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Unwanted Mating/Pregnancy

Unwanted mating or pregnancy, also known as misalliance or mesalliance, occurs when a female dog is in heat and has a mating that the owner does not desire. Dogs are quite fertile, and eight out of ten females will become pregnant following successful mating. There are already a lot of stray dogs in the world, so having an unplanned litter of puppies is a significant commitment. It can be even tougher to find suitable homes for them all. A veterinarian should be contacted as soon as a bitch has been inadvertently mated; the pregnancy might be prevented.

What predisposes dogs to unwanted pregnancies?


Unneutered oestrus females permitted to roam or come into contact with intact males are more likely to have unwanted pregnancies. Due to their high fertility, dogs have an over 80% probability of becoming pregnant after mating. Misalliance then promotes an improper male to breed the bitch.

How does one tell if a dog is pregnant?


A pregnant Labrador Retriever
A pregnant Labrador Retriever

There is always a high possibility that a dog may be pregnant if a male dog mounts her while she is in season. Within a few days of mating, some dogs may exhibit unusual behaviour; however, this can happen whether or not the female is genuinely pregnant. It is quite challenging to determine whether the dog is pregnant at first because there won't be any physical changes until she is about 40 days along, at which point there might be some belly swelling. However, first-time mothers and those carrying a few puppies might not experience any change in shape before the delivery of the puppies. Around 30 days after mating, the nipples and mammary glands may swell, although dogs may also experience this condition whether or not they are pregnant. If a litter of puppies is not required, it is advisable to take the dog to the vet before it becomes clear that she is pregnant.

How does a veterinarian know if a dog is pregnant?


The veterinarian can diagnose pregnancy in a variety of ways. These include:-

  1. Transabdominal palpation for pregnancy diagnosis at 25-35 days after (suspected) mating.

  2. Taking a smear from the dog's vagina (vaginal cytology) can help the veterinarian estimate the dog's cycle stage by looking at the sort of cells detected and evaluating whether or not the dog might get pregnant at that time if the alleged mating occurred within the last three days.

A smear slide on a microscope stand
A smear slide on a microscope stand

In most cases, if mating has just occurred, sperms can be seen in a smear. Treatment is frequently made available prior to the pregnancy becoming established.

3. From days 21 to 25 following mating, a dog pregnancy test that evaluates blood hormone levels can also be used to confirm pregnancy.

Illustration showing  Ovarian Cycle and Hormone level s
Illustration showing Ovarian Cycle and Hormone levels

4. Early pregnancy can also be determined via ultrasound between days 20 and 22 after the LH (Luteinizing hormone) surge. It is also possible to start treating patients at this time.

Ultrasound being performed in a pregnant dog
Ultrasound being performed in a pregnant dog

How can dogs be stopped from getting pregnant?


The standard procedure to stop an unintended pregnancy in a female dog is to neuter (Ovariohysterectomy). her. Even if the dog has already been mated and was scheduled to be neutered, the surgery can still be carried on as long as it is done soon after mating because at this point the procedure is not as problematic. A veterinarian can administer an injection to halt the pregnancy if the dog was accidentally mated and neutering wasn't the plan, for instance, if a litter of puppies is later needed. When the injection is given within the first three weeks of mating, it works best.

Only when the hormone progesterone is present does pregnancy in dogs continue. An injection of a progesterone-blocking medication ends the pregnancy if administered between 0 and 45 days after mating (best if given in the first 3 weeks). Two doses are administered, separated by a day. In the initial few days following mating, the medication can stop implantation, ensuring that no pregnancy ever develops. If it is administered later, abortion occurs (about 3 days after injection), leading to the expulsion of foetuses. About 28 days after mating, a vet should examine the dog to make sure the pregnancy is terminated.

Confinement of breeding females when they are in heat (oestrous) is another way to stop female dogs from having unintended pregnancies.

Are there any complications with the anti-pregnancy injections?


Unfortunately, the injection can cause a number of unfavourable side effects, including depression, appetite loss, and a discharge that may be clear or brown from the vagina. Injections administered late in pregnancy result in abortion, and the dog may exhibit labour symptoms. Not all of the puppies are always expelled, in which case more therapy may be required. Because of this, it's crucial to have a dog checked by a vet again following treatment to ensure all the puppies have been taken out. Care must be required to prevent unintended mating in dogs who have received anti-progesterone injections because they may return to season fast (1-3 months later).



Unwanted pregnancies in dogs are a great concern for pet owners. If puppies are not needed, it is important that steps are taken to prevent pregnancy. One option is to have the bitch spayed (for females) or the dog neutered (for males). These are surgical procedures that prevent dogs from being able to reproduce. They are generally safe and effective, and they also have other benefits such as reducing the risk of certain types of cancers and eliminating unwanted behaviours like marking territory.

If the dog has already become pregnant and she is not allowed to have the puppies, the pregnancy can be terminated through a surgical procedure called an abortion. This is typically only done in the early stages of pregnancy and should be done by a veterinarian. It is important to note that abortion is a controversial topic, and options need to be carefully considered before a decision is made.

If spaying or neutering your dog or terminating the pregnancy is not part of the plan, it is important to be prepared for the responsibilities of caring for a litter of puppies. This includes finding homes for the puppies, providing proper nutrition and medical care, and training and socializing the puppies.



McLauchlan, G., & Ramsey, I. (2008). Update on pregnancy termination in the bitch. UK Vet Companion Animal, 13(9), 25-28.

Whitehead, M. L. (2008). Risk of pyometra in bitches treated for mismating with low doses of oestradiol benzoate. Veterinary Record, 162(23), 746-749.

Tsutsui, T., Mizutani, W., Hori, T., Oishi, K., Sugi, Y., & Kawakami, E. (2006). Estradiol benzoate for preventing pregnancy in mismated dogs. Theriogenology, 66(6-7), 1568-1572.

Sarkar, D., Krisnaswamy, A., Sudha, G., & Teja, A. (2021). A study upon the incidences of mismating in dog and clients desideratum for solution.

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