Columbine Country
Alaskan Malamute Club
|
Columbine Country |
|
|
Below are some interesting articles from Richard Wheeler, DVM who is a reproduction specialist.
THE ELECTIVE (PLANNED)
C-SECTION: How do you make a million dollars
breeding dogs? Start with 2 million
dollars. J
. Breeding dogs is not
cheap…monetarily, emotionally, or with the amount of time invested. Precious lives are involved.
Please breed responsibly. This is the first of a
three part series on C-section delivery in the bitch. My intention is to discuss here the options of Elective
(Planned) C-Sections. Next month I
will cover Emergency C-sections, deciding to proceed to surgery, risks,
consequences, and alternatives. And
finally, I will discuss the C-section itself, anesthesia, and neonatal
resuscitation. The origin of the Cesarean
Operation, Cesarean Section, or C-section is veiled in historic uncertainty.
The procedure is alluded to in Greek Mythology as Apollos delivers
Asclepius from the abdomen of his mother. And
Romans claim the term in memorializing the birth of Julius Caesar.
However, the expression most likely derives from the Latin “caedare:
to cut”. Originally, the
procedure was performed on dead or dying women, sacrificing the life of the
mother in an attempt to save the baby. The
woman, who would eventually die if she was unable to deliver the baby,
subsequently died do to hemorrhage or massive infection before the advent of
sterile surgery or antibiotics. In the bitch, c-sections
are done with the intention of saving the life of the bitch and as many puppies
as possible. Most often, dystocia
(complicated delivery) necessitates an emergency c-section.
By this time one or more of the fetuses may be dead or compromised and
the mother weak or debilitated. 1.)
Predicting dystocia, 2.) Predicting the due date, and 3.)
Planning a Cesarean section
can prevent fetal or maternal loss; and can eliminate midnight emergency calls
to the veterinarian. Predicting Dystocia:
I am not a prophet nor am I
a gypsy; and I do not profess to predict the future. However, I do confess an occasional novena to the gods of
probability. Playing the odds,
Brachycephalic breeds (breeds with
shortened heads/faces such as Bulldogs and Boston Terriers) are at greater risk
of dystocia then other breeds. The
head of the fetus is often too large to pass through the pelvis of the dam, and
lacks the traditional missile-shape which helps to direct the fetus through the
cervix and the pelvis. If I were a betting man, I
might also wager that a bitch which has had a previous c-section will likely
fail to deliver subsequent litters naturally.
So-called “V-BAC” (Vaginal Birth After C-section) in human medicine
is discouraged in canine obstetrics. Post-surgical
adhesions and scar tissue may inhibit normal uterine contraction, preventing
fetal expulsion. Further, we
anticipate that the cause of the initial dystocia may recur during future
pregnancies. This is especially true of “failure to initiate labor”
(technically, Primary uterine inertia),
or a developmental abnormality of the bitch’s reproductive tract which
obstructs passage of the fetus (eg. broken
pelvis, vaginal stricture, vaginal scarring, etc.).
Occasionally very large
litters will be surgically delivered to eliminate the risk of maternal
exhaustion and failure to deliver all of the puppies (technically, Secondary
uterine inertia). Conversely,
breeders faced with very small or single pup litters may elect for cesarean
delivery to prevent potential dystocia and loss of very valuable pups. Predicting the Due Date: Puppies require very
precise determination of the due date for survival.
They will not survive if they are born even 2 days pre-maturely. Again, I do not possess a
crystal ball. Accurate prediction
of the due date relies on hormonal evaluation of the bitch BEFORE BREEDING.
If an owner determines for any of the above reasons that the bitch will
require a cesarean delivery, they should consult a veterinarian to coordinate
the breeding with hormone and cytologic evaluation.
Serial blood progesterone or blood lutenizing hormone (LH) measurements
allow accurate prediction of whelping date.
Whelping occurs 65 days after the LH peak, with a variability of 1 day. Armed with this information, your veterinarian can
confidently schedule a daytime surgery and safely deliver the pups. If the rise in LH was not
determined, it is impossible to safely schedule a planned c-section.
That is not to say, however, that the bitch must commence labor before
surgery. Your veterinarian can
roughly estimate the due date based strictly on cytology, determining the first
day of Diestrus (last day of heat). Whelping
will occur 57 days after the change in cytology with a variability of 3 days
(outside the safety range of 2 days to surgically deliver viable pups).
Fetal gestational age can also be calculated by ultrasound measurements
during early pregnancy (~day 25-35); again, variability is at least 3 days.
