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Canine Pregnancy: Predicting Parturition and Timing Events of Gestation


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Introduction Many aspects of canine pregnancy are unique among veterinary domestic species. Therefore, an understanding of the time course and clinical correlates of ovulation, fertilization, embryo and fetal development, and pregnancy specific changes in maternal physiology is essential when providing clinical services such as breeding management and monitoring of pregnancy [1-4]. It is also important for decision-making in cases of pregnancy failure, elective caesarian section and dystocia. One important fact is that gestation length and events of gestation are very repeatable and predicable when viewed in relation to the time of ovulation or the preceding the luteinizing hormone (LH) surge (Table 1 and 2). That is true, despite the fact that the normal interval from breeding to whelping can range from 55 to 70 days.
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In: Recent Advances in Small Animal Reproduction, Concannon P.W., England E.and
Verstegen J. (Eds.)
Publisher: International Veterinary Information Service (
Canine Pregnancy: Predicting Parturition and Timing Events of Gestation
(9 May 2000)
P.W. Concannon
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York,
Many aspects of canine pregnancy are unique among veterinary domestic species. Therefore, an understanding
of the time course and clinical correlates of ovulation, fertilization, embryo and fetal development, and
pregnancy specific changes in maternal physiology is essential when providing clinical services such as
breeding management and monitoring of pregnancy [1-4]. It is also important for decision-making in cases of
pregnancy failure, elective caesarian section and dystocia. One important fact is that gestation length and
events of gestation are very repeatable and predicable when viewed in relation to the time of ovulation or the
preceding the luteinizing hormone (LH) surge (Table 1 and 2). That is true, despite the fact that the normal
interval from breeding to whelping can range from 55 to 70 days.
Fertilization and Gestation Length
The reason why gestation length in dogs is relatively consistent when measured from the day of ovulation but
highly variable when measured from the day of breeding is partly understood. In the vast majority of bitches
parturition occurs 64, 65 or 66 days after the ovulatory surge in LH [1]. The latter represents the acute release
of LH from the pituitary in late proestrus or early estrus. The LH surge triggers the event of ovulation. Since
the day of the LH surge can be measured or estimated with reasonable accuracy, timing events from that day,
and using it as the reference point (Day 0) can be helpful. A 64 - 66 day gestation length measured from the
LH surge to parturition is the same as a 62, 63 or 64 day interval between ovulation and parturition, since
ovulation has been estimated to occur 2 days after the surge in LH [4].
In contrast, using the day of mating as a reference point, as observed in cases of just a single mating or
insemination, parturition can occur as early as 56 days later and as late as 68 days later. Similarly, a large
variation in apparent gestation length can be encountered when counting from the first of multiple matings or
the last of multiple matings, the extremes encountered differing by 2 weeks. For instance, if a bitch is held for
an aggressive stud dog and forced to mate starting 3 - 5 days before the LH surge, the interval from first
mating to whelping may be as long as 69 - 70 days. And, in rare instances where a bitch is still fertile 9 or 10
days after the LH surge and is bred then, the interval from mating to whelping can be as short as 55 or 56
Part of the explanation is that dog sperm may, in some instances, survive in the bitch's tract for up to 7 or even
9 days and still remain viable in terms of being able to achieve fertilization and result in pregnancy. It is
possible that in dogs as in other species, many sperm die or loose fertility after 1 or 2 days. However, the
number that retain fertility for 2 days is sufficiently high in dogs that fertility and fecundity are not affected by
matings on the day of the LH surge, 2 days before ovulation. Thus, in such pregnancies, the sperm survived 2
days before potentially penetrating the oocyte, and the chromatin had to survive another 2 to 3 days to
function as a male pronucleus which fuses with the female pronucleus to form the 1-cell zygote. Fertility
declines with matings earlier than the day of the LH surge (i.e. mating 3 or more days before ovulation).
