-A +A

Early detection

The importance of progesterone in maintaining Mastiff pregnancies and avoiding reabsorption
When and how much to intervene in the canine reproductive process is a decision many breeders face. Many breeds would not exist without human intervention beyond selective breeding. Some require little or none. From progesterone testing to Caesarian sections, many tools are available to today’s breeder. But the most valuable tool in the breeder’s toolbox is knowledge.
We have tools to help us get our bitch pregnant, such as testing to determine when our bitch has ovulated, and options to ensure a successful delivery, such as C-sections, but what happens in between? Sadly, many bitches are confirmed pregnant either by visual observation or by ultrasound, yet puppies can be lost before they are full term.
Many breeders and even many veterinarians are not aware that there is a way to save some litters lost due to a premature drop in progesterone in the bitch. Breeders may choose not to intervene for one reason or another. But after all the effort involved to produce a pregnancy, many breeders will use whatever tools are available to maintain that pregnancy and ensure the survival of those precious puppies.
In February 2000, I was expecting a litter of Mastiff puppies. It was my third litter of Mastiffs. I had previously whelped Basenjis, English Springer Spaniels and Great Danes. All those pregnancies were normal, with puppies whelped naturally within a day or two of the anticipated due date. I had a lot to learn about the art of breeding.
I left my pregnant bitch with a friend while I travelled to visit family in Wisconsin, thinking there was no way puppies would arrive before I returned to Texas. My friend called concerned that “Gypsy” was restless and didn’t seem to feel well.
It sounded like she was in labor, but that didn’t make sense to me. There is a relatively small window during which pups can be delivered and survive, and delivery prior to 56 days post LH peak is not normal and is actually considered a late abortion. Of course, it was Sunday, and at that time the only option we thought we had was a local animal emergency clinic. The vet on call that afternoon called to discuss Gypsy with me. Although she had some vaginal discharge, it was his opinion that Gypsy was not in active labor. We expected to be able to get to the clinic that night and asked him to keep her for observation.
We soon got another call because Gypsy had delivered an underdeveloped, stillborn puppy around 6:15 p.m. Despite that, the vets at the emergency clinic did not believe she was in labor and believed she may not deliver any of the remaining puppies. I was able to reach two other veterinarians by phone to ask for advice. Opinions varied. Perhaps there had been something wrong with the aborted puppy. Perhaps Gypsy had an infection. Other puppies might be okay, but they might not be. Gypsy was started on antibiotics. No one mentioned progesterone levels.
We arrived at the ER clinic at 10:30 p.m. to find Gypsy anxious and restless, but she had not delivered any more puppies. We took her home and thus began the vigil that lasted over a week. There is a clinic in Houston, more than an hour from my home, with veterinarians that have a special interest in canine reproduction. I planned to be at their door with Gypsy when they opened Monday morning.
Gypsy made it through that Sunday night without further incident, but as I was getting ready to leave in the morning, she delivered another puppy that was alive and squirming. With my help and Gypsy’s, he was soon breathing on his own. He was tiny and looked more like a fetus than a puppy. He struggled to keep breathing and had no interest in nursing. I held him under my shirt against my skin to keep him warm and so I’d know if he stopped breathing all 55 miles to the clinic in Monday morning’s rush-hour traffic.
The vet took one look at the puppy and shook his head. He put him in an incubator and turned his attention to Gypsy. A quick ultrasound showed heartbeats and live puppies. She still had at least 10 days until her due date, and there was no indication that it would be dangerous to attempt to halt labor and try to delay delivery until closer to this date.
No help needed here: British breeder Ianthe Bell with Heatherbell Portia of Goring and some of her 12 puppies whelped in 1950. Photo courtesy Molosser Magazin.
A hormone that plays a vital role in canine reproduction, progesterone is present and rising during the heat cycle of a bitch, reaching a maximum level approximately ten to 25 days after ovulation. Progesterone produced by the corpora lutea, which form after the ovarian follicle ruptures and the bitch ovulates, is required to maintain pregnancy. Without sufficient progesterone, the bitch will resorb, abort or whelp prematurely.
Gypsy’s progesterone level at that time was 0.4 ng/ml (nanograms per milliliter). When progesterone levels drop below 2 ng/ml, puppies usually are born within 24 to 48 hours. Gypsy was given a shot of progesterone in oil to increase the level to one that would sustain pregnancy, as well as terbutaline by mouth to stop contractions since she was in active labor. Although terbutaline had been used for many years to stop contractions in humans, at that time it was not well known nor commonly used in veterinary medicine. In Gypsy’s case, she required terbutaline every three to five hours from then on; without it, she would resume having contractions.
