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Ask a Vet: Puppy Absorption (Canine Fetal Resorption): 2024 Guide

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By Dr. Joanna Woodnutt

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Dr. Joanna Woodnutt

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Breeding dogs can be a wonderful experience but can come with lows as well as highs. Losing puppies in the womb is a devastating experience, though thankfully not that common—only 11%–13% of fetuses seem to be affected.1

But why does this happen? Is there anything we can do to prevent it? We do know some of the reasons why this happens, and thankfully there are some measures that we can take to try and avoid these risks, but sadly it remains a possibility in any pregnancy.

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What is Puppy Absorption?

If a puppy sadly passes away whilst it is in the uterus (the technical name for a dog’s womb), then there are several different things that may happen to the puppy’s body. Absorption is one of these, but there are others, too. Which one occurs will depend on the stage of pregnancy, and also on the reason why the puppy died.


Absorption is where the puppy’s body is re-absorbed by the dam (mother dog), instead of passing out the birth canal. It normally happens in the first half of pregnancy (up to around day 30) but can happen later on, too. This means that there are usually no outward signs, such as vulval discharge or signs of illness in the dam, that suggest anything is wrong.

Often only one or two puppies in the litter will be absorbed, and their siblings will continue to develop and be born as normal. Occasionally, the whole litter may be lost in this way.

brown dog ultrasound
Image Credit: Ermolaev Alexander, Shutterstock


Mummification can occur in the later stages of pregnancy when a puppy dies but their body remains within the uterus. This normally happens if a puppy dies after their skeleton has formed, around day 50 of pregnancy. The body will dry out due to a lack of blood flow but still remains recognizable on X-rays and ultrasound scans.

The rest of the litter may still continue to develop normally, and the mummified body will then be passed out when the dam gives birth. This is thankfully a rare form of pregnancy loss, but still seen occasionally.


Puppy abortion occurs when a dam goes into labor prematurely, and delivers puppies who are too premature to survive. This can happen at any stage of pregnancy but is more common after day 30 when the dam’s body is no longer able to resorb the puppies.


Stillbirth is when a dam gives birth to fully developed puppies who have passed away in the uterus shortly before being born.

chihuahua giving birth
Image Credit: boyphare, Shutterstock

Why Does Puppy Absorption Happen?

Puppy absorption happens when a puppy passes away in the uterus during the early stages of pregnancy (usually up to day 30). The uterus will then absorb the unformed pup’s body back into itself, leaving very few traces behind.

There are many different reasons why puppies will pass away in early pregnancy, but these are some of the most common.


Viral Infections

If the dam becomes infected with a virus early in her pregnancy, this may cause the puppies to pass away, and then their bodies to be resorbed. The two most common viruses to cause this are Canine Herpesvirus-1 and Canine Parvovirus-1. Canine Herpesvirus-1 attacks the placenta, cutting off the puppies’ supply of oxygen and nutrients. Canine Parvovirus-1 (also known as Canine Minute Virus) damages the puppies directly.

In both cases, the puppies pass away as a result of the infection. If this happens in the first month of pregnancy, the puppies’ bodies are often then resorbed.

Bacterial Infections

There are several different types of bacterial infections that can cause pregnancy loss in dams. The most common of these are “opportunistic infections”, where bacteria that are normally present in a dam’s vagina manage to move up through the cervix and into the uterus. The bacteria then breed in the uterus and create a toxic environment, which is usually fatal to puppies.

There are many different species of bacteria that can infect the uterus in this way, including:

  • Streptococci
  • Staphylococci
  • coli
  • Pasturella
  • Proteus
  • Pseudomonas
  • Klebsiella
  • Morexellae
  • Haemophilus

If this happens early on in a pregnancy, then the puppies may be resorbed after they pass away. In the later stages, this can lead to abortion instead, with large amounts of vulval discharge that may be foul-smelling. In some cases (most commonly with Staphylococci and E. Coli) this can also lead to the release of toxins into the dam’s bloodstream, making her very ill.