However, litters have occasionally been obtained from forced matings, matings by aggressive males, and
artificial inseminations of fresh semen as early as 3 - 5 days before the LH surge. Sperm deposition in such
cases was 5 to 7 days before ovulation and at least 7 to 9 days before oocyte maturation. Another part of the
explanation for the large variation encountered in apparent gestation lengths lies with the timing of egg
maturation in this species. In dogs (and foxes), unlike most other species, the eggs are still immature when
they are ovulated (i.e., they are still primary oocytes) and they do not complete meiosis and become secondary
(mature) oocytes until probably 2.5 to 3 days after ovulation. An egg must be a mature, secondary oocyte
containing a "female" pronucleus before the "male" pronucleus of a sperm can fuse with it to complete the
process of fertilization by forming the nucleus of the new one-cell embryo. In early-mated bitches, a sperm
probably penetrates each egg shortly after it is ovulated, but the male pronucleus once formed has to wait for
the egg to mature. In late-bred bitches, the female pronucleus of the matured egg is ready to fuse with the
pronucleus of a sperm that subsequently penetrates as soon as the male-pronucleus is formed.
The interval of nearly 3 days required for oocyte maturation after ovulation has been estimated in at least two
ways. One is based on estimating how long after ovulation that matings from different males can still result in
pups with different sires. Another is estimation of the time after ovulation at which mating with short-lived
frozen-thawed sperm results in pregnancies. Because of this phenomenon of "delayed" oocyte maturation,
bitches can readily give birth to litters with multiple sires when there are matings by different males before
Timing of Fertilization, Fertility and Fecundity
Thus, it appears that fertilization to the point of nuclear fusion can be accomplished no earlier than about 3
days after ovulation (and, thus, 5 days after the LH surge). Following maturation of the egg to
secondary-oocyte status, the fertile life span of an unfertilized egg may be only 1 or 2 days in some instances,
since fertility declines if matings are delayed until 4 and 5 days after ovulation (i.e., 6 and 7 days after the LH
surge). That is, both litter size and pregnancy rate decline when mating occurs more than 2 days after the
maturation of the oocyte. Thus, with a narrow 2-day window for optimal fertilization to occur, it is reasonable
that gestation length is consistent when measured relative to the day of the LH surge, or to the day of
ovulation. However, some bitches may have one or more fertile oocytes survive to as late as 7 or even 8 days
after ovulation which corresponds to 9 or 10 days after the LH surge. While fertility is typically low with
matings this late, when pregnancy does occur the gestation length is usually the same that as in other bitches,
i.e., with parturition occurring at 64 - 66 days after the LH surge (and 62 - 64 days after ovulation). The above
scenario is the basis of well documented cases of bitches with exceptionally short apparent gestation lengths,
giving birth to litters as "early" as 55 to 56 days after breeding. Why true gestation length is not always
obviously longer in these "late-bred" bitches is not clear, but there are two likely reasons. First, there is as yet
unpublished evidence that eggs fertilized 2 days after maturation divide slightly faster than eggs penetrated by
sperm before maturation. (Tsutsui, 1999, personal communication) Second, it is likely that the timing of
implantation is in part related to a sequence of events regulated by the timing of the changes in serum
concentrations of estrogen and progesterone. These do not differ with the time of mating or fertilization or
early embryo cleavage rate. It is likely then that there is a very narrow window of time in whh the uterus is
receptive for implantation. Implantation is estimated to occur at Day 22 - 23 after the LH surge [6]. In some
instances of a very late mating, there are anecdotal reports that, because of the resulting small litter size, the
fetal signal for parturition is weak, and parturition may be delayed for 1 - 2 days, with an apparent increase in
gestation length. However, documented evidence for this has not been published.
It is clinically useful to consider that gestation length in bitches is in most cases 64 - 66 days, when measured
as the interval from LH surge to parturition. However, it is important to realize that intervals of 63 and 67 days
have been seen in some normal, uncomplicated pregnancies and should not be considered out of the ordinary.
Furthermore, there can be error of up to 1 days in estimating the day of the LH surge. Nevertheless, estimating
the day of whelping as 65 days after the estimated day of the LH surge can be helpful to dog owners and aid in
scheduling whelping management services. Timing the major event of pregnancy from the estimated day of
the LH surge can also aid in pregnancy testing and pregnancy management services (Tables 1 and 2).
Table 1. Events and clinical correlates of canine pregnancy through the time of implantation
and pregnancy detection, aligned to days from pre ovulatory LH surge.
