Pregnancy in a dog: duration, recognition, stages by week

PALPATION OR ULTRASONIC DIAGNOSTICS

Diagnosis of pregnancy in bitches is carried out mainly by palpation. This is an easy and inexpensive method. Currently, ultrasound diagnostics has become more accessible for practical use; it is an excellent way to identify and confirm pregnancy. Using ultrasound, you can easily diagnose pregnancy already on the 20-25th day. On the 45th day of pregnancy, radiography can also be used to count the number of fetal skeletons, estimate their size, visualize symptoms of fetal death, and monitor the position of the fetuses.

Calculation of the duration of pregnancy in bitches depends on the event that is the starting point. Counting from the date of the first mating? Normal pregnancy can last from 57 to 72 days. These variations may be influenced by the period between mating and ovulation, sperm viability (6 to 7 days), time of oocyte maturation (2-3 days after ovulation) and the actual time of opening of the oviduct-uterus junction (approximately 10 days after ejection). LH), as well as the time of passage of blastocysts into the uterus. Successful fertilization can be achieved 5 days before and 7 days after ovulation.

CALCULATION OF PREGNANCY DURATION

Various methods are used to accurately calculate the duration of pregnancy. The most common method is based on determining the day of the preovulatory peak serum LH concentration, which is observed 48 hours before ovulation. It was agreed that the day of the LH peak is considered day 0, and the days of the cycle and the days of pregnancy are counted from this event. In principle, there will be little difference in the length of pregnancy if you count from day 0 or from the day of ovulation. Thus, the duration of pregnancy is counted from day 0, it will be 65 +/- 1 day after the LH peak. Determination of the peak concentration of LH is not carried out in all laboratories. Knowing about preovulatory luteinization of follicles, the LH surge can be determined by the increase in plasma progesterone concentration, which will coincide with the LH peak. In this article, the number of days of pregnancy is counted from day 0, which coincides with the LH peak.

If the day of the LH peak is not determined by the increase in progesterone concentration, then a cytological assessment of vaginal smears can be used as a fallback option. In this case, the starting point will be the onset of diestrus (day 1 of diestrus), when the number of surface epithelial cells decreases to 50% or below. The 1st day of diestrus coincides with the 8th day of pregnancy or the 8th day of the cycle (7th, 8th or 9th day of the cycle in healthy bitches). If you count from the 1st day of diestrus, then approximately 80% of bitches whelp on the 57th day +/- 3 days.

The diagnosis of pregnancy should not be based on secondary symptoms (nesting behavior and anorexia), because they can also be observed in bitches with false pregnancies.

Sixth to seventh week: pregnancy is obvious

In the period from the 36th to the 43rd day, the development of embryos accelerates. Primary sexual characteristics appear, shoulder blades and fingers are formed and hair grows. The size of future cubs reaches 6.5 centimeters. On the 44th day, the dog’s uterus enlarges and occupies most of the abdominal cavity. Puppies can already be felt by palpation, but it is difficult to determine their exact number.

It is recommended to increase the amount of food by 20%, offer portions more often, but make them even smaller. This is good for pregnant dogs. You can schedule your diet by day and time to simplify your task and not rack your brains about how to feed your pet. On the 47th day, the expectant mother begins to look for shelter for childbirth and spends most of her time licking her nipples. It's time to make an enclosure or equip part of the room and gradually accustom the dog to this place.

PALPATION

Migration of blastocysts between the horns of the uterus is observed on the 12-16th day. The sites of their implantation are determined on the 18-19th day (Yeageretal., 1992). Implantation occurs on the 20th day (Thatcher et al., 1994). On the 22-24th day of pregnancy (14-16th day of diestrus) or on the 20-26th day after the last mating, individual chorioallantoic ovoid extensions (1-2 cm in size) are easily palpated on the placental places along the uterine horns, especially in distal caudal position (Whitney, 1936). At this stage, the uterus is dense, so its body is first palpated (between the bladder and rectum, cranial to the vagina and cervix), and then cranial at a distance between the doctor’s thumb and index finger. A distinction should be made between a palpable pregnant uterus and a colon filled with feces.