Sadly, the premature puppy only survived about 12 hours. I dropped Gypsy off at the clinic every morning on the way to work and picked her up every evening on the way home. I checked her and gave her the terbutaline every three to five hours through the night. Frequent ultrasounds were performed to confirm we still had live puppies, and Gypsy’s progesterone level was monitored. We administered more progesterone via injection as needed.
The plan was to let her have the surviving puppies the following Monday, eight days after she aborted the first stillborn puppy. Although that was still a bit early, it was within the window of viability for the puppies. We stopped the terbutaline Sunday night. Unfortunately, she delivered another stillborn puppy right before we left for the clinic Monday morning. One last ultrasound confirmed there were still live puppies, and the decision was made not to stress them with labor and delivery, and a c-section was performed.
Although the remaining four pups were still early, about half the size of average Mastiff puppies at birth, and one required resuscitation, they were soon nursing and seemed healthy. They all survived to adulthood with no ill effects. The two girls subsequently produced litters. One required progesterone supplementation; one did not.
Because I had no idea that progesterone might drop prematurely, we were unaware there was a problem until Gypsy actually was in labor. Thus, her case became far more critical and complicated than it might have been had we known and tested her throughout her pregnancy.
I did a lot of research after that experience, and with every litter I’ve had since then, I test progesterone again as soon as I confirm pregnancy and periodically until the puppies are born. I have heard from breeders who choose not to intervene and feel that a bitch that cannot successfully maintain a litter should not have puppies and possibly perpetuate reproductive problems. That is a choice each breeder must make for herself. But it is a choice. Just like using artificial insemination is a choice and delivering via C-section is a choice. To make the decision, breeders need awareness and knowledge.
Three colors/patterns of Mastiff puppies: brindle, fawn and apricot.
Let’s back up and look at the entire process involved in producing a litter.
I must start with the admonition that if you are not prepared for the costs in time, money and heartache if complications arise, then you should not plan a litter. Some breeds seem to be able to breed naturally, easily conceive and carry their litters and whelp naturally, with little or no intervention on our part. And then there are Mastiffs.
It has been a common practice to breed on the ninth, 11th and 13th days after the first obvious signs of heat because these times, on average, have resulted in conception. More and more serious breeders now are using progesterone testing to determine their individual dogs’ fertile period. The level is assessed through blood testing. The timing of the fertility period can vary greatly from bitch to bitch and even for different cycles of the same bitch.
Progesterone is just one of the several hormones that interact during the reproductive cycle. The primary hormonal event, and the one that most accurately predicts the timing of ovulation and thereby the fertile period, is a surge of luteinizing hormone. This LH surge generally occurs between the eighth and 12th days after the first noticeable signs of heat, i.e., swelling and/or discharge. The LH surge, however, can take place anywhere from the third to the 28th day! Ovulation occurs two days after the LH surge and the resulting eggs are ready to be fertilized approximately two to three days later and live another 48 to 72 hours after that. So, the bitch’s fertile period is four to seven days after the LH surge.
Blood tests can be used to determine when the LH surge occurs, but because this surge may last only 24 hours, the test must be done daily. Another way to determine the timing of the LH surge is to test the bitch’s progesterone level. The progesterone level increases significantly at the same time the LH surge begins. Progesterone continues to increase, reaching the maximum level from 15 days to 25 days after the LH peak. Because the rise in progesterone is more gradual and the duration longer, and because the LH surge and progesterone levels are linked, breeders can test progesterone levels every two to three days and still accurately identify the timing of the LH surge.
Once the optimal time for breeding is determined, we must decide how to accomplish the actual breeding. Although, theoretically, I love the idea of letting dogs breed naturally, in practical terms that isn’t always possible or even advisable. My other breed, the Spinone Italiano, is so much easier as far as reproduction is concerned. They generally breed naturally without any issues. I’ve never had one drop progesterone early. Whelping is generally natural and without complication. They are fantastic mothers. And then I have Mastiffs! But even with the Spinone, there are reasons to consider artificial insemination (AI).
Sometimes a bitch simply will not stand for the stud dog. Or she might start out being receptive and change her mind after it’s too late and either she or the stud dog can be injured. If we do a natural breeding, we do not have the opportunity to assess the quality of the semen, which might alert us that we need a different stud dog and explain why the bitch may fail to conceive. Sometimes the stud dog is not nearby and semen can be shipped fresh chilled. Or we may have the opportunity to use frozen semen for a dog long deceased.