As the estimated due date approaches, the breeder must monitor the
bitch’s progress through pregnancy, mammary development, nesting behavior,
drop in temperature, and loss of appetite.
Then blood progesterone level can be evaluated.
When it drops below 2 ng/ml it is safe to proceed to c-section.
Less preferably, a
“planned” c-section can be initiated when the first signs of labor are
detected. However, it now becomes
an unscheduled, emergency c-section. Failure
to initiate labor or delay in performing the c-section risks the loss of part or
all of the litter. Obviously, a little
forethought provides a greater safety net and ultimately less stress for the
breeder, the surgeon, and the mother-to-be. Cesarean Section: C-section circumvents the
risk of dystocia during vaginal delivery, all but guaranteeing the safe delivery
of the entire litter. The bitch enjoys decreased duration of labor, decreased
physical exertion, and the benefits of analgesia.
The breeder forgoes whelping anxieties. And
cost-benefit analysis will reveal that preventing the loss of even one puppy
compensates the expense of the timing and the surgery. Given all these wonderful
benefits, why aren’t all whelpings scheduled for elective c-section?
The answer to that question
is a moral conundrum. Once the
monetary component is eliminated, it becomes a question of ethical
consideration. 90% of natural
deliveries progress without complications.
Therefore, elective C-section of all pregnant bitches necessitates 90% of
the bitches enduring unnecessary surgery. Is
it worth the risks of surgery to avoid potential complications in 10% of
pregnancies? Bulldog breeders have
determined that elective c-sections are essential to the breed, their dystocia
rate, however, exceeds the 10% natural average.
Summary: Scheduled C-sections are
often a feasible and economic option to guarantee delivery of the greatest
number of healthy, viable puppies and preserving the life of the dam.
A well established veterinary-client relationship should be developed,
and forethought and excellent breeding management should be followed to ensure
the greatest success. Richard Wheeler, DVM,
Diplomate ACT (Board Certified, Reproduction) Poudre River Veterinary
Clinic Affiliate:
CSU Veterinary Teaching Hospital Fort Collins, CO THE EMERGENCY C-SECTION: Breeding dogs is not cheap…monetarily,
emotionally, or with the amount of time invested. Precious lives are involved.
Please breed responsibly. This is the second of a
three part series on C-section delivery in the bitch. My intention is to discuss here Emergency C-sections,
deciding to proceed to surgery, risks, consequences, and alternatives.
Next month, I will discuss the C-section itself, anesthesia, and neonatal
resuscitation. Innumerable conceivable
(and some inconceivable) situations can arise to prompt an emergency c-section.
Below are a few plausible situations to consider.
In reality, each situation will be different and multiple factors
involved which must be considered in making the decision to proceed to surgery.
A
bitch is perceived to be “overdue”.
Very rarely will a bitch actually exceed normal canine gestation. The problem is determining “normal”. Often, the gestation period of the dog is arbitrarily
designated as 65 days. Or 62 days.
Or 57 days. Even as long as 72 days.
Such variability makes it impossible to predict whelping based on breeding
dates. Determining the first
day of Diestrus (D1) with vaginal cytology allows more accurate prediction
of whelping 57 days later. Even
then, there is a variability of 3 days (remember, as we discussed previously,
delivery even 2 days premature rarely results in viable puppies).
The greatest accuracy in estimating whelping date is 65 days after the Lutenizing
Hormone (LH) peak, determined by either serial blood progesterone or LH
evaluations. This provides accuracy within 1-2 days of whelping.
Ultrasound estimation of fetal age base on fetal measurements in
early gestation can improve accuracy to within 1 day when combined with the LH
peak. A
bitch’s temperature will commonly drop 1-3 degrees below its normal range
(usually to 98 or 99 degrees Fahrenheit) 24 hours before whelping.
This temperature drop is a result of a sudden drop in Progesterone, the
hormone responsible for maintaining pregnancy.
Bitches will also often go off feed the morning prior to delivery.
If a bitch exceeds her expected due date or there are no signs of labor
within 24 hours of an obvious temperature drop, Primary
Uterine Inertia (PUI) should be
considered. PUI is a condition in
which the uterus fails to contract sufficiently to elicit labor or deliver the
puppies. Causes of PUI are poorly
understood, but included chemical imbalances (especially calcium or magnesium),
poor quality nutrition (which may result in chemical imbalances), excessive
uterine stretching (possibly from very large litters or abnormal fluid retention
called Hydrops), or most commonly for
no apparent reason at all (Idiopathic PUI—which
may be genetic and is likely to recur on subsequent litters). Failure to initiate labor
is another possibility for an overdue bitch.
