How Long Are English Mastiffs Pregnant? A Guide to English Mastiff Pregnancy

Normally, the gestation period for a pregnant English Mastiff lasts for approximately 63 days. This can even go for as long as 68 days considering that this dog breed is a massive one. Understandably, smaller dogs typically give birth much earlier. 

Photo from: airsnarp (IG)

The old English Mastiff is known to be calm, loyal, affectionate, and brave. All these are among the many reasons which prompt several English Mastiff owners to constantly breed their dogs. While pregnancy in dogs is a natural process, still, every owner must know how to properly deal with such a case.

Learn important facts such as how to know if your Mastiff is pregnant, ways to take care of her the entire gestation period, and birth emergencies you need to be prepared for. Let’s dig in!

How Many Puppies Can an English Mastiff Give Birth To?

It is always a possibility that your English Mastiff will give birth to only one puppy in a pregnancy. Reports, however, have shown that she can produce up to 16 puppies and 8 is the average number. The size of the litter largely depends on the age of the dam. Generally, the older she is, the smaller her litter size will be. 

That would mean that if you have had your English Mastiff mated at a young age, you, as a breeder, can expect that she will deliver several puppies once she labors. Timing is everything when it comes to breeding. Ideally, a female Mastiff can be bred once she’s 22 months old since she’s already capable and mature enough to give birth at that age. 

However, breeders highly recommend not to have her mated with a stud during her first few heats. For several decades, many breeders have tried to make this mistake and the usual result is disastrous. Often, young English Mastiff mothers end up having the following:

  • Bad behavior
  • Aggression
  • Possibility of passing on the bad genes to offspring
  • Physically and mentally incapable to raise her puppies

Signs That Your Dog Is Pregnant

Although going to the vet can 100 percent determine if your English Mastiff is pregnant, know that there are various telltale signs you can watch for which would tell you that she is. You will notice enough physical and behavioral changes that would make you wonder what is going on with your dog. 

These signs may include:

  • Increase in appetite. A pregnant English Mastiff will want to eat more than usual. Her diet will have to be one and a half times more to support the growing babies inside her womb. 

Remember, she’s no longer one individual but rather, several puppies are waiting to receive proper nutrition. Her meals need to be upgraded appropriately for gestating mothers so all her babies would be born healthy and without defects.

  • Change in nipple size. Compared to flat areolas you were used to seeing from your dog, these will gradually turn larger and discolored once she’s affirmatively pregnant. Such changes indicate an increase in blood flow. The closer she gets to her due date, the more possible it is that milk will leak out of her nipples.
  • Swollen belly. This is a great indicator that your Mastiff is pregnant. The intensity of her belly’s swelling will grow as days and weeks pass by. At the last two weeks of her pregnancy, you’ll notice her pups moving inside her belly.
  • Weight gain. Added weight usually becomes noticeable after 21 days into pregnancy. This will depend on how big the size of the litter she’s going to give birth to. Since she’s pregnant, it is understandable that she will be heavier than before due to the growing puppies in the womb.
  • Affectionate. English Mastiffs are ideally affectionate, but a pregnant one is more likely to be more clingy and loving. Her hormone levels will change hence the shift in her mood toward you. This remains to be a case-to-case basis, however, since some pregnant Mastiffs can also be quiet, moody, or withdrawn. 
  • Irritability. This shows often when she nears her due date. Her nesting behavior and preference for solitude will take place. She will also be more and more restless before her labor day.

On another note, be aware that your dog can experience some of the signs listed above and end up having a false pregnancy. To make sure on whether your Mastiff is indeed pregnant or not, bringing her to the vet will give you a more accurate answer.

Ways to Find Out if Your English Mastiff Is Pregnant

Unlike humans, your English Mastiff certainly can’t go to a pharmacy store to purchase a pregnancy kit. Instead, she would need a helping hand from her owner so she can undergo different tests that will confirm that she’s carrying little pups inside of her. 

  1. Abdominal Palpation

This can be taken 28 to 30 days after ovulation. Preferably, this kind of test is suitable for cooperative female English Mastiffs. Nervous dogs will usually have tense abdomens and the uterus can be hardly felt. Moreover, considering how big the Mastiff is, it can be quite a challenge to test if she’s pregnant this way.

  1. Relaxin Canine Pregnancy Test

This test can be done 21 to 28 days after your Mastiff is mated. The pregnancy test will determine if the dog produces the relaxin hormone which is primarily from the canine placenta. The only drawback is that such a method can draw a negative result. This needs to be taken with other tests or retaken 7 or 10 days after you’ve conducted this.

  1. Ultrasound

Ultrasound is the common method breeders have their Mastiffs undergo. A dog suspected to be pregnant can be taken to the vet for this test 20 to 30 days post-breeding. Although this is not an accurate tool to count the puppies, it certainly can detect heartbeats from the womb.

  1. Radiographic Diagnosis

Ideally, radiographic diagnosis of pregnancy should be done 55 days after first breeding so there would be an accurate count of the number of puppies in your English Mastiff’s belly. Yet, it is still possible to do it 42 to 50 days after mating.

How to Take Care of a Pregnant English Mastiff

Once it has been determined and well-tested out that your English Mastiff is pregnant, the next steps you’d take would be highly crucial. Our pets are our responsibility and more care should be granted especially knowing that more fur buddies are on the way.

There are a few steps you should take to guarantee that your pregnant pet is healthy.

Diet & Nutrition

It is your priority to make sure that your pregnant bitch gets all the nutrition she needs from the right diet. Talking to your vet regarding her dog food consumption is recommended so you know you’re either doing the right thing or some changes need to be done. Usually, it is not advised to add more cups of food in her bowl in the first 2/3 of her pregnancy as this can be harmful.

Talk with the expert regarding what type of food she’d need, how much, and how often she should be fed so her health is guaranteed. 

Vet Visits

It is no surprise that regularly visiting your local vet will greatly contribute to the well-being of your pregnant English Mastiff. He can check the progress of her pregnancy as well as suggest certain methods that will prove beneficial to her and her future puppies such as deworming her on the 40th day of gestation and under 14 days post whelping to decrease the amount of hookworm and roundworms that might infect her newborn pups.

You would also be able to discuss whether there would be a possibility that your dog will undergo a cesarean section or natural birth. Emergencies will also be talked about and future planning such as spaying your dog for good in case she got pregnant by accident.


Having your English Mastiff exercise arduously in her first two weeks of gestation is a no-no according to