Days Events and changes in parameters
-25 to -3 Onset of proestrus (heat) - average Day -9
-3 to + 6 Onset of estrus behavior - average Day 0 to 1
-3 to +8 First acceptance of intromission and mating - average Day 1
-3 First day a single mating has significant fertility
0Pre ovulatory LH surge - time of major increase in serum LH
0Increase in progesterone from levels of 0.3 - 08 ng to levels of 0.9 to 3.0 ng/ml
0Onset of peak fertility for single matings by high-fertility studs
2Ovulation at 38 - 58 h after LH surge
3Primary oocyte(s) in oviduct. Potential penetration by sperm
4Oocytes presumably still without polar body or female pronucleus
5Maturation of oocytes in distal oviduct.. Fertilization completed if already bred
6Bred: 1-2 cell embryo. Non-bred: mature oocytes still fertile
7Bred: 2 cell embryo. Non-bred: viability of some oocytes declines or lost
8Bred: 4 cell embryo. Non-bred: late mating results in small or no litter
9Bred early: 4-8 cell embryo. Bred later: 4-8 cell embryo. Mating rarely fertile
10 Oviductal embryos: 8-16 cells
11 Oviductal embryos: 16 -32 cell morulae
12 Morulae inside zona pellucida found in uterine horns
13 Intra-uterine migration of blastocysts between horns
14 Migration within uterus continues
15 Ultrasound (U/S) does not detect any difference due to pregnancy
16 Enlargement of embryos and thinning of zona pellucida
17 Blastocyst enlargement continues. Migration stops
18 Zona enclosed blastocyst in > 1 mm diameter uterine vesicle. U/S detectable
19 Uterine vesicle visible on U/S. Embryo + zona pellucida. Mucoid coat
20 Embryo expansion in >2 mm x 3-6 mm uterine vesicle. Zona absent. Thin coat
21 Blastocysts touch, but are still unattached to, endometrium. Cannot be flushed
22 Uterine swellings grossly visible by d 21-23. Embryo attached. Invasion begins
23 Placental trophectoderm invasion of endometrium continues. U/S detects embryo.
24 Heart beats may be visible on U/S. Palpable 1 cm uterine swellings
25 U/S detection of heart beat
26 Rises in serum relaxin and acute phase proteins (fibrinogen) in some bitches
28 U/S detects zonary placental mass. Relaxin typically detectable
Table 2. Events and clinical correlates of canine pregnancy from implantation to parturition,
aligned to days from pre ovulatory LH surge.
Days Events and changes in parameters
22 Uterine swellings grossly visible by d 21-23. Embryo attached. Invasion begins
23 Placental trophectoderm invasion of endometrium continues. U/S detects embryo
24 Heart beats may be visible on U/S. Palpable 1 cm uterine swellings
25 U/S detection of heart beat with high-resolution equipment
26 Rises in serum relaxin and acute phase proteins (fibrinogen) in some bitches
28 U/S detects zonary placental mass. Relaxin typically detectable. Heart beats clear
30 Palpable, distinct 3 cm uterine swellings. Easy palpation. Prolactin increases
32 Increased prolactin levels detectable
34 Maternal anemia typically evident
36 Palpation yields less-distinct uterine masses. U/S detection of fetal limb buds
38 Embryo still shorter than placental girdle
42 Embryo starts to become longer than placental girdle
46 X-ray first detects skull and spine. Obvious increase in mammary development
50 Acute phase protein levels near peak
54 X-ray may detect limbs and pelvis
56 Teeth still not visible on X-ray
58 X-ray readily detects limbs and pelvis; possibly teeth
60 X-ray readily detects teeth by now or next day. Progesterone above 3 ng/ml
62 Progesterone begins to decline. Nesting, restlessness begins over next 2-4 days
63 Early parturition / short gestation, but not abnormal
64 Early parturition / normal gestation. Progesterone below 2 ng/ml 12-24 h pre-partum
65 Mean parturition date. Predicted whelping date
66 Late parturition / normal range
67 Very late parturition, but not abnormal absent signs of dystocia
68 Over-due if normal signs of nesting and whelping are absent
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 nornocyctic anemia evident by Day 30 or 35, and maximal (with
PCV 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
re-partum behavior of nesting, digging, social withdrawal, defensiveness, and, also a corresponding drop in
rectal temperature of 1oC ; pre-partum and peri-partum discharge of normal green lochia; delivery (whelping)
of pup(s) with an average litter taking 4 to 24 h.