It is poorly documented, but clinical impression suggests that very small
or singleton litters lack sufficient fetal input to trigger the hormonal changes
necessary to initiate labor. Whatever
the cause, adjunctive diagnostics are warranted to determine if whelping is
eminent to prevent delivery of premature puppies. Blood progesterone levels and fetal monitoring (by
ultrasound) are most critical. Accurate
breeding history, especially LH peak, is also very valuable. Occasionally,
medical intervention will suffice, including calcium or magnesium
supplementation. However, most
commonly, surgery is required. Administration
of oxytocin is rarely successful in treating PUI, and is CONTRAINDICATED in the
event that the cervix has not dilated. Dystocia
is the malpositioning or oversize of a puppy which prevents normal delivery.
Active abdominal pressing and straining for more than 20 minutes without
producing a puppy is highly suggestive of a dystocia.
Possible situations causing dystocia include a puppy too large to fit
through the birth canal, 2 puppies entering the birth canal at the same time,
abnormal formation of the puppy, abnormal position of the puppy (side-ways in
the birth canal or head bent down in the birth canal).
Diagnosis
of the cause of dystocia requires vaginal examination and often X-rays.
If the puppy is within the birth canal, occasionally vaginal deliver with
ample lubrication and gentle traction is successful.
If the puppy cannot be delivered within 30 minutes, C-section is
recommended. THE USE OF OXYTOCIN IS
CONTAINDICATED IN RELIEVING DYSTOCIA. Stimulation
of uterine contraction will increase the pressure against the puppy and may
damage the uterus. Increasing
uterine contractions will also decrease oxygen perfusion to the remaining
puppies. Secondary Uterine Inertia (SUI)
is a condition in which the uterine muscles become exhausted and can no longer
contract enough to deliver the puppies. SUI
often occurs with persistent contraction during dystocia.
It may also result during the delivery of the last puppies in a large
litter. This is the only
situation, in my opinion, where oxytocin is warranted.
And then, if and only if it is certain that the cause of SUI is NOT
DYSTOCIA. Calcium supplementation
is often necessary in conjunction with oxytocin.
If SUI occurs with 3 or more puppies remaining in utero, it may be
reasonable to proceed to c-section, as delayed delivery of the remaining puppies
may result in fetal hypoxia (suffocation) and death. Premature placental separation is
suspected with the appearance of greenish-black vaginal discharge (Uteroverdin)
without delivery of the first puppy. THIS
IS AN EMERGENCY! It may be a
consequence of PUI or secondary to a dystocia.
In either event, at least one and possibly all puppies have decreased
oxygen delivery and will soon suffocate. Further
diagnostics are seldom warranted and immediate c-section is recommended.
Passage of uteroverdin after the first puppy cannot be differentiated
from the initial discharge and therefore cannot be used to interpret placental
separation later in delivery. In
choosing to proceed to Emergency C-section, it is necessary to determine the
risk to the puppies and to the bitch. Maximizing
live births is the goal, and the sooner a diagnosis can be made, the better.
Proper diagnosis of the cause of failure to deliver utilizing blood
chemistry and progesterone, ultrasound, and x-ray, greatly hasten the decision
to proceed to surgery. Medical
management of C-section with calcium, oxytocin, and manual extraction can be
rewarding. However, if several
puppies remain in utero when intervention is needed, repeated attempts at
non-surgical deliver may be too time consuming and stressful to the bitch and
the unborn puppies. Richard Wheeler, DVM,
Diplomate ACT (Board Certified, Reproduction) Poudre River Veterinary
Clinic Affiliate:
CSU Veterinary Teaching Hospital Fort Collins, CO (970) 227-2320 THE
C-SECTION: Breeding dogs is not cheap…monetarily,
emotionally, or with the amount of time invested. Precious lives are involved.
Please breed responsibly. As a breeder you may have
been or will be faced with the decision to proceed to C-section for management
of a whelping bitch. For those of
you who would like me to give you the definitive answer as to when to proceed to
c-section, proper anesthetic protocol, and best surgical approach; I am sorry to
inform you that there are too many variables and too many options for one simple
answer. Veterinarians experienced
in dystocia management and cesarean delivery are perhaps the single most
importantly factor for a successful outcome.
Expedient delivery increases the survival of pups., shortening the
duration of surgery and minimizing the potential for complications. Fetal oxygenation is the
foremost liability during the operation. All
anesthetic and surgical decisions pivot around fetal oxygen delivery.
