Major
Events of Pregnancy
Some of the major events of pregnancy in the dog include
the following, based on previous reviews and reports [1-8].
Entry of embryo into uterus around Day 11; implantation
around Day 22 - 23; secretion of relaxin by the placenta
by Day 24 - 28 and through term; increased secretion of
prolactin by Day 30 and through term and lactation; a physiological
normocytic anemia evident by Day 30 or 35, and maximal (with
hematocrit reduced to 30 - 40%) at term; slightly increased
secretion of progesterone from Day 30 through term, probably
due to the increase in prolactin secretion (since prolactin
is luteotrophic); a simultaneous increase in metabolism
and fecal excretion of progesterone such that serum progesterone
concentrations do not rise much higher than in nonpregnant
bitches; an acute pre-partum rise in prostaglandins to luteolytic
concentrations and a resulting rapid decline in progesterone
concentrations during the 24 h pre-partum; a corresponding
pre-partum behavior of nesting, digging, social withdrawal,
defensiveness, and, also a corresponding drop in rectal
temperature of 1oC, or more; pre-partum and peri-partum
discharge of normal green lochia; delivery (whelping) of
pup(s) with an average size litter taking 4 to 24 hours.
Timing
Events of Pregnancy
The time-course of
events of canine pregnancy that have been carefully studied
all appear to be relatively consistent among bitches and
predictable when timed correctly. Timing can be accomplished
based on the following, listed in the presumed order of
reliability:
1. the day of the ovulatory LH surge determined by serum
LH assay;
2. the day of the LH surge as estimated by the detection
of the concomitant rise in serum progesterone by radioimmunoassay
or sensitive ELISA;
3. the day of ovulation (Day 2) as estimated by ultrasound;
4. the day of LH surge and/or day of ovulation based on
commercial ELISA progesterone assay;
5. day of LH surge based on commercial urinary or serum
LH assay;
6. day of LH surge and/or ovulation based on the end-of-estrus
(metestrus or diestrus) change in vaginal cytology;
7. day of ovulation based on changes in the vaginoscopic
appearance of the vaginal mucosa; or,
8. day of ovulation based on the timing of the pre-ovulatory
softening of the vulva and perineum.
Time
Course of Gestational Events and Clinical Landmarks
When the day of the preovulatory
LH surge has been determined directly or based on radioimmunoassay
of the initial increase in progesterone in samples collected
daily or more frequently, the sequence of events that has
been observed (or estimated) has typically been consistent
across studies, and are reviewed in Tables 1 and 2. However
there have been some variation and minor differences noted
among studies [typically 1 - 2 days] when studies have been
done using a pre-defined, absolute concentration of progesterone
to estimate the time of ovulation. The day of parturition
can be predicted to be 65+/- 1 days after the estimated
day of the preovulatory surge in LH with a reasonable degree
of accuracy if effort has been placed on accurate estimation
of the day of the LH surge. The timing of other events of
gestation are also predictable.
Impending
Parturition and Elective Caesarian Sections
Pre-planned
or elective c-sections can probably be performed safely
after Day 63 after the LH surge. However, there are no clinical
research reports to this effect and special concern for
support of the pups is important. In other than brachycephalic
breeds, waiting until Day 65 or 66 may result in spontaneous
delivery and obviate the need for c-section. In brachycephalic
breeds initiation of surgery before natural labor may be
important, although there are no published data on the incidence
of problems during natural delivery in these breeds. Elective
and emergency c-section is extremely safe as performed in
the United States and Canada [5]. The pup mortality was
the same as, or possibly less than, that observed with natural
delivery, and bitch mortality was 1%. The possible value
of pre-surgical administration of dexamethasone has not
been reported, but there is anecdotal evidence of its successful
use in some practices. The intention is apparently to mimic
the natural rise in corticosteroid that likely occurs at
normal parturition. There is also anecdotal evidence that
incidence of prematurity, irregularities of fetal heart
rates, and neonatal deaths can be reduced by first confirming
that the bitch is at term by assay of serum progesterone,
but no reports have been published. It is reasonable to
suggest that at the time of surgery progesterone should
be low, and preferably near or below 2 ng/ml, i.e. at levels
expected within 24 h before natural labor. The same ELISA
progesterone kits used to monitor
ovulation can be used in this regard.