Enlargements in the uterine horns are easily palpable only on the 10-15th day (20-35th day). As a rule, the diagnosis of pregnancy is carried out on the 26-28th day after the first mating, if the concentration of progesterone and the results of vaginal cytology are not known. If no pregnancy symptoms are detected at the first palpation, a second assessment is made a week later. In small litters, fertilized eggs occupy an extreme cranial position under the ribs, but they can also be identified by palpation. In medium-sized dogs, dilatations in the uterine horns reach 3-5 cm at day 28, so they are easiest to identify at this stage. After the 30th day of pregnancy, the uterus begins to rapidly enlarge and takes a more cranioventral position; at this stage, individual expansions are most difficult to palpate.

PALPATION AND HORNS OF THE UTERUS

The uterine horns descend to the ventral wall, and the anterior part of the horns passes cranially under the ribs, which makes palpation difficult. On the 35th day, the dilations become oblong and soft, they practically merge with each other, which makes it difficult to palpate them as separate bodies, and diffuse stretching of the uterus makes palpation completely meaningless. After 45-50 days it is easy to identify individual fruits. The results of palpation can be influenced by the temperament, body condition and size of the bitch, as well as the number of fetuses. False positive results can be caused by pyometra, especially in the form of sacs that look like fruit.

Other symptoms, such as breast enlargement, are not an indicator of pregnancy because they can also occur in false pregnancies. Apparent false pregnancies are observed in some bitches in late diestrus due to a sudden and premature drop in progesterone concentrations, which causes a rise in noolactin concentrations, just as occurs in pregnant bitches before giving birth (Okkensetal., 1997).

Behavioral symptoms of pregnancy

In the first month, pregnancy in dogs is still invisible, but an attentive owner will be able to determine the interesting position of his pet by behavior. Beginning breeders should note the dog’s pregnancy day by day and take detailed notes in a notebook.

In the early stages, pay attention to your pet’s appetite. Typically, pregnant bitches lose their appetite in the first month of gestation and eat less than usual. However, not all dogs lose interest in food, and this is not always an indicator of pregnancy. In the second month, appetite increases sharply again.

In the first weeks of pregnancy, your pet may notice apathy, lethargy, slowness, a desire to sleep more, and ignoring the owner’s commands. But this can be considered an indicator of pregnancy if your dog was always energetic and playful before mating. In the early stages, your pet can become overly sociable and affectionate. However, the opposite situation also occurs when the dog seeks privacy in secluded corners.

ULTRASONIC DIAGNOSIS OF PREGNANCY IN BITCHES

Transabdominal ultrasonography is the ideal method for diagnosing pregnancy in dogs. It has already become a routine diagnostic measure to determine early pregnancy, fetal viability or fetal resortion after the 25th day of pregnancy (Fig. 1). When using ultrasound to diagnose pregnancy, the equipment used, the experience of the operator and the temperament of the bitch should be taken into account. Some bitches may need to have their belly hair shaved, which may require the owner's consent. Dogs are usually examined in a dorsal position, but some nervous dogs may need to be examined standing. The choice of equipment depends on the duration of pregnancy, the size of the bitch and obesity. To determine pregnancy, a 5 MHz sensor is most often recommended. To diagnose pregnancy before the 30th day, as well as to examine small dogs (less than 7 kg), you can use a 7.5 MHz sensor.

Embryos are easily visualized as early as day 19 or around day 11 of diestrus (Fig. 2). But this requires experience and advanced equipment. Typically, embryos are visualized on the 24th day of pregnancy or on the 16th day of diestrus (Fig. 3).

At approximately the 35th day of pregnancy, the head and body of the fetus are equal in size and appearance (Fig. 4).

The fetal heartbeat is determined on the 24-25th day, and movements - on the 34-36th day. With small litters, ultrasound can even count the number of fetuses. However, as the litter increases, counting the number of fruits becomes very difficult (Fig. 5).

