Guide to Puppy Absorption (Canine Fetal Resorption)

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 problem. Fetal 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.

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.