Semen can be freshly collected from a stud and used immediately after evaluation. Cooled or extended semen can be collected and used within 24 to 48 hours. Semen can be “extended” by adding a buffer to prolong the life of the sperm. This can allow the breeding between dogs geographically distant without the risk and stress of shipping the animals. Semen can also be collected and frozen using liquid nitrogen and can be stored for many years.
AI is accomplished via three different techniques. Vaginal insemination is the simplest. Semen, which ideally should be freshly collected, is deposited into the vagina with a rigid tube. There is no need to sedate or anesthetize the bitch for this procedure. Although vaginal insemination is quite successful, it may not be the ideal choice for dogs the size of Mastiffs.
Surgical insemination (intra-uterine implantation) requires anesthesia. A small incision is made in the dog’s abdomen. The vet can visually and manually assess the condition of the bitch’s reproductive organs and verify that she is a good candidate for a successful pregnancy and delivery. For example, some bitches have uterine cysts so that implantation in the uterine wall can’t occur or is limited. This can be identified during surgical insemination. The semen is deposited directly into the uterus with a small-gauge needle. This technique can be used with fresh (cooled or extended) or frozen semen.
The third technique is trancervical insemination. In this procedure, semen is deposited in the uterus by passing a flexible tube through the cervix. The progress of the tube is determined by manual palpation through the abdominal wall or ideally by using an endoscope to view the cervix. The bitch generally requires no sedation for this procedure.
The author showing Ch. QuietWood God of Thunder to his championship at the tender age of 10 months. "Thor" wouldn't have existed if she had not used progesterone supplementation on his grandmother, Gypsy. His mother, by contrast, did not require any pregnancy support.

So, the breeding has been accomplished, and we wait to see if it is successful. An experienced veterinarian can confirm pregnancy as early as 22 days after ovulation by using ultrasound equipment. The embryo and cardiac activity can be detected 23 days to 25 days after the LH surge. Limb buds and fetal movement can be seen around day 35, and the skeleton becomes identifiable sometime between day 33 and day 39.
Some breeders just wait and watch for visual signs of pregnancy. Personally, I choose to verify pregnancy via ultrasound, after which I’ll start watching progesterone levels. If the bitch is not pregnant, there is no need for me to test her. Note that progesterone levels should remain high whether or not the bitch is pregnant. It is not an indication of pregnancy.
Many breeders calculate the due date for a litter by counting 63 days from the date of a natural breeding. The due date is more accurately timed by counting 65 days from the LH peak, regardless of specific dates of natural breeding(s). This is another good reason to do LH or progesterone timing. Sperm can live a long time in the bitch’s reproductive tract and conception can occur a week or more after a natural breeding. Predicting the due date is far more accurate using the science available to us and allows us to be there for whelping or plan a successful C-section.
Sometimes, a bitch may go into labor early for a variety of reasons. First, some or all of the fetuses may have died. She might be suffering from conditions such as pyometra (a severe bacterial infection with accumulation of pus in the uterus). Or, it’s possible that the due date has been calculated from the time of natural breeding and not the LH surge and the labor is not early at all. In these and certain other circumstances, the absolutely wrong thing to do is to stop the process of labor and delivery. Doing so under the wrong circumstances could have severe, even fatal consequences.
In the case of my Gypsy, and many other bitches, early labor can be caused by a premature drop in progesterone. There is a natural, gradual drop in progesterone toward the end of pregnancy, but once it drops below 2 ng/ml, pups will be born within 24 to 48 hours. In Gypsy’s case, we did not know to check progesterone after we did the breeding. Yet even though we lost two puppies, we were able to save four by supplementing progesterone. Had we known to check and been aware of the premature progesterone drop before she went into labor, we may have saved them all.
I now resume checking progesterone once I confirm pregnancy, at about the halfway mark, but if a bitch has a history of resorbing or aborting litters without evidence of infection, a breeder should probably test weekly starting seven to ten days after breeding. I use a kit at home that allows me to do everything myself and get results within an hour. If you are not able to do that, I’d highly recommend using a vet who can get results quickly, not the next day, as that may be too late.
If my bitch drops to a level that concerns me with my home test, I take her to the veterinarian so he can assess using the test he is comfortable with. But doing it myself saves me a lot of money and many long drives. If all goes well and I don’t catch a premature drop, testing at home also tells me if I need to be on puppy watch, or if I can get one more good night of sleep, or take the time to go grocery shopping. If I’ve planned a C-section, I prefer to see a drop before the C-section, as it seems the bitch is more likely to produce milk and accept the puppies. If there isn’t a drop and we are still in the window of viability, I may delay the C-section a day or two.