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 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
(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 progesterone
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 be predicted to be 65 + 1 days after the
estimated day of the preovulatory surge in LH with a reasonable degree of accuracy is effort has been placed
on accurate estimation of the day of the LH surge. The timing of other events are also predictable (Tables 1
and 2).
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
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 a 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 delectable
before Day 23 and are likely to be delectable 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 [3].
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All rights reserved. This document is available on-line at Document No. A1202.0500 .
... In addition, to evaluate whether leptin signalling is involved in embryo-maternal communication in the uterus during early pregnancy, uterine Ob and ObR mRNA concentration was compared between non-pregnant dogs in early diestrus (E-) and dogs in the pre-implantation period (E+). CL, utero-placental and inter-placental (including the pre-implantation stage) uterine sections were obtained from healthy bitches (2-8 years, different breeds) which were mated 2 days after ovulation and ovariohysterectomized at pre-implantation (days 8-12 after mating), post-implantation (days [18][19][20][21][22][23][24][25], mid-gestation (days [35][36][37][38][39][40] and at prepartum luteolysis. Dogs in early diestrus were matched to the pre-implantation group based on ovulation timing. ...
... Normal gestation length calculated from the first day of mating until birth ranges from 57 to 72 days with an average of 63 days. If the time of the LH peak or ovulation is known, parturition date can be assessed more accurately: normal duration of pregnancy is 64 to 66 days if calculated from the preovulatory surge in LH (which is simultaneous with the initial rise of progesterone), or 62-64 days if calculated from ovulation, since ovulation has been estimated to happen 2 days after the LH peak [18,19]. ...
Leptin (Ob) was originally thought to be secreted exclusively by fat tissue regulating energy metabolism and satiety. Nowadays, it is known to be produced by many organs and to influence reproductive processes as well as other bodily functions. In the dog, little is known about Ob’s role in reproduction. To investigate the potential involvement of Ob in canine pregnancy, we determined the localization of Ob and its receptor (ObR) by in situ hybridization (ISH) and immunohistochemistry (IHC) in the corpus luteum (CL), uterus and placenta of pregnant bitches and followed the changes in their gene expression levels by RT- PCR. Tissues were obtained from bitches ovariohysterectomized during pre- and post- implantation, mid-gestation and prepartum luteolysis. Also, uteri were collected from early pregnant dogs and their matched non-pregnant controls in diestrus. Ob and ObR mRNA and protein were detected during all stages of pregnancy in various cell types of the CL, uterus and placenta. ObR mRNA expression was increased in the pre-implantation uterus and in inter-placental sections at post-implantation. At placentation sites Ob mRNA was highest during post-implantation and prepartum luteolysis, and ObR expression was up-regulated prepartum. In the non-pregnant diestrus uterus Ob mRNA was below the detection limit, and ObR was not different between the groups. In conclusion, Ob may be involved in the establishment and maintenance of canine pregnancy in a paracrine/autocrine mann.
... Bij deze honden wordt het tijdstip van levensvatbaarheid van de foeti bij voorkeur bepaald aan de hand van de progesteronwaarden verkregen tijdens de cyclusopvolging. Zo kan de keizersnede veilig worden uitgevoerd vanaf 62 tot 63 dagen na de LH-piek, of 60 tot 61 dagen na de ovulatie (Concannon, 2000). ...
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Het optimale tijdstip bepalen voor de keizersnede bij de hond kan een uitdaging betekenen voor de praktijkdierenarts. Er moet rekening gehouden worden met de berekende partusdatum, het al dan niet op gang zijn van de partus en het al dan niet aanwezig zijn van dystocie. Sommige teven hebben een verlengde dracht, bij andere start de partus te vroeg. In beide gevallen is de kans op overleving van de pups zeer laag. Ook wanneer er bij dystocie te lang gewacht wordt om een keizersnede uit te voeren, komt de overleving van de pups in het gedrang. Het is daarom van groot belang de juiste partusdatum bij elke individuele hond te kunnen voorspellen, zeker bij risicopatiënten. De partusdatum kan berekend worden door het begin van de metoestrus te bepalen via vaginale cytologie of door embryonale en foetale structuren te meten via echografie. De meest accurate methode is echter door middel van cyclusopvolging met progesteronmeting.
