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Guide to Puppy Absorption (Canine Fetal Resorption)

↯ Key takeaway points

  • Fetal resorption in dogs occurs when a pregnant female dog absorbs one or more fetuses due to infection or pregnancy problems in the early weeks of gestation.
  • It occurs in 11% of all dog pregnancies, usually undetected, and does not cause complications to the mother dog.
  • Causes of canine fetal resorption vary from infectious agents to nutritional & developmental defects and hormones.
  • Female dogs can absorb an entire litter, and the same reasons as for fetal resorption of one or two puppies apply.
  • It is not caused by ultrasounds.
Written by Xenia
Xenia is passionate about all sorts of domesticated pets. They have written dozens of articles across the web.
Zoo and wildlife doctor in veterinary medicine passionate about animal welfare and preventive medicine.
Published on
Sunday 13 May 2018
Last updated on
Tuesday 23 May 2023
Puppy Absorption (Canine Fetal Resorption)
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Puppy absorption happens when a pregnant female dog has one or several fetuses disintegrate in her uterus following an infection or another type of pregnancy problemFetal resorption in dogs can only happen in the weeks of the pregnancy when the tissues are soft and bones are not properly formed yet.

Although this is scary and worrisome for dog breeders, canine fetal resorption seems to happen in 11% of all dog pregnancies. It often happens so early in the pregnancy that it is unnoticed. Generally, absorbed puppies cause no complications to the mother dog.

What Is Puppy Absorption?

Commonly known as puppy absorption in the medical field, canine fetal resorption is a natural biochemical process where the tissues of a live fetus, in this case, a puppy, begin to break down and deteriorate. This process occurs inside the mother’s womb and leads to the complete disappearance of the organism. It is important to note that fetal absorption should not be confused with embryo loss, which happens during an earlier stage of pregnancy.

Typically, puppy absorption cannot occur after a certain number of days (approximately 44 days) due to the development of the skeletal bones, which cannot be reabsorbed. Therefore, canine fetal resorption only takes place during the early stages of pregnancy when the fetus is mostly composed of soft tissues.

It is worth mentioning that most cases of puppy absorption involve only one or two puppies in a litter. However, it is possible for an entire litter to be absorbed.

Unlike a miscarriage, the fetus does not leave the mother’s body after its death. During fetal resorption, the mother’s body absorbs the placental tissue first and then the fetus itself. The reabsorbed puppy essentially disappears from the litter and the uterus. This natural chemical process might be confusing to those unfamiliar with the term, as the puppy’s body dissolves. However, this systematic approach actually benefits the mother, as it eliminates the risks associated with aborting a fetus while the other puppies continue to develop and survive until birth. The process of absorption ensures the mother’s safety and successful delivery.

Another term used to describe this process is “Vanishing Twin,” which refers to the situation where the remains of the reabsorbed fetus can be taken up by the other twin or the mother. Although it may seem daunting to unsuspecting dog owners, this phenomenon is quite common and is a natural part of canine reproduction. Various studies indicate that around 11% of dogs experience fetal resorption on average

Causes of Fetal Resorption in Dogs

There are various reasons that can lead to the absorption of puppies. Some believe that it is a natural occurrence and may serve as nature’s way of preserving the deceased or protecting the mother for survival. Regardless, it is important to consider the timing of reabsorption as a useful indicator to understand why it occurred in the first place.

The causes of puppy absorption can vary from dog to dog, depending on several factors. Often, dog owners are unaware of reabsorption because the process can go unnoticed. A puppy can be reabsorbed before the owners even realize that the mother is pregnant, and in such cases, the cause can never be determined. However, if a reabsorbed puppy is detected and confirmed alive but later found dead, observing coinciding events and the status of other pups can help establish a logical reason for the reabsorption. Some absorptions can be caused by infectious agents, while others are caused by non-infectious factors.

