (PAGs)

Transrectal Ultrasound 40+

25 - ~60 Can perform as early as: 28 days goats 35 days sheep Can technically perform at any time beyond 28 days Not within 60 days of last parturition Doesn’t assess fetal health or numbers Difficult in late gestation due to uterine size and relocation to ventral abdominal wall

Transabdominal Ultrasound ~30 – end Fetal counting days ~ 42-58 Becomes more ventral and cranial as the pregnancy is larger (need to scan lower)

Fetal Staging

¥ Fetal age determination o Crown-rump length: Measurement from one end of the fetus (most rostral tip of the head that can be identified, the crown) to the opposite end (rump). o Biparietal diameter: Measurement across the head from the caudal margin of the eye socked on on side across to the caudal margin of the opposite eye socket. It is important to not measure the globes when making this measurement. ¥ Fetal sexing o Timing: 55-75 days (genital tubercle) o Male: The genital tubercle will become the glans penis and therefore will be identified near the umbilicus (the location of the penis in a male animal) o Female: The genital tubercle will become the clitoris and therefore will be identified near the tail (the location of the clitoris in a female animal) Pugh, 2021

Biparietal Diameter

DesCôteaux, 2010

Fetal Counting

¥ Method: o Count either heads or heartbeats – not both o Perform when the fetus is smaller than your probe o Follow all loops of uterine fluid until they join together and then slowly narrow and disappear § If they disappear abruptly, it is likely that you “fell off” the uterus, rather than that you reached the end of the uterine horn to be scanned ¥ Client expectations o Communicate with client that it’s an estimate o Seek feedback for improvement ¥ Timing: Microconvex probe – preferred ~42-58 days (range 42-90 days) o In later gestation, give the information you see but set client expectations ¥ Purpose: Use to guide feeding programs (pregnancy toxemia)

Abnormal Reproductive Findings

¥ Hydrometra: Primarily anechoic fluid distending uterus, no placentomes o Treat with prostaglandin, 10 mg dinoprost or 250 mcg cloprostenol ¥ Pyometra: Primarily hyperechoic or mixed echogenicity fluid distending uterus o Treat with prostaglandin, 10 mg dinoprost or 250 mcg cloprostenol ¥ Mummies: Fetal bones visible with little or no fluid surrounding ¥ Dying/dead/macerated fetuses o Non-viable fetuses (anatomic abnormalities, no heartbeat) o Abnormal appearing fluid o Fetuses of different sizes o Placentome/fetal size mismatch

Small Ruminant Reminders

¥ Some small ruminants (goats > sheep) may exhibit signs of estrus during pregnancy, which is normal ¥ Most common reason for non-cycling small ruminants is pregnancy ¥ Do not induce >5-7 days before due date if viable offspring are expected ¥ Colostrum is ESSENTIAL – no nutrients are passed across epitheliochorial placentas o 10-15% of body weight within 24 hours

Sources

¥ Current Therapy in Large Animal Theriogenology; Elsevier, 2007; ISBN 9780721693231. ¥ Practical Atlas of Ruminant and Camelid Reproductive Ultrasonography; Wiley-Blackwell, 2010; ISBN-13: 9780813815510. ¥ Sheep, Goat, and Cervid Medicine; Elsevier, 2021; ISBN 9780323624633.

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MU-CVM Lectures

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MU-CVM Lectures

Elizabeth A. Giuliano, DVM, MS, DACVO

Professor, Department of Veterinary Medicine and Surgery Section Chief, Comparative Ophthalmology University of Missouri College of Veterinary Medicine Columbia, Mo.

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