... In a questionnaire-based evaluation of pre partum behaviour in the bitch, owners described changes in behaviour in approximately 50% of the bitches with at least one of: lack of attention, drowsiness, aggression, anxiety, fickleness, capriciousness, irritation, increase in attention requests and a change of appetite (Ferrari & Monteiro-Filho 2004). Prewhelping behaviours, as described above, have been attributed to the sharp decline in blood progesterone during the 24-hour pre partum period (Concannon 2000). However, the isolation commonly observed in wild canids (Kleiman 1968, AZA Canid Taxon 2012) is not always observed in the domestic dog. ...
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Here we review information on maternal behaviour in dogs, defined as a combination of all the acts of the mother towards her offspring, which begins before parturition and continues until weaning. In dogs, maternal care is measured using the most commonly observed behaviours, such as the time spent in contact, licking/grooming and nursing of the puppies. Since newborn puppies have a very limited capacity for movement, maternal interaction is essential to their survival, nourishment and protection. It is also an important element of the bonding process between puppies and the bitch and is thought to play a role in the social development of the puppies. Nevertheless, some questions still need to be clarified, such as the best way to quantify factors that may interfere with maternal behaviour. In recent studies, maternal care, or maternal style, was measured using a scoring system and found to be influenced by factors such as litter size, breed and parity, or even human interaction. However, the impact of the emotional state of the bitch and the quality of maternal behaviour on puppy survival and development remain unclear. The long-lasting effects of mother-puppy interactions on puppy behaviour during their adult life are still poorly understood, despite their importance for breeders who wish to prevent future problem behaviours.
... The main diagnostic techniques for the monitoring of heat are physical and laboratory examinations. Vaginal cytology facilitates the determination of the cycle but it remains insufficient in the precision of the moment of ovulation and requires to be combined with the ultrasound and hormonal analyzes which are the methods of choice for the diagnosis of estrous cycle disorder in bitch [2,3]. The echography of the ovaries has the advantage of directly visualizing the ovaries and the uterus without being invasive with the proportioning of progesterone it makes it possible to diagnose ovulation with precision and to even detect anomalies of ovulation [4,5]. ...
Eight atlas shepherd bitch tow years old and weighing between 14 and 16 kg have received a heat induction treatment with bromocriptine (Parlodel® 2.5 mg Breakable tablet Box of 30 tablets). The dosage adapted for the dog was 1.25 mg/15 kg body weight per day for a heat induction. The heats were followed from the 5th day of proestrus and during estrus to the canine clinical pathology of veterinary institute Ibn Khaldoun University of Tiaret between January 2014 and January 2015. For the diagnosis of ovulation the vaginal smears and ultrasound of the ovaries were combined with the proportioning of progesterone. No structural anomaly of ovaries and no genital infection were observed on clinical examination. The aim of this study is: To answer the question: Can Bromocriptine treatment induce ovulatory heat? All bitches (8/8) showed vulvar loss between day 21 and day 40 of Bromocriptine treatment. 89% (7/8) bitches exhibited a significant positive chronological evolution between the progesterone blood level and eosinophilic index and diameter of ovaries in. The ovarian diameter in 100% (8/8) bitches was 19 +/- 2.07 mm at the moment of ovulation.
... Gestation length ranges from 62 to 64 days (63 ± 2 days) between ovulation and delivery, and ovulation typically occurs 48-60 h after the LH peak (Concannon 2000;Concannon 2011). In the present study, when the day of the first mating was regarded as the first day of pregnancy, the Yorkshire terrier females whelped between 55 and 71 days after mating and the mean gestation length was 62.57 ± 2.524 days. ...
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The aim of this study was to determine the basic reproductive parameters, i.e., litter size, gestation length, neonatal mortality rate and the type of delivery in Yorkshire terrier dogs, one of the most popular breeds in Poland. We have verified a hypothesis put forward by breeders that larger females have fewer whelping difficulties and produce larger litters and that pregnancies of females having one or two pups last longer. The focus of investigation was reproductive data from 66 Yorkshire terrier females registered in the Lublin Branch of the Polish Kennel Club, an FCI (Federation Cynologique Internationale) member, which whelped 124 litters comprising in total 508 pups from 37 fathers. The data were collected between August 2009 and December 2014. The significance of differences was verified using Mann-Whitney U and Kruskal-Wallis H-tests. The relationships between the recorded dogs’ reproduction traits were estimated by calculation of Spearman’s correlation coefficients with the use of the statistical programmes Statistica and SPSS 20. The investigations have confirmed the hypothesis concerning the larger litter size produced by larger females and the lower incidence of postpartum dystocia; however, the hypothesis of the impact of body weight on the length of pregnancy was rejected. The differences between the body weights of stud females and males reached 125%. The Yorkshire terrier appears to be a good reproductive breed with normal reproductive functions and good reproductive parameters.