BIPAREETAL DIAMETER

The stages of pregnancy can be determined by the biparietal diameter (longitudinal section in the head area, aligned with the body of the fetus) and body diameter (cross section in the stomach area) of one or more puppies (Fig. 6).

The diameters of several fetuses should be measured at once, because their sizes can differ greatly from each other. The biparietal diameter and the diameter of the body of the fetuses correlate with the gestational age. The timing of identification of different fruit structures is still under study (Yeageret et al., 1992). The time of first identification of individual fetuses in pregnant dogs is given in Table 1.

FETAL HEART RATE

The good condition of the fetuses is often determined by the heart rate. The normal heart rate is 200-255 beats per minute on the 30th day of pregnancy (Ventegenetal., 1993). Further research is needed to explain the relative decrease in heart rate (less than 200 beats per minute) due to fetal distress.

Ultrasound is an excellent tool for excluding pregnancy in non-pregnant bitches with pyometra in which “pregnancy” was determined by palpation (Fig. 7).

Why such a short gestational age?

Pregnancy of dogs by day is sixty to seventy days. This is very small and unusual for a person. However, nature has an explanation for this phenomenon.

Dogs, by their origin, belong to the class of predators. And meat-eating animals bear their offspring for a fairly short period - from two to three months. Predators follow the principle of survival in nature. It is difficult for a pregnant dog to hunt, and this can have a detrimental effect on her and her offspring. It is much easier to take out the chicks in a short time, hide them and feed them in the den.

RADIOGRAPHIC DIAGNOSIS OF PREGNANCY IN BITCHES

Most often, radiography is used to determine the size of the litter before birth. After delivery, x-rays are taken to ensure that all puppies have been born. Radiographs of non-pregnant bitches rarely show a uterus.

In pregnant bitches, uterine enlargement can be detected only on the 21st day of pregnancy. From the 21st to 42nd day of pregnancy, you can see enlarged, fluid-filled uterine horns.

The skeletons of the fetuses become radioopaque on days 44-47 of pregnancy or on days 35-40 of diestrus, and the skull and spine become visible before the long bones and finger bones. It takes 2 days to make an accurate diagnosis of pregnancy (Conson and Rendano, 1983). The teeth of the fruits are distinguished on the 58-63rd day. If we are based on the date of the first mating, then skeletal mineralization can be identified already on the 42-52nd day after mating

After the 47th day of pregnancy, when the skeletons of the fetuses are mineralized enough to become radioopaque, but X-rays can determine the size of the litter. It depends on many factors, but most often small breeds will have 2-4 puppies, medium breeds will have 4-7, and large dogs will have 6 to 10 puppies. X-rays can accurately count the size of a small litter, but even though it is more accurate than ultrasonography, it is not always possible to count the number of puppies in large litters from X-rays. The easiest way to determine litter size is by counting the number of skulls and spines on x-rays (Figures 8 and 9).

DETERMINATION OF FRUIT VITALITY

Using radiography, you can confirm the viability of the fetuses by the absence of intrauterine sacs filled with gas, or deformation and bending of parts of the skeleton, which occurs after the death of the fetuses (Fig. 10).

X-rays can also be used to determine the size of the skull to compare it with the bitch's pelvic cavity. Severely anxious owners may request abdominal x-rays to predict impending labor. However, if there are no too large fetuses (1-2 per litter), then measuring the skeletal elements of the fetuses is not very informative in predicting the difficulty of the upcoming birth. X-rays are also used to check whether there are any unborn puppies remaining after the apparent end of labor.

What happens in the second and third weeks

At the beginning of the second week, the embryos implant in the lining of the uterus, which forms into the placenta. The embryos at this stage do not even reach a millimeter in size. On the fifteenth day, a new stage of intrauterine growth begins: the vital organs of future babies develop. From this moment on, it is very important to closely monitor the dog’s condition, since everything that happens will affect the formation of embryos.