Brucella Canis

Unlike opportunistic infections, Brucella Canis is a bacterium that has evolved specifically to infect dogs. It generally passes between them during mating, or when dogs come in to contact with the placentas of an infected litter. The symptoms that it causes can vary widely, but male dogs commonly have sore, swollen testicles. Many dams do not have any symptoms besides infertility.

If dams are infected when they mate, then the infection passes into the uterus and infects the placentas. This usually causes the puppies to pass away, and the dam’s body will then resorb them, so it will appear as though she has never been pregnant.

Occasionally, the infection does not cause the puppies to pass away until later on in the pregnancy, in which case abortion will occur, and discharge will be seen from the dam’s vulva. Thankfully Brucella is an uncommon infection in many parts of the world. Higher rates are seen in the southeast US compared with other parts of North America.


Parasites are thankfully a rare cause of puppy absorption, but infections such as Toxoplasma gondii or Neospora caninum can cause pregnancy loss in dams.

Genetic Conditions

A significant number of puppies who do not survive birth have genetic health conditions which mean they are unable to develop properly. This is normally due to random mutations in the DNA of the egg or sperm that made the puppy, rather than anything they have inherited from their parents.

These kinds of mutations are thought to be more common in older dams, which may put them at increased risk of pregnancy loss.

Stress or Ill-Health in the Dam

If the dam is unwell for another reason (not related to pregnancy), or very stressed over a period of time, then this can cause changes in hormonal levels and affect blood flow to the uterus. This can sadly result in the death of the growing puppies, and (if it occurs in the early stages of pregnancy), puppy resorption.

sick dog
Image Credit: Igor Normann, Shutterstock

Low Progesterone

Progesterone is an important hormone for pregnancy and helps to keep the uterus a safe place for the growing puppies. Some dams will have low levels of progesterone, which can lead to pregnancy loss including puppy resorption.

This is thankfully uncommon, but if a dam has issues with the loss of puppies in multiple pregnancies, then they can have their progesterone levels tested.


Several different medications will cause pregnancy loss in dams that will lead to puppy resorption. Some of these, such as aglepristone (Alizin®) are used to deliberately terminate unwanted pregnancies. Others are used to treat unrelated medical conditions but can cause pregnancy loss if accidentally given to a pregnant dam.

The most important of these are steroids such as dexamethasone, prednisolone, or hydrocortisone, as these are commonly used medications in veterinary medicine. They should only be given to pregnant dams if there is no other alternative.

Unknown Reasons

Unfortunately, often the exact cause of a puppy being resorbed is not known. As it is not uncommon in canine pregnancy (11–13% of fetuses may be affected) then it should not be taken as a bad sign, especially if the dam is young.



What are the Symptoms of Puppy Absorption?

One of the difficult things about fetal resorption is that there are often no outward symptoms that it is happening. The puppy’s body is absorbed back into the mother through the uterus, so there is no vulval discharge. The process is not thought to be uncomfortable for the dam, and so there may be no changes to see in her.

Often only one or two puppies in the litter are affected, and so the pregnancy may carry on regardless. Occasionally, all the puppies may be lost, in which case it can appear as though the dam is just having a phantom pregnancy. Unless an early ultrasound is done, the original number of puppies—or the fact that a pregnancy was present—may never be known.

chihuahua ultrasound
Image Credit: Andrii Medvednikov, Shutterstock

Can Puppy Absorption Be Treated?

Sadly, once the process of absorption has started, there is no way to save the puppy. If there is an issue that may affect the whole litter (such as an infection) then treating this may save the other puppies, but unfortunately this is not guaranteed. Generally, it is best to try and prevent these issues rather than treating them when they happen.

Can Puppy Absorption Be Prevented?

