Parturition has its problems too

It's not easy to foresee a problem occurring during delivery, or to recognize an anomaly at that moment. Nevertheless, most problems encountered at this stage can be easily resolved, provided you don't panic unnecessarily. Many breeders complicate the situation themselves because they are impatient for the bitch to finish whelping, and will try to rush things. The motto of obstetricians is: “the art of childbirth is knowing how to wait”.

DYSTOCIES

This term is used to describe complications that may arise during childbirth, compromising its smooth progress. There are several possible scenarios:

1 - PRIMARY UTERINE INERTIA

Also known as “uterine atony”, this is characterized by a bitch who, due to insufficient uterine contractions, is unable to expel normal-sized puppies through her normally prepared and dilated genital tract.
How can this happen? First of all, certain breeds are predisposed. Small breeds (terriers, poodles, small greyhounds) or, on the contrary, certain molosses are more prone. Poor maintenance (parasitism, malnutrition), obesity or age can predispose a bitch to uterine atony. On the other hand, it seems that bitches that have already shown uterine inertia tend to do so again in subsequent whelps. Some breeders also speak of lineages, i.e. families of dogs affected from mother to daughter.
Affected bitches seem to prepare normally for delivery, but at no time are there any real abdominal contractions to expel the fetuses. Occasionally, one or two puppies do manage to emerge, but only after hours of waiting. And then, nothing! After 3 hours of waiting without the slightest contraction, the vet on duty should be consulted, at least by telephone.
After checking that there are no obstacles in the way of the puppies' passage by means of a clinical examination and possibly an X-ray, the treatment consists of injecting a hormone that contracts the uterus: oxytocin. This substance is highly effective, and is sometimes used directly by breeders. However, it is not without danger and, when misused, can cause more harm than good. Oxytocin is sometimes combined with calcium infusions. Calcium is essential to the contracting action of the uterus, and in the case of uterine atony, particularly in small breeds, lack of calcium can aggravate the lack of uterine tone. It is therefore useful to supplement the bitch's other atony treatments with calcium.

OXYTOCIN AND CALCIUM

How does oxytocin cause uterine contractions? This hormone actually promotes the mobilization and utilization of calcium by the uterine muscle, since calcium is absolutely essential for all muscular contractions in the body.
When oxytocin isn't working well during delivery, veterinarians frequently inject calcium to try and boost the hormone's action. Calcium is often administered as an infusion or directly into the vein.
Some people also prefer to inject oxytocin intravenously, claiming that this distributes the substance more evenly throughout the body and is more effective. It's not always easy to do this, especially as it's almost impossible to connect and maintain an infusion on a bitch who's giving birth and is often very agitated.

2 - SECONDARY UTERINE INERTIA

In this case, the bitch has had normal contractions during the first stage of delivery, but at some point uterine atony sets in. This is often due to an obstruction (a puppy that is too big or badly positioned, for example). The bitch will then push and push, experiencing prolonged and sometimes painful unproductive contractions. Then uterine fatigue sets in, and everything seems to grind to a halt. If the bitch has been poorly supervised, it's not always easy to tell the difference between this and primary inertia, and only a clinical or radiographic examination by your veterinarian can tell the difference.
This is the case with medium to large-sized bitches giving birth to a very large number of puppies. When these bitches have expelled half or two-thirds of the litter, everything stops for a while, sometimes for several hours. It's as if the uterus, tired and unable to contract, needs several hours to recover.
In either case, massive injections of oxytocin will do nothing to change the uterine inertia, so it's best to adopt a reasoned approach and, when secondary atony is suspected, consult a vet without delay. Unfortunately, a Caesarean section will often be necessary to deliver the remaining offspring.

THE DANGERS OF OXYTOCIN

Puppy birth is one of the most important stages in breeding. Indeed, obtaining healthy newborns is the goal of every breeder, who is generally keen to monitor and, if necessary, assist births. For this purpose, obstetrical drugs are frequently used, first and foremost the famous oxytocin, often referred to as “posthypophyseal”, the use of which is not always harmless. There's no need to go into the exact effects and indications of this substance, which is widely used in breeding.