On the sixteenth or seventeenth day, the embryos grow to one millimeter. Their body, spine, head and central nervous system are formed. Between the eighteenth and twentieth days, internal organs develop. Embryos increase in size up to four millimeters.

At the end of the third week (on the 21st day), the heart is formed. The size of the embryo is already half a centimeter, but this is still not enough to see the developing kitten on an ultrasound. But it is still possible to diagnose pregnancy: the membranes of the fruit will be visible on the screen. At this stage, the owner should control the dog's appetite. Malnutrition and resulting lack of nutrients will harm future puppies.

ENDOCRINOLOGICAL AND BIOCHEMICAL DIAGNOSTICS OF PREGNANCY IN DOGS

Pregnancy-specific gonadotropins have not been observed in dogs as seen in horses or humans, and plasma progesterone concentrations will not differ greatly between pregnant and non-pregnant bitches, so they cannot be used to diagnose pregnancy.

In late iroestrus, the concentration of progesterone is less than 1 ng/ml, it reaches its peak - 15-80 ng/ml - on the 30th day, and then slowly increases to 4-5 ng/ml by the 62nd day with a sharp drop to 2 ng/ml 24-48 hours before birth. The secretion of progesterone is necessary to maintain pregnancy throughout the entire period. Pregnant bitches have slightly higher progesterone concentrations than non-pregnant bitches, but not enough to be of diagnostic value.

Relaxin is the only pregnancy-specific hormone in dogs. Serum concentrations of relaxin increase during pregnancy; in non-pregnant bitches its concentration is undetectable. In pregnant women, the serum concentration of relaxin becomes detectable at the earliest on the 28-30th day of pregnancy and reaches its peak on the 40-50th day. After childbirth, serum relaxin levels increase sharply, but may remain at detectable levels for another 50 days during lactation. There is an assumption that relaxin is mainly produced by the placenta, and in smaller quantities by the ovaries (Steinetzetai, 1989). To determine relaxin, immunoassays adapted for diagnosing pregnancy are used. However, relaxin testing is not a widely used pregnancy test.

PLASMA PROTEINS

Common pregnancy tests in North America and Europe are based on the analysis of acute-phase protein concentrations in plasma or serum. Whether these measurements include fibrinogen or C-reactive protein (CRP) is unclear, although one test (SeronoDiagnostics, United Kingdom) is based on fibrinogen measurement (Eckersalletal, 1993). Typically, the concentration of fibrinogen increases on the 25-30th day, and has a diagnostic value on the 30-50th day of pregnancy, and then decreases to its previous values ​​(Cunzel et al., 1996; Cunzel-Apeletal., 1997). In homologous analysis of CPB in dogs, the level of this protein also increases significantly on days 30-50 and reaches diagnostic values ​​(Eckersallet et al., 1993), but the test for human CPB is of limited value for diagnosing pregnancy in dogs (Colson et al., 1996). The false-positive rate is likely to be higher when acute-phase protein concentration tests are used to diagnose pregnancy in dogs because the concentration of these proteins may increase during inflammation such as pyometra. Moreover, their use depends on the correct determination of the physiological day of pregnancy. The rise in the concentration of these proteins may be due to an inflammatory-like reaction of the uterus to the process of placenta formation.

Thus, while there are no acceptable blood tests that can help diagnose pregnancy in dogs, in the future the most accurate test will be the determination of relaxin concentrations, and at present, visualization of fetal heartbeats by ultrasonography on day 25 of gestation remains the only diagnostic test for confirmation and monitoring of pregnancy

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Fourth to fifth week

During this period, you need to carefully monitor the dogs’ pregnancy day by day, since from the 22nd day you need to change the feeding regimen. Your pet may refuse food due to morning sickness, so it is best to offer food often, but in small portions. From the 23rd day, the embryo grows to a centimeter and develops eyes, nose, ears, jaw and liver. On the 25th day, the formation of teeth, limbs and spine can be observed.