Losing puppies during a pregnancy can be devastating. Some causes of puppy absorption, such as genetic abnormalities, are an inevitable part of pregnancy in dogs and cannot be avoided. But there are steps that you can take to try and reduce the risks from other causes.

Ways to Prevent Puppy Absorption

1. Get a Checkup

Before mating your dam, make sure she is in good general health. She should be a healthy weight (not too fat, not too thin), up to date with flea and worm treatment, and exercise regularly. A check-up with a veterinarian is also advised to make sure there are no obvious underlying health conditions that might affect the dam’s pregnancy or the puppies.

pug ultrasound
Image Credit: Ermolaev Alexander, Shutterstock

2. Vaccination

There is a vaccination available against Canine Herpesvirus-1 (Eurican® Herpes 205). It is proven to give protection against sickness to newborn puppies, but may also help to reduce pregnancy loss. It must be given either when the dam is on heat or 7–10 days after mating, and then again 1–2 weeks before the expected due date.

You should also make sure that the dam is up to date with their routine vaccinations, to prevent them from becoming unwell whilst they are pregnant.

3. Brucella

The most common way for dams to catch Brucella canis is from the male during mating, so if you live in an area with high rates of the disease, try to choose a stud dog who is regularly tested and known to be free from the disease. At a minimum, the dog should be vet-checked and appear healthy, and have never suffered from redness and swelling of the testicles.

4. Hormone Therapy

Dams who suffer from low progesterone levels may benefit from being given medication during pregnancy to supplement this, but this should only be done if tests have confirmed this is an issue. You may need to see a veterinary reproductive specialist for advice on this.

5. Avoid Infection Risks

Good general hygiene at home and in the kennel is essential to keep a dam healthy during her pregnancy. This includes regularly washing bedding and food bowls and cleaning down any kennels or outdoor runs. You may wish to avoid mixing pregnant dams with large numbers of other dogs, particularly ones she does not live with, in order to minimize their risk of catching an infectious illness.

You may also wish to avoid the dam coming in contact with sheep or cows, particularly pregnant ones or those who have recently given birth, as they can be a source of Neospora and Toxoplasma infections.

6. Diet

There is some evidence to suggest that feeding a diet rich in protein and fatty acids may help to reduce the risk of puppy resorption. Fatty acids such as docosahexaenoic acid also aid brain development in puppies, so can be a useful addition to a pregnant dam’s diet. Speak to your veterinarian for advice on which supplements are safe to use during your dog’s pregnancy.

French bulldog eating from bowl
Image Credit: Gryllus M, Shutterstock

What Does Not Work

Some of the infections that can cause puppy absorption can be treated with antibiotics, but it is not recommended to give these preventatively (i.e., before there is known to be an issue) around the time of mating. It has not been shown to be beneficial to the dam, and there is a risk of side effects from the medication, and the dam could develop a resistant infection as a result.

Repeated courses of antibiotics also reduce the number of bacteria normally living on your dog. These form part of your dog’s natural defense against illness, so giving multiple courses of antibiotics can actually increase the risk of certain infections.

Historically, there has been some concern that ultrasound scans might damage developing puppies or cause them to be reabsorbed, but there is no evidence to suggest that this is the case. Scans are important to establish whether a dam is pregnant and to monitor the health of the puppies and should be done as recommended by your veterinarian.

What Should I Do If I Think My Dog Has Absorbed Puppies?

If you think your dam may be having problems during pregnancy, or if she is suffering from infertility, then you should speak to your veterinarian. Some of the conditions that cause puppy resorption can also be life-threatening to the mother, and you should not delay in getting her checked over.

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Canine fetal absorption occurs in more than 1 in 10 pregnancies, but it happens very early, and it’s possible you won’t even realize it has occurred. The best way to prevent it is to carefully plan breeding—you should choose the stud dog carefully, make sure your female dog is in the best health, and follow any vaccination and preventative schedules recommended by your veterinarian.

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Featured Image Credit: thirawatana phaisalratana, Shutterstock

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