It should be noted that in 21 years of breeding Mastiffs, I’ve had to supplement three bitches, the most recent was in 2015 and the result of that litter was a nice litter of nine puppies. One of the girls from that litter was bred and had a successful litter without progesterone supplementation.
Different vets and different tests use different parameters, so be sure you understand what scale is being used and what the numbers mean. I’m familiar with tests that measure ng/ml. Numbers using other tests might be quite different, but can be converted to compare to ng/ml. One, for example, measures in picograms per millilitre. If you are breeding Mastiffs or related breeds, it’s a good idea to discuss everything with your vet ahead of time. Not all vets keep progesterone in oil on hand, as it has a limited shelf life. When you need it, you need to know it can be available quickly, so plan ahead. Some vets recommend using a synthetic progesterone marketed for horses that is given orally, and it may not be readily available, either. This is a non-native progesterone that cannot be measured by blood test, so that is a consideration as well. Not all vets are aware that supplementing progesterone can save a pregnancy, so plan ahead.
Find a vet who is familiar with progesterone supplementation or willing to learn about it. Supplementation should not be done unless it is needed and safe for the bitch and puppies. As mentioned previously, sometimes there are reasons it is not safe to maintain a failing pregnancy.
Aside from a premature drop in progesterone with no indication of infection, like Gypsy faced, there can be other labor and delivery complications. Among them are:
Dystocia. This is a painful, slow or difficult delivery and can be caused by the size, shape or position of the puppies, or a deformity or inadequacy (such as weak uterine muscles) of the dam.
Physical abnormalities. Anatomical aberrations of the dam can make delivery difficult or even impossible. For example, strictures, which are tough bands of tissue, may block the birth canal (and can also prevent natural breeding); the pelvis might be flattened or narrow; the cervix or vulva may not dilate completely; the uterus might twist; or scars from previous surgeries or deliveries may hinder the progress of the fetus or keep the uterus from contracting properly.
Primary uterine inertia. This condition involves weakness of the uterine muscle. It can occur with hypoglycemia, if the dam is in poor condition, and from overstretching caused by a large number of fetuses or placental fluids. Secondary uterine inertia can follow exhaustion from a long labor. Uterine inertia is not uncommon in Mastiffs. Some will deliver a few puppies normally and then labor just seems to stop and an emergency C-section may be required. In any case of uterine inertia, no steps should be taken to increase the strength of the contractions, such as administering oxytocin, without making sure there is no obstruction or abnormality.
Canine brucellosis. This disease can cause third-trimester abortion. All dogs used for breeding should be tested for brucellosis prior to breeding. A dog can acquire brucellosis without having been bred.
Some breeders do not believe that we should take extraordinary steps to produce puppies and save litters that require intervention. They believe that we may perpetuate reproductive problems. There is not a lot of research to support nor refute that concern. We intervene in various ways when it comes to breeding. Some breeders give up on a breeding without turning to science. I think we are intervening simply by breeding selectively and maintaining separate and distinct breeds. I think the line we shouldn’t cross is very blurry. Personally, I embrace science and the options it provides. Once I know I have a pregnancy, I will do whatever I can to save those puppies. Just like once those puppies are born, I’ll step in as necessary to help them grow and thrive. With Mastiffs, that may require tube or bottle feeding.
Many litters may be saved with progesterone supplementation under the care of a vet who can determine it is safe to do so for the dam and the puppies. It is a decision best made ahead of time rather than in an emergency. Although supplementation may be discontinued and the bitch may then whelp naturally, often a C-section is necessary or the best option. In my personal experience and from information I’ve gathered from other breeders, a bitch that requires supplementation for one pregnancy may not need it for a subsequent pregnancy. Female puppies from a supplemented bitch may or may not require supplementation for their own pregnancies. Puppies from supplemented litters seem to be healthy and develop normally.
Breeders need to be aware of the possible complications and potential solutions when it comes to canine reproduction and related issues. Hopefully litters that might otherwise be lost can be saved if breeders and veterinarians are aware of and prepared for possible interventions. If a breeder feels strongly that the resulting puppies might have or pass on fertility or reproductive problems, they can be spayed/neutered, removed from the gene pool, but still be loving companions in loving homes. In the end, nothing beats the joy of healthy, happy puppies.



© Modern Molosser Magazine. This article may not be reposted, reprinted, rewritten, excerpted or otherwise duplicated in any medium without the express written permission of the publisher.