OXYTOCIN CAUSES UTERINE CONTRACTIONS

Oxytocin is a hormone normally released in the body at the moment of delivery, as it causes uterine contractions necessary for the expulsion of puppies. It is produced by the pituitary gland, more precisely the posthypophysis, which produces oxytocin, hence the name sometimes given to this hormone by breeders. This hormone is remarkably effective at triggering uterine contractions. We'll come back to this point later in this article, but it's worth noting that there's no need to use high doses of this substance to obtain an effect; the uterus in labor contracts without problem under the action of very low doses of oxytocin.
Injectable oxytocin is available on the market, and many breeders take the initiative of stocking it in their pharmacy before farrowing, just in case difficulties arise. But they don't always use it correctly, which can be dangerous.

OXYTOCIN ONLY WORKS IF THE BITCH IS AT TERM

The only important factor for oxytocin to really work is for the bitch to be at term. This is because oxytocin acts on the uterus via specific areas that act as coupling regions between this hormone and the uterine muscle, known as receptors. If there are no receptors, you can inject massive doses of oxytocin into a bitch, but her uterus will hardly contract at all.
However, during gestation, another hormone, progesterone, is secreted into the body. Progesterone is absolutely essential to the puppies' survival and to ensuring that the pregnancy is carried to term. If progesterone secretion stops for any reason, abortion occurs.
One of progesterone's actions is to prevent the appearance of oxytocin receptors in the uterus. In other words, as long as progesterone is released in the body, oxytocin is ineffective in triggering uterine contractions.

OXYTOCIN HAS NO EFFECT ON CERVICAL OPENING

In order to give birth properly, two factors need to come together: uterine contractions must occur to expel the young - and oxytocin plays a key role in this - but the cervix, a sort of airlock separating the uterus from the vagina, must also be open to allow the puppies to enter. This is the phenomenon of 'cervical ripening'. Oxytocin plays absolutely no role in this process.
What happens if we try to induce a birth with oxytocin when the cervix is not completely open, even though the bitch is practically full term? The uterus will contract, the puppies' placentas, which provide them with the oxygen they need to breathe, will begin to detach, but as the cervix is not sufficiently dilated, no birth will be possible. Especially if oxytocin injections are repeated, there's a real risk of asphyxiating the fetuses and, when the cervix is finally ripe and open, expelling the puppies... stillborn! It is therefore unthinkable to induce a bitch's birth with oxytocin without first checking the state of opening of the cervix. However, except in the case of smaller bitches, where a gynecological examination can sometimes examine the cervix and assess its opening, it is often impossible to judge the state of dilation of the cervix, as the vagina is too deep in the bitch. It is therefore advisable never to administer oxytocin to a bitch until the first puppy has been born or has at least entered the pelvis - it can then be seen protruding from the vulva - which is proof that the cervix is open.

DANGERS: CONCRETE EXAMPLES

Having taken this precaution into account, is the use of oxytocin without danger? Of course not, which is why veterinarians reserve this hormone for very specific indications.
First case, first danger. In the case of a bitch giving birth, an abnormally long time elapses between the expulsion of two successive puppies, while abdominal contractions are visible or have been visible. On average, newborn puppies come out every 20 to 30 minutes, and we should be concerned if a puppy is not born 2 to 3 hours after the previous one has come out. If the birth doesn't occur because the unborn puppy is blocked, due to poor positioning for example, using oxytocin to speed up the procedure is not only ineffective, it's actually contraindicated. In such a case, the oxytocin will trigger uterine contractions, thus detaching the placentas, and risk asphyxiating and killing any puppies behind the blocked puppy. When the interval between two births is too long, the first reflex should not be to inject oxytocin blindly, but to consult a veterinarian who will check, by means of various examinations, notably X-rays, that there is no blockage preventing delivery (this is known as 'dystocia').
In the second case, the bitch presents weak uterine contractions during delivery, which are clearly not sufficient to allow expulsion of the newborns. In medical terms, this phenomenon is known as 'uterine inertia'. In such cases, it may be tempting to use oxytocin to reinforce uterine contractions. The problem then lies in the origin of this uterine inertia. If it is primitive, i.e. no puppy has been born and the uterus is clearly unable to expel normal-sized puppies through the normally dilated genital tract, and if you are certain that the bitch is at term, by observing the loss of water or greenish vulval discharge, for example, which are completely normal at birth and indicate the start of placenta detachment, you can try injections of oxytocin. You can then administer 2 to 5 units per bitch, whatever her size, every 20 to 30 minutes, not exceeding 3, maximum 4 injections. After this stage, if no puppy has been expelled, consult your vet immediately.
In all cases, if a puppy is born after 1 or 2 injections of oxytocin, it is advisable to wait at least an hour before giving the next injection.
More frequently, uterine inertia is secondary, and occurs during childbirth when the bitch has already produced a few puppies without any problems, and everything seems to have come to a halt. This inertia may be the result of uterine fatigue - and this is often the case with large bitches giving birth to a large number of litters. The uterus must be given time to recover. Injecting oxytocin repeatedly, and especially in excessively high doses, into a tired uterus will not improve matters but, on the contrary, make them worse, by saturating the few remaining oxytocin receptors and desensitizing the uterus to the hormone's action. Once the uterus has “recovered”, it will no longer be able to contract sufficiently, even with the help of oxytocin, and a Caesarean section will have to be performed. In this case, it's best to refrain from using oxytocin and consult a veterinarian, at least by telephone, for advice on how to proceed.
Breeders often use oxytocin injections, especially when bitches give birth slowly but under excellent conditions, in the belief that this will speed up the procedure. This is the wrong approach. It is useless, even dangerous, to use oxytocin on a bitch giving birth normally. At best, there will be no additional effect. In the worst case, the injections may desensitize the uterus, causing secondary inertia and necessitating a Caesarean section. The breeder will thus have aggravated the case of a bitch who could very well have given birth on her own.