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Infectious

  • Brucella Canis — Commonly referred to as Brucellosis, the Brucella Canis bacterium can cause infection in the dam by affecting her reproductive organs and is even considered to be highly contagious. Brucellosis is responsible for a number of stillborn pups in many dogs of all ages and has been known to even cause infertility.
  • E. Coli — Escherichia coli is a very common bacteria found in a canine’s bloodstream that causes the disease known as colibacillosis. Taking preventative measures in pregnant canines goes a long way in avoiding this condition. Owners of pregnant dams are advised to give adequate nutrition to her as well as keep her in highly sanitary conditions. Other bacterial agents that can cause reabsorption are Streptococcus spp. and Staphylococcus aureus.
  • Canine Herpesvirus — This canine virus belongs to the Herpesviridae family and is most commonly referred to as the virus that causes fatal hemorrhaging. In fact, it’s a documented fact that this disease is the leading cause of fetal deaths in puppies. The most unfortunate aspect of this virus is its 100% mortality rate for the affected puppy litters.
  • Parasites — This parasite causes an infection called toxoplasmosis. These parasites are known to reside in the feces of cats and other times in the roots of contaminated soil or even unwashed fruits and vegetables.

Non-infectious

  • Genetics — The genetics of the pups can play a role in whether or not the fetus will be properly developed. Some genetics may cause malformations or even not allow full development to occur to allow survival, thus allowing for reabsorption.
  • Drugs — There are certain drugs that are given to dams that may affect the developmental stages of the whelp. It is possible that an adverse drug reaction may have been the cause of any of the pups in the litter to reabsorb.
  • Nutritional — All mothers, whether canine or human, require sufficient nutrition to withstand a pregnancy. The nutrition of the mother affects the babies and therefore, any malnutrition can cause early death in the fetus.
  • Developmental/Chromosomal Defects — Any anomaly or defect found in any of the developmental stages can result in early death to a canine fetus. Chromosomes assist in the development and growth of the cells and sometimes even breeding the canines at inappropriate times can lead to defects. Sperm and egg cells, as a result of this, may deplete or lose all function leading to eventual death.
  • Hypothyroidism — Certain endocrine disorders such as hypothyroidism can warrant unwanted effects on the fetus of a canine often leading to aborted fetuses.
  • Placental or Uterine Anomalies — The placenta and the uterus of the pregnant mother are the main organs that allow for a successful birth, so any disruption in the formation of the fetus can lead to some serious risks and even death.
  • Hormones — This seems to be one of the most common causes of fetal absorption in puppies. Adequate hormones are needed to develop ideal conditions in the dam’s body for reproduction and development of the fetuses to occur naturally.
  • Environmental Stresses — Stress can wreak havoc on the body especially during pregnancy. If any environmental stresses become too unbearable the body can begin to stop functioning at its optimum level and thus, lead to various complications which may lead to fetal resorption.
causes of puppy absorption
Younger female dogs and first-time canine mothers tend to be more at risk with puppy absorption.

Other Causes

It’s important to note that younger dogs are more susceptible to canine reabsorption than older dogs, therefore one could take into the account the age of the dog during pregnancy to consider if this may have been a possible cause of the absorption. Another probable factor could be a false reading of how many puppies are found during the ultrasound. It is possible that the ultrasound operator could have made a mistake in the puppy count. In addition, false pregnancies have been known to cause pregnancy symptoms such as milk production and enlarged abdomens, thus leading to a false idea of impregnation when in fact there are no eggs fertilized.

Although it’s not often the case, traumas and accidental events can cause some puppies to be absorbed. A hard blow to the dam or a fall can prove to be fatal if the impact is substantial enough to cause lesions to the uterus, placenta or other major bodily organs involved in the development of the pups.

What Doesn’t Cause it

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It’s a common misconception that canine absorption is caused by ultrasounds. For those who are familiar and well-read in the reproductive cycle of dogs may have heard of Dr. Hutchison, an expert in canine reproduction. In one of his leading seminars, the topic of canine resorption came up and Dr. Hutchison had claimed that the idea of ultrasounds being a cause of canine absorption is nothing but an urban legend.

Can a Female Dog Absorb an Entire Litter?

Although the majority of canine fetal resorptions occurrences often happen to only one or two puppies in the litter, it is possible that a female dog absorbs her entire litter as well. There have been some instances in which some dogs have looked pregnant and all the sudden, no longer have their bellies. That could be a sign where the dam has lost all of her pups due to absorption. This would be a full-on canine miscarriage.