Add "in dogs and cats"? This article covers image acquisition of the fetus and the reproductive organs of the female (cervix, gravid and nongravid uterus, and ovaries) and male (testicles and prostate) reproductive tracts. This article is a brief overview of normal sonographic anatomy and important clinical conditions for each sex using point-of-care ultrasound as a screening test. In addition to normal sonographic appearance and common conditions of the scrotum and testes, prostate, uterus, and ovaries, this article discusses the use of ultrasound for diagnosis of and evaluating pregnancy, fetal maturation, and fetal stress during dystocia.
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In dogs, the phase from mating to the end of weaning lasts about 120 days and encompasses many aspects that, interacting, contribute to increase the allostatic load. The coat and claws, useful for long-term change assessments, have the advantage of being collectable without invasiveness. In the present study, the Cortisol (C) and Dehydroepiandrosterone-sulfate (DHEA-S) concentration monthly changes in the coat and claws were studied in female dogs from mating to the end of weaning to assess Hypothalamic–Pituitary–Adrenal (HPA) axis activation during pregnancy and the post-partum period. The results from 15 Dobermann Pinscher female dogs showed a trend of increase of the coat C from mating to 60 days post-partum, with significant changes between mating and parturition-60 days post-partum (p < 0.01) and between the 30-day pregnancy diagnosis (PD) and 30–60 days post-partum (p < 0.05). The claws C trend showed significant increases between mating and 30–60 days post-partum (p < 0.05) and between the PD and 60 days post-partum (p < 0.01). DHEA-S in both matrices showed non-significant changes. The results suggest that maternity could play a pivotal role in the HPA axis activation, with a subsequent chronic secretion of C determining an increase in the allostatic load in the mothers. Neither maternal parity nor litter size played a significant role in the accumulation of C and DHEA-S in both matrices.
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Immune system recognize and fight back foreign microorganisms and inner modifications that lead to deficient cell and tissue functions. During a dog’s life, the immune system needs to adapt to different physiological conditions, assuring surveillance and protection in a careful and controlled way. Pregnancy alters normal homeostasis, requiring a balance between immunity and tolerance. The embryos and fetus should be protected from infections, while the female dog must tolerate the growing of semi-allografts in her uterus. After birth, newborn puppies are at great risk of developing infectious diseases, because their immune system is in development and immune memory is absent. Passive transfer of immunity through colostrum is fundamental for puppy survival in the first weeks of life, but hampers the development of an active immune response to vaccination. At the end of life, dogs experience a decline in the structure and functional competence of the immune system, compromising the immune responses to novel antigenic challenges, such as infections and vaccines. Therefore, the current article reviews the general processes related to the development of the dog´s immune system, providing an overview of immune activity throughout the dog’s life and its implications in canine health, and highlighting priority research goals.
Dystocia is a common true emergency. An understanding of normal parturition and the physiology that underlies it is critical to managing dystocia effectively. Previous systems for classifying dystocia in small animals have been extrapolated from large animal practice. A new method for classifying small animal dystocia is proposed here. Clinical history, physical examination, and relevant diagnostics will identify a patient with dystocia, and determine whether medical or surgical intervention is warranted. It is critical that a clinician understand when medical management may be attempted, and when surgical intervention is necessary.
