Overdue Pregnancies

11-18-04

Overdue Pregnancies in alpacas and llamas Overdue Pregnancies in alpacas and llamas

Overdue Females and Females with Problem Pregnancies

David E Anderson, D.V.M., MS, Diplomate ACVS
Ohio State University, Columbus, Ohio

Assessment of fetal well-being is an area of on-going research. We are
particularly interested in predicting or determining fetal stress so that
treatments aimed at preventing abortion or pre-mature birth. This
information would allow us to "prophylactically" apply these treatments
in females speculated to be "at risk".

Behavior of the Dam - The behavior of the dam must not be under emphasized.
If the dam is behaving normally, eating normally, and no changes in routine
have been observed, then most likely the fetus is fine. We consult with many
owners about "overdue" birthing. Many of these females ultimately are found
not to be pregnant. Occasionally, prolonged gestation does occur in llamas
and alpacas and the causes are not well understood. Our protocol for
evaluation of females that are 11.5 months or longer in gestation is to
perform a complete physical examination, rectal and vaginal examination,
ultrasound examination, and fetal heart rate assessment. If the dam and
fetus are normal in all respects, then the pregnancy is allowed to continue
undisturbed. Using this protocol, we have had excellent success with healthy
neonates being born. Occasionally, an abnormal or stillborn cria is born,
but these are far outnumbered by the problems caused by premature
termination of pregnancy. The problem is knowing what is "normal" with these
tests and how to conduct them.

 
Rectal, and Vaginal Examination - Rectal palpation is often difficult in
alpacas because of their small size, but most mature llamas can be palpated
if proper pre-cautions are observed. A solid sided llama or alpaca restraint
chute is important to allow easy and efficient reproductive examinations.
Performing these diagnostic tools on free-standing females or females
pressed against a wall are stressful for the patient, veterinarian, and
owner. Sedation should be used sparingly. When needed, butorphenol tartrate
(0.1 mg/kg IV or IM) provides excellent sedation with minimal to no untoward
effects on the fetus or dam. Before rectal palpation, I prefer to place 60
to 100 ml of lubricant into the lumen of the rectum. In small females, 10 ml
of lidocaine can be added to help relax the anal sphincter. Rectal palpation
should be performed with caution because rectal tears have been reported to
occur in llamas. The examiner should make the owner aware that bleeding from
the anal sphincter is common when rectal palpation is performed. This is
caused by over-stretching of the mucous membrane and sphincter muscle. This
does not pose a risk to the animal in most cases (I have never seen a
complication from mild anal sphincter bleeding). Rectal examination should
be used to assess fetal movement, uterine tone, position of the broad
ligaments (rule out uterine torsion), and the presence of adhesions or other
periuterine masses. An interesting observation is that we have found the
head and front limbs of the fetus within the pelvic canal up to 3 months
before parturition. Also, we have failed to find the head and feet of the
fetus within the pelvic canal as early as 3 days before parturition in
llamas and alpacas to whom the cria was ultimately delivered in a normal
anterior, longitudinal, dorsosacral position. Using these qualitative
methods, we can say that the fetus is alive, but no definitive comment can
be made concerning fetal stress. Vaginal examination will allow assessment
of the cervix for inflammation, discharge, and the presence of the mucous
plug. If the cervix is closed and no discharge is noted, then we can say
that all appears normal, but no definitive statement can be made concerning
fetal stress.

Hormonal Tests - Many owners and breeders have relied upon serum
progesterone concentration to assess pregnancy status. We have not found an
association between fetal stress and serum progesterone status, but we have
not had the opportunity to perform serial assays on "at risk" females. My
opinion is that a sudden decrease in serum progesterone would be found too
late for effective treatment to be initiated. No "llama or alpaca side"
progesterone test has been developed to date. However, we have conducted
research correlating serum progesterone assays with the commercial test kits
available for canine (Target Canine Ovulation Timing Kit, BioMetallics,
Princeton, NJ) and equine (Target Equine Breeding System, BioMetallics,
Princeton, NJ) progesterone (Table 1). In our study, we found the equine kit
was more consistently correctly interpreted, but the accuracy of the tests
is broad (C2/3 range = 1 to 5 ng/ml).

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Table 1. Serum progesterone concentration study comparing results of
laboratory RID with that of canine-side and equine-side test kits.
----------------
Camelid    Laboratory Assay    Canine Kit    Equine Kit

1                1.5                            C3*                  C2
2                1.42                          C2                    C2
3                1.4                            C2                    C2
4                0.33                          C2*                  C1
5                0.09                          C2*                  C1
6                0.04                          C2*                  C1

Target Equine Breeding System: C=0-1 ng/ml; C2/3= 1-5 ng/ml; C4= > 5ng/ml
Target Canine Ovulation Timing Kit: C1= 0-1 ng/ml; C2=1-2.5 ng/ml; C3= 2.5-5 ng/ml;
C4 = >5 ng/ml
* indicates false positive test result
-------------------------------------------------------------------------------------------