DO NOT INCREASE DOSES

Let's end this warning with a word about the doses of oxytocin to be used. Some people use up to 20 units per injection. In our view, such doses are excessive. They run the real risk of desensitizing the uterus (cf. previous case) and, if a puppy is blocked, uterine ruptures can - fortunately rarely - be observed following the administration of excessive doses. It's important to remember that oxytocin is very active when a bitch is at term, and increasing doses has no effect on its efficacy - on the contrary.

3 - OBSTRUCTION

This is the third type of dystocia. It is often complicated by secondary uterine inertia. There are three possible causes of obstruction. Either the puppy is proportionally too big (too globular head in certain 'flat-faced' breeds - presence of a small litter with one or two abnormally large puppies accompanying an abnormally long pregnancy which has led to exaggerated body development of the newborn(s)), or the bitch is not sufficiently dilated or has a malformation of the pelvis (fracture sequelae, narrowing...), or finally the puppy is poorly positioned and blocks the passage.
An obstruction must be diagnosed quickly. This is easy to do when you see strong, unproductive contractions in a puppy, whether or not it's in the pelvis. After 3 quarters of an hour to an hour of contractions, when the bitch often starts complaining or fussing, you need to rush to the vet and not wait. Repeated uterine contractions have the effect of 'ungluing' the placentas of all the puppies remaining inside the womb. As a result, the puppies receive less oxygen and start to weaken. If intervention is delayed too long, the puppies may be born too weak to survive, or their development may be compromised. Puppies up to 15 days old may die as a result of a difficult birth; puppies that have suffered do not 'benefit' as others do, and end up wasting away despite the intensive care the breeder can provide.

OXYTOCIN AND CALCIUM

How does oxytocin cause uterine contractions? This hormone actually promotes the mobilization and utilization of calcium by the uterine muscle, since calcium is absolutely essential for all muscle contractions in the body.
When oxytocin is not working well at the time of delivery, veterinarians frequently inject calcium to try and promote the hormone's action. Calcium is often administered as an infusion or directly into the vein.
Some people also prefer to inject oxytocin intravenously, claiming that this distributes the substance more evenly throughout the body and is more effective. It's not always easy to do this, especially as it's almost impossible to connect and maintain an infusion on a bitch who's giving birth and is often very agitated.

THE 'UTERINE MOULD' EFFECT

When a bitch is involuntarily or accidentally mated by a much larger or fatter male than herself - a cocker spaniel bitch by a German Shepherd male, for example - owners often worry that the puppies will be too big and unable to be born spontaneously.
In biology, however, there's a principle known as the “uterine mold” effect. When a female is mated with a much larger male - provided the mating takes place naturally - the size of the puppies at birth will generally match the size of the mother's uterus. Even if the puppies become very large as adults, they will not be abnormally large at birth. So it's not true that it's absolutely necessary to abort a small bitch mated to a big dog.

If in doubt, consult your vet.