Characterization of proteins secreted by the endometrium and the conceptus, and timing of the secretion relative to endocrine patterns, ovulation and implantation is essential for understanding mechanisms in maternal recognition of pregnancy. Plasma estradiol-17β, progesterone and serum LH were assayed in samples taken daily during proestrus, estrus and diestrus in 8 adult bitches. The day of the LH peak (DL 1) was accepted as the first day on which LH concentrations exceeded the preceding day's value by 2 SD. Embryos were flushed from uteri collected on DL 16 to 20, and incubated with (35S) methionine in MEM; nascent polypeptides in the medium were characterized by 2-dimensional SDS-PAGE. Some attached embryos were first observed on DL 20, and all embryos were attached on DL 22. Major radiolabeled proteins recognized on fluorograms were canine protein 1 (cP1) (Mr = 86,000, pI 5), cP2 (Mr = 42–44,000, pI 5.5−5), cP4 (Mr = 30−28,000, pI 5), cP6 (Mr = 20–25,000 pI 5.5minus;5) and the canine conceptus protein 7 (cCP7) (Mr = 18,000, pI 4). All the proteins were found in samples taken from DL 19 to 20. Proteins cP1 through cP6 were identified as produced by the embryos in this study. They were found to migrate on 2D-SDS-PAGE in a manner judged to be identical to proteins that had been produced by the endometrium. Canine Conceptus Protein 7 was found to be secreted prior to implantation, only by blastocysts.
Serial ultrasonographic examinations were performed on 8 Beagle bitches from 20 to 60 days pregnant to determine time of first detection, appearance, and sizes of selected features of pregnancy. Gestation was timed from the day of the preovulatory luteinizing hormone surge. Findings related to gestational age were consistent among bitches. Gestational ages at earliest detection of the following features were: chorionic cavity at day 20; placental layers in the uterine wall at day 22 to 24; zonary placenta at day 27 to 30; embryo and heartbeat at day 23 to 25; yolk sac membrane at day 25 to 28; allantoic membrane at day 27 to 31; choroid plexus of the brain at day 31 to 35; fetal movement at day 34 to 36; skeleton at day 33 to 39; bladder and stomach at day 35 to 39; kidney at day 39 to 47; and liver hypoechoic, compared with lung, at day 38 to 42. Extra-fetal structures were measurable from day 20 or 22 through day 48. Chorionic cavity diameter increased from 0.2 +/- 0.0 cm to 3.3 +/- 0.2 cm, outer uterine diameter increased from 0.8 +/- 0.03 cm to 4.8 +/- 0.2 cm, length of chorionic cavity or zonary placenta increased from 0.3 +/- 0.03 cm to 4.9 +/- 0.05 cm, uterine wall thickness increased from 0.3 +/- 0.03 cm to 0.8 +/- 0.01 cm, and placental thickness increased from 0.1 +/- 0.0 cm to 0.5 +/- 0.05 cm. Chorionic cavity diameter, outer uterine diameter, and placental length each increased at a linear rate through day 37, after which time, each had a marked plateau in growth. Of the extra-fetal structures, chorionic cavity diameter was the most accurate for estimation of gestational age. All of the fetal structures studied increased at an increasing (second order) rate. Crown-rump length increased from 0.3 +/- 0.05 cm on day 24 to 9.2 +/- 0.2 cm on day 48. Body diameter increased from 0.2 +/- 0.03 cm on day 24 to 4.6 +/- 0.15 cm on day 60. Head diameter increased from 0.8 +/- 0.05 cm on day 34 to 2.7 +/- 0.04 cm on day 60. Of the fetal structures, head diameter was the most accurate for estimation of gestational age.
There is considerable variation among bitches in commonly encountered intervals between cycles (5-12 months), durations of anoestrus (1-8 months), durations of follicular phase pro-oestrus (3-21 days) and periovulatory oestrous behavior (3-21 days), intervals from preovulatory LH surge to oestrus onset (-2 to 5 days), and intervals from fertile mating to parturition (57-68 days). The extent of variation within bitches ranges from slight to great. However, there appears to be very little variation in the intervals from LH surge to ovulation (2 days), to post-ovulatory oocyte maturation (approximately 4 days), to implantation (approximately 18 days), to selected developmental stages of pregnancy, or to parturition (64-66 days). There are no tests diagnostic of early pregnancy. The onset times of persistent pregnancy-specific changes have been estimated, including radio-opaque fetal details (Day 46), elevated blood prolactin values (Day 35), elevated blood relaxin values (Day 25), echogenic heart beats (Day 24) and embryonic vesicles (Day 19), and potentially palpable uterine enlargements (Day 21). As in humans, there is an anaemia of pregnancy involving a 30% reduction in haematocrit and an increased incidence of insulin resistance during the second half of gestation. Ovarian progesterone is required throughout pregnancy. LH and prolactin are luteotrophic in the pregnant bitch as well as during the 2-month luteal phase of the non-pregnant bitch. Parturition follows a luteolysis which occurs during an increase in prostaglandin F-2 alpha that begins 36 h pre partum. Factors regulating the duration of anoestrus are not known but termination of anoestrus is associated with increased pulsatile secretion of LH.