Serum progesterone
is at peak concentration between Days 15 and 30, and may
reach peaks as high as 80 ng/ml (240 nmol/L ) or as low
as 15 ng/ml (45 nmol/L ). In late gestation, Day 50 - 60,
progesterone can be as high as 15 ng/ml (45 nmol/l ) or
as low as 3 ng/ml (9 nmol/L ). Progesterone typically declines
from 4 - 5 ng ml ( 12 - 15 nmol/L) to near or below 2 ng/ml
(6 - 7 nmol/L) during the 24 h before the onset of labor.
There is a concurrent pre-partum decline in body temperature
which is most readily observed with twice daily or more
frequent rectal temperature measurements started several
days before parturition. Many practitioners routinely have
dog owners measure and record rectal temperatures 2 or 3
times a day starting 1 week before
the predicted date of whelping.
Managing
and Timing Pregnancies When Day of Ovulation is Unknown
The stage
of pregnancy can be estimated based on several parameters.
In recently bred bitches a vaginal smear can determine if
the transition from estrus to metestrus(diestrus) has occurred.
This transition or shift in the composition of the smear
typically occurs 7 - 9 days after the LH surge, and thus
about 57 days pre-partum. It is not entirely accurate in
that the metestrus or diestrus shift in the smear can occur
as early as Day 6 and as late as Day 11 (Concannon and Shille,
unpublished observation). In early pregnancy, the size of
uterine enlargements palpable per abdomen can be helpful,
being typically 1 cm at Day 22 - 24, and 3 cm at Day 32,
post LH surge. Ultrasound studies at know times relative
to the LH surge have described several sonographic landmarks
of fetal development that can be used to estimate the stage
of gestation when the day of the LH surge is not known or
accurately estimated. [7-10] Using ultrasound, the time
of early detection of heart beat depends on instrumentation,
experience and preparation of the abdomen. However they
are never detectable before Day 23 and are likely to be
detectable with any instrument by Day 28 - 30. The fetal
length in relation to the length of the placental girdle
can be determined by ultrasound and results related to Day
40 - 42, when the fetus crown-rump length becomes longer
than the placental girdle. Details of other ultrasound criteria
have been reported [7-10], including first detection of
the fetal limb buds at Day 33 - 35; eyes, kidney and liver
at Day 39 - 47; and intestine at Day 57 - 63. With radiography,
the fetal skull is rarely visible before Day 45 and is almost
always visible by Day 47 - 49; pelvic bones are not visible
before Day 53 and are usually easily seen by Day 57; fetal
teeth, not before Day 58 and usually by Day 63.
Signs
of Pregnancy
My dogs give
me signs, shortly after breeding to let me know that they
are pregnant. Yours will too. You just need to know how
to recognize the signs:
1. Her vulva will stay slightly swollen after their heat
ends.
2. Her teats ( nipples will be more pronounced and hard.
3. You will notice a big change in her temperament. She
may get quieter or lazy or more loving
>4. 2 weeks after breeding they may experience morning
sickness. It can last a week or so. Give her saltene crackers
before she gets out of bed and a few throughout the day
By now I know they are pregnant.
Your vet has to wait until day 28-32 of her pregnancy, to
palpate the abdomen.
To do this lay your dog on her side, slide one palm beneath
her and your other palm over her other side, just below
her ribs. Gently squeeze your palms together and feel for
little golf balls, these are puppies. If you become good
at this, you will be able to count the puppies.
5. In the
4th week you may notice thickening of her sides, between
her ribs and hip bone.
6. She may start to show any time after 5 weeks. Larger
breeds may carry the pups up in her rib cage so it might
not be so easy to notice.
7. Most dogs show at 6-7 weeks. You may notice a normal
discharge somewhere in the last couple of weeks. The discharge
is clear and has the consistency of thick vaseline and is
oderless.
If you notice a discharge that is green or bloody and fowl
smelling seek a vet.
8. In the 8th
week you can fell the puppies kick and turn around. I just
love this part.
9. If you own a stethoscope
you can hear heartbeats in the 8th week. It sounds like
short quick tic,tic,tic,tic,tic. I have learned to tell
a sex of pup this way. Males tic faster. Like in Morris
code, males are the dot, females are the dash.
You can count pups too.
10. Its safe to get an x-ray in the 8th week, but not just
to count pups. Do it only if you suspect she may have a
small birth canal which may present a problem.
11. In the 9th week her belly will start to change shape.
It appears to lay lower to the ground. This is caused from
the pups lining up in the uterine horns. In a human is called
when the belly drops.
The 9th week lasts
forever, by now you should have started recording her temperature,
and have all your whelping supplies on hand. Her bed needs
to be ready for the big day.