Without oxygen, puppies suffocate or become severely debilitated and
expire soon after delivery. Fetal oxygenation can be
affected in 3 ways; first, decreased
maternal blood flow to the uterus. Uterine
blood flow is primarily affected by blood pressure, either being too high or too
low. Low blood pressure routinely
occurs with the use of any anesthetic. To minimize this effect, maintain the lowest level of
anesthesia possible and avoid sedatives such as Acepromazine.
Fluid administration before induction of anesthesia and during the
surgery will also help maintain normal blood pressures.
Finally, avoid hypothermia; low body temperature contributes to low blood
pressure. Anxiety, stress, and pain
result in high blood pressure which also decreases perfusion of the uterus.
Sedation of animals can minimize this effect but should be done
judiciously so as not to adversely affect the fetuses.
Avoid use of Xylazine (which
increases blood pressure), and Acepromazine (as previously mentioned). Opioids (morphine derivatives) are the sedative of choice.
Further, hyperventilation of the dam increases blood pressure and should
be avoided. Second,
fetal oxygenation can be affected by decrease concentration of oxygen in
the dams blood. This can occur if
the dam stops breathing or is unable to take deep breaths.
Pre-oxygenating the bitch for 3-5 minutes with 100% oxygen before she is
anesthetized maximizes the oxygen concentration in her blood.
Positioning the bitch at an angle on her right side (as opposed to
directly on her back) will facilitate blood flow to her heart and lungs for
re-oxygenation. And administering a deep breath occasionally to the bitch
with the ventilator will also improve oxygenation during surgery.
Because
it is impossible to directly measure fetal oxygen status, monitoring the blood
pressure of the dam and oxygen saturation of her blood provides appropriate
estimations of fetal oxygen perfusion. Many
veterinary clinics are capable of evaluate these vital signs with capnographs,
oxymeters, and blood pressure monitoring equipment. Third,
fetal oxygenation is affected by the fetuses’ ability to breathe at delivery.
Use of Xylazine and/or Ketamine
have been associated with decrease puppy survival, presumably from residual
effects on the puppies delaying spontaneous respiration.
Stimulation of fetal breathing is best accomplished using gentle, yet
vigorous stimulation in towel drying.
Clear the airway using an infant suction bulb or a dry cotton-tipped
swab, as opposed to swinging the puppy; which may result in neck or head trauma
or regurgitation and aspiration of stomach contents.
Warming the puppy with a warm hair dryer, incubator, or radiant heat
source will also facilitate respiration. If
the puppies do not begin breathing within 30 seconds, or the heart rate begins
to decrease, provide supplemental oxygen, and attempt positive pressure
ventilation with a face mask or intubation.
Stimulation of the acupuncture point at the juncture between the base of
the nose and upper lip using a 25 gauge needle with rapid, pecking motions may
also stimulate respiration. If the
heart rate continues to drop and breathing does not ensue, administration of
Epinephrine is warranted. Routine
use of Doxipram is not advocated: it
has not been proven to be efficacious, and may cause cardiac infarction.
Recent studies demonstrate
that no single anesthetic drug is superior to another in affecting survival of
puppies; with the exception of Xylazine and Ketamine mentioned above.
My preferred anesthetic protocol is Propofol induction with gas
anesthesia using either Isoflurane or Sevoflurane. There is no single surgical
approach which has been proven more effective then another.
The important factor is that the surgeon is competent at the approach
s/he elects to use. If hysterectomy
(spaying) is elected or required (because of uterine rupture or uterine artery
rupture) at the time of c-section, fastidious attention must be paid to ligation
of engorge uterine vessels. There
is no consequence to the bitch or the puppies if spaying is accomplished at the
time of delivery. Anecdotal reports
of decreased lactation have been reported; but have no physiologic substance.
If the owner elects to delay spaying the bitch, my recommendation is to
proceed with the subsequent surgery after weaning the pups and before the next
heat ensues. Post-operatively, greater
puppy survival is achieved when the bitch is alert and attentive to the puppies.
Maternal stimulation of urination, defecation, nursing, activity and body
heat are critical. To this end,
decreased exposure to sedatives and anesthetics by lowering doses and decreasing
surgery time are most beneficial. Second,
use of post-operative analgesics provide pain relief so the bitch will allow the
puppies to nurse and be attentive to them.
Intra-operative administration of opioids, or post operative use of
non-steroidal anti-inflammatories are most effective. Local infusion of a line block over the incision site may
provide temporary relief. Richard Wheeler, DVM,
Diplomate ACT (Board Certified, Reproduction) Poudre River Veterinary
Clinic Affiliate:
CSU Veterinary Teaching Hospital Fort Collins, CO
|
|
Send mail to mals@malpaws.com with
questions or comments about this web site.
|