Ultrasonography -  Ultrasonography is useful for non-invasive evaluation of
the intrauterine environment and fetus. This is the mainstay of our current
state-of-the-art evaluations. If the fetal thorax and heart can be seen, the
fetal heart rate (FHR) can be counted. I routinely use a 5 MHZ linear
transducer for evaluation of all stages of pregnancy (approximately 12 to 15
cm penetration of adequate resolution images). A 3.5 MHZ transducer can be
used for deeper penetration of the abdomen (up to 20 to 23 cm), but
significant loss of image resolution occurs at these depths. Most modern
ultrasound machines are equipped for simultaneous B- and M-Mode
ultrasonography. This allows assessment of fetal heart rate and some
quantitative estimates of cardiac contractility. If the uterine fluid
appears normal, then we would assume that the fetus-placenta-dam unit is
normal. The placenta can be evaluated to a certain extent and premature
separation of the placenta or placental edema may be found in females having
had a uterine torsion. These findings suggest that a C-section may be
necessary to save the life of the cria. If the FHR is normal, we would
assume that the fetus is normal (adequate oxygen supply and waste removal).
In our fetal stress research, we have determined that normal fetal heart
rate range for alpacas and llamas is 80 to 120 (fetal heart rate ranges from
1.5 to 2.0 x maternal heart rate (MHR)). The late gestation fetus (> 6 to 7
months) is positioned in the uterus with the fetal head and thorax located
near the maternal xiphoid bone just to the right of midline. Thus, the hair
may need to be clipped to allow ultrasonography of the fetal heart. Most
owners do not object to having this done because this region of hair removal
is not seen and is not economically important. Occasionally the fetal heart
can not be found because of fetal positioning (fetal backbone or maternal
viscera obstruction of ultrasound waves, positioning too deep in the abdomen
for viewing, etc). Also, we have seen fetal ultrasound examinations where
there was no apparent heart beat, but the fetus was alive and was normal at
birth. Thus, fetal heart ultrasound images must be interpreted with caution.


 
Fetal ECG - In our early research to establish a tool for assessment of
fetal stress, we attempted to perform fetal ECG. This technique has been
used successfully in horses to assess fetal heart rate and rhythm. We used
several models of ECG machines including a physiograph with high sensitivity
leads and were unable to consistently record fetal ECG patterns. In the
llamas and alpacas we tested, the fetal complexes were only intermittently
recorded and were usually buried within maternal complexes such that they
were unrecognizable. Rarely, we could obtain a clear ECG complex, but we
were not able to determine rate or rythm in any fetus. We concluded that
fetal ECG's are seldom successful because of the size of the abdomen,
position of the fetus, low magnitude of fetal complexes, and the
overwhelming ECG of the dam. To date, we have not been able to record any
diagnostic fetal ECG segment.

Fetal Cardiotocography - Recently, we have been investigating the use of
fetal Doppler ultrasound for assessment of fetal well-being (Fetal Monitor
155, Corometrics Medical Systems, Inc, Wallingford, Conn, USA). The Fetal
Heart Monitor records fetal heart rate and heart rate variability (external
Doppler probe), and uterine contractions (external probe with pressure
sensor). Jonker has published a text on cardiotocography in cattle. This
text is recommended reading for those interested in developing skills in
fetal heart monitoring. Rabello and Lapidus published a text on electronic
fetal monitoring in humans and this text is highly recommended for knowledge
of techniques for assessment of fetal stress. The Corometrics unit has the
ability to record FHR and uterine activity pressure waves in humans. To
date, we have not been able to successfully record diagnostic uterine
activity tracings because of interference by forestomach motility, maternal
movement, fetal movement, and the maternal abdomen geometry. However, we
have been able to consistently and reliably record fetal heart tracings to
assess rate and variability. Based on Doppler ultrasound recordings of fetal
heart rate, we determined that FHR is expected to be between 80 and 120
(roughly 1.5 to 2 times the MHR). However, the normal fetal heart rate is
not consistent from moment to moment. We have identified three fetal heart
rate patterns: 1) low frequency undulation, 2) sudden acceleration followed
by deceleration, 3) no undulation. Based on our clinical research, low
frequency undulations are the normal pattern for gestating fetuses of llamas
and alpacas. At this time, we are not certain about the significance of
rapid accelerations and decelerations or the absence of undulation. I feel
that the absence of undulation may represent periods of fetal quiescence and
are not abnormal unless they are associated with low heart rate (FHR < 60).
The only FHR's that we have seen that were consistently below 60 were in
dams with severe illness and the cria ultimately were delivered by C-section
or were aborted. Rapid acceleration and deceleration have been reported to
occur in cattle, but were uncommon. These periods may be associated with
sudden fetal movement, maternal excitation, uterine contraction, or unknown
stimuli. We have observed this pattern in only one alpaca and the recording
was obtained 2 days after non-surgical correction of a uterine torsion. In
that alpaca, we elected to perform a C-section because of concerns for fetal
stress. At surgery, premature separation of the placenta seemed to have
occurred but a live male cria was delivered. This episode of sudden FHR
acceleration was thought to have occurred because of developing fetal
hypoxia.

References

Jonker FH. Cardiotocographic monitoring of the bovine fetus. University of
Utrecht (ISBN 90-393-0425-4) 1993 (171 pages).

Rabello YA, Lapidus MR. Fundamentals of electronic fetal monitoring.
Corometrics Medical Systems, Inc, Wallingford, Conn. 1988 (162 pages).

Deans AC, Steer PJ. The use of the fetal electrocardiogram in labor. Br J
Obstetrics and Gynecology. 1994;101:9-17.

 
Jonker FH, van Oord HA, van Geijn HP, et al. Feasibility of continuous
recording of fetal heart rate in the near term bovine fetus by means of
transabdominal Doppler. Vet Quarterly 1994;16:165-168.

Jonker FH, van Geijn HP, Chan WW, et al. Characteristics of fetal heart rate
changes during the expulsive stage of bovine parturition in relation to
fetal outcome. Am J Vet Res 1996;57:1373-1381.

Cohen S, Mulder JH, van Oord HA, et al. Noninvasive monitoring of fetal
heart rate during the last ten days of gestation in sows. Am J Vet Res
1997;58:1285-1290.


 David E Anderson, DVM, MS
 The Ohio State University
         http://www.vet.ohio-state.edu/docs/ClinSci/camelid/index.html
         http://www.internationalcamelidinstitute.org

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