The same reasons that cause one of the fetuses to reabsorb also applies to the entire litter. Diseases and malnutrition to the dam can cause an array of issues that result in the loss of her pups if all of them become affected and thus, too weak to cope. It is also possible that infectious agents such as bacteria and viruses may pass on to all the fetuses and result in a spontaneous litter absorption. Unfortunately, in these cases in which all puppies are reabsorbed, a lack of sufficient information results in unanswered questions. Because there are no survivors in an absorbed litter, there is no way to make comparisons with other puppies that will help indicate a cause.

11 comments on “Guide to Puppy Absorption (Canine Fetal Resorption)”

  1. Verona

    Hi, my name is Verona and I am currently studying genetically altered dogs and very much would like some info and breeders to help and further me with this venture.

  2. Lynnette

    Hello. My name is Lynnette and I have a question about puppy reabsorption that I cannot find answer to anywhere else…. If a bitch reabsorbs her puppies (entire litter, likely small litter) will she still have labor signs later on around her due date?
    Thanx

    1. Lindsay collins

      I would like to know this as well and can the dog breed again ??

      1. M cohee

        I too would appreciate information on this topic. Will the fog be able to carry a litter to it’s full fruition in the future.
        Secondly, Are the illnesses that are linked to canine resorption curable?

    2. Roman Rodriguez

      My female at 2 months off being pregnant started to ho into labor. This is her second litter. One was half way out,and when I looked again, apparently went back in.she has pushed out 3 over a 24 hour period. But all 3 pup’s were very undeveloped. And believe she has more.can a dog go into labor early to get rid of the pup’s that were undeveloped. And still continue to carry the rest till she or they are ready to be born.

  3. Hello
    One of my dogs, Coco, has reabsorbed a most of a litter, twice. But produced a perfectly good litter in between. I am interested in this subject and any procedures and tests that can help diagnose why, and avoid it next time.
    My Coco, Cavalier King Charles Spaniel bitch is currently 4.5 years old. She is a fully health tested ( eyes, heart DNA for DE/cc and EF, and has a perfect MRI scan Cm0/SM0.). I have been breeding cavaliers for 22 years and have always fully health tested from the start. She comes from 5 generations health tested clear sire and dams, and really good brood bitches who carry good sized litters and whelp naturally.
    In early spring 2019 she was mated to a 6 year old, health tested outside stud dog. She was scanned at 4 weeks with 5 puppies. At 9 weeks she produced one dead puppy, after not visibly going through a proper stage 1 labour. A scan showed she she has reabsorbed the rest. I was advised by my vet to use a different sire next time.
    6 months later I mated her to my own young stud dog, Robbie. He had already produced a superb litter of 7 by accident, to this bitches half sister, Maddie.In October 2019 Coco produced a litter of 7 pups whelped naturally by Robbie.
    This year I mated her to a different outside sire. The same thing happened as first time. Because of COVID and lockdown I could not get her scanned at 4 weeks. But she showed every sign of being pregnant, nipple enlargement, expanding waistline, even by 4-5 weeks. In my breed this indicated a good sized litter. In her first pregnancy she didn’t look visibly pregnant and stayed quite slim. In this third pregnancy she remained very pregnant looking. On wed 30th dec 2020, she again produced one dead but perfectly formed puppy. A scan at the vets revealed debris associated with resabsorption of other foetus.

    1. Janet

      I by no means am a professional bit just going through my girl absorbing her litter midterm. We then tested her progesterone. It had dropped to 9.8 where it takes 20 or greater to maintain a pregnancy. If the bitch carry’s 35 days she can be given progesterone supplementation to maintain the litter.

      1. Robyn Hoem

        Hi
        My bitch has had one litter of puppies and absorbed the last two litters, just wondering when do you check progesterone level? That is a good possibility. Worth a try and at what time to give progesterone

      2. Sammi

        How do you test this please?
        I am literally just from the vets after being told 2 days overdue that there are no puppies at all (had scan at 36 days showing 4puppies)

        1. Wanda

          Hi Sammi, I’ve just come from the vets myself 2 days over due to be told no pups after a scan at 34 days confirmed 3. sad times xx

  4. Debbie

    We are planning on getting a puppy. Originally we were told the mom was pregnant with 10 pups. At her last ultrasound there were only 2. She safely delivered the 2 puppies. Do you think the reabsorption of the 8 fetuses has any effect on the surviving puppies?

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