On the 26th day, the embryo is already the size of a walnut, and an experienced veterinarian will be able to diagnose pregnancy by palpation of the abdomen. It is recommended to limit the dog to active games so as not to harm the fruits. From the 27th to the 31st days, “calcification” occurs in the area of ​​the skull and jaws. From the 32nd day, the future pups begin to grow rapidly, so it is worth introducing more protein into the dog’s diet.

General description of the condition and duration

In dogs, pregnancy normally lasts from 60 to 70 days. At the same time, completely viable babies can be born as early as 58 days. If childbirth occurred earlier, this is considered a pathology. Premature birth can be caused by injuries, a hidden course of the disease, a very young or old body, as well as the exhaustion of the female or her excessive obesity.

If babies were born before 72 days, this is considered normal. This is due to the fact that the duration of gestation may vary slightly among different breeds. If childbirth does not occur on the 73rd day, a consultation with a veterinarian and a caesarean section is necessary. To perform it successfully, you need to accurately determine the location of the puppies in the stomach of a pregnant dog.

It is worth noting that the first pregnancy can be unpredictable, so it is very difficult to determine when a dog is due to give birth. The timing may be affected by the following factors:

• breed of animal;
• weight;
• the number of puppies, as well as their sizes.

Small breeds of dogs usually bear offspring for 60 days. In this case, there can be 3-4 babies in a litter. In large breeds, puppies are often born on the 65th day of pregnancy. A litter here can consist of up to 15 puppies.

The more babies there are, the longer they will be born. At the same time, the development of the fetus in dogs by day almost does not depend on the breed. Therefore, owners of any breed of dog can use standard charts to track the condition of puppies in the womb. The location of the fruits does not vary much depending on the breed.

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How to tell if a dog is pregnant?

After mating, it is impossible to immediately recognize whether conception has taken place or not, since no special changes will occur. After 14 days, some females may develop a depressed mood, a decrease or complete indifference to food. This behavior is completely normal, including when the dog becomes pregnant. Starting from this period and after 30 days, the animal’s nipples swell, changing color to a bright pink hue.

However, behavior, sleep and food cravings remain unchanged. During weeks of pregnancy in dogs, the owner needs to increase the number of feedings to three feedings a day. Please note that during pregnancy, increased portions of fermented milk products and foods containing large amounts of protein should be important in the diet.

From the second month you can observe an increase in the abdomen near the ribs. 20 days before the upcoming birth, the female gains weight at a rapid pace, it is important to monitor her nutrition. When the dog is in a lying position, you can clearly see the movement of the puppies. Do not forget also about walking the dog, but without any stress, so as not to affect the development of future offspring.

Last weeks of pregnancy

From the 50th to the 57th day, the fetuses are already fully formed and grow from 12 centimeters to 15. The expectant mother mainly lies and licks herself, and movements of the puppies can be seen in the stomach. On the 58th day, if you press on the nipples, milk will appear.

On the 59-62nd day you need to be ready for labor; it can begin at any time. Stock up on necessary medications and equipment. Measure your temperature in the morning and evening. The day before birth it drops sharply.

On the 63rd day, the amniotic fluid breaks and the cervix dilates. The next day, hormonal changes occur. The uterus contracts intensely, which causes contractions. Puppies are not born in a row, but at short intervals.

Be sure to use this dog pregnancy calendar for the days your pet is pregnant. And do not leave her unattended; at any moment you may need the help of a veterinarian.

Care during pregnancy of a toy terrier

A common mistake that Toy Terrier owners make is overprotection of their pet, even to the point of constantly carrying the animal in their arms. Caring for a pregnant bitch should be the same as before mating; everything about caring for a toy terrier can be read here (Caring for a toy terrier), with the exception of some nuances.

There is no need to deprive the dog of walks, but it is necessary to carefully ensure that the bitch does not fight with other animals. It is also worth protecting the dog from drafts, hypothermia, jumping from heights, and, as the belly grows, from walking on stairs.

Due to the high risk of various complications in toy terriers, it is better to agree with a veterinarian about the management of pregnancy and delivery. After all, medical care not provided on time can cost not only the lives of puppies, but also their mothers.