The onset and progression of canine fetal skeletal radiopacity were studied in relation to the times of mating, the preovulatory peak in serum luteinizing hormone (LH) levels, and parturition for each of 6 pregnancies. Lateral radiographs were obtained at 2- to 3-day intervals 30 days after mating and at 1- to 2-day intervals during the period fetal skeletons became radiopaque. Radiographs were assessed as to whether fetal elements were absent, barely discernible, distinct, or obvious. Fetal skeletal elements were 1st detected 20 to 21 days before parturition (42 to 52 days after mating and 44 to 47 days after the LH peak). Radiographs of fetal skeletons, sufficiently distinct for an unequivocal diagnosis of pregnancy, were obtained 17 to 20 days before parturition (43 to 54 days after mating and 46 to 49 days after the LH peak).
To describe dogs undergoing cesarean section in the United States and Canada, to determine perioperative management, and to calculate survival proportions. Multicenter prospective case series. 3,908 puppies from 808 dams. Survival rates immediately, 2 hours, and 7 days after delivery were 92, 87, and 80%, respectively, for puppies delivered by cesarean section (n = 3,410) and 86, 83, and 75%, respectively, for puppies born naturally (498). For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born alive. Maternal mortality rate was 1% (n = 9). Of 776 surgeries, 453 (58%) were done on an emergency basis. The most common breeds of dogs that underwent emergency surgery were Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua. The most common breeds of dogs that underwent elective surgery were Bulldog, Labrador Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier. The most common methods of inducing and maintaining anesthesia were administration of isoflurane for induction and maintenance (n = 266; 34%) and administration of propofol for induction followed by administration of isoflurane for maintenance (237; 30%). Mortality rates of dams and puppies undergoing cesarean section in the United States and Canada are low. Knowledge of mortality rates should be useful to veterinarians when advising clients on the likelihood of puppy and dam survival associated with cesarean section.
The size of the gestational sac and embryonic mass as well as the embryonic heartbeat were examined ultrasonographically from Day 16 to 25 of pregnancy in 15 beagle bitches, using a 7.5 MHz transducer. Results were more consistent when gestational age was based on the day of the preovulatory luteinizing hormone (LH) surge than on the day of first breeding. The gestational sac was first detected at 17 to 20 d after the LH surge, when it was 1 to 2 mm in diameter and 1 to 4 mm in length. The diameter and length of the gestational sac increased exponentially. At Day 25, the mean diameter was 8.2 +/- 0.3 mm (7 to 9 mm) and mean length was 20.3 +/- 1.1 mm (14 to 24 mm). Embryonic mass and heartbeat were first detected at 23 to 25 d after the LH surge. The embryonic heartbeat was detected on the day of or the day after detection of the embryonic mass, at which time the embryonic mass was 1 to 4 mm in length and was located at the periphery of the gestational sac.
Pregnancy in Dogs and Cats
  • P Concannon
  • J Verstegen
Concannon P and Verstegen J. Pregnancy in Dogs and Cats. In: Knobil E and Neil JN, eds. Encyclopedia of Reproduction, Vol. 3. New York: Academic Press, 1998. -Amazon
Hormonal and clinical correlates of ovarian cycles, ovulation, pseudopregnancy and pregnancy in dogs
  • P W Concannon
  • D H Lein
Concannon PW and Lein DH. Hormonal and clinical correlates of ovarian cycles, ovulation, pseudopregnancy and pregnancy in dogs. In: Kirk RW, ed. Current Veterinary Therapy, Small Animal Practice, Vol. X. Philadelphia:W. B. Saunders, 1989: 1269-1282.
  • A E Yeager
  • P W Concannon
Yeager AE and Concannon PW. Ovaries. Uterus. In: Green RW, ed. Small Animal Ultrasound. Philadelphia: Lippincott Williams & Wilkins, 1995; 293-303. -Amazon -
Pregnancy in Dogs and Cats
  • Concannon P Verstegen
Concannon P and Verstegen J. Pregnancy in Dogs and Cats. In: Knobil E and Neil JN, eds. Encyclopedia of Reproduction, Vol. 3. New York: Academic Press, 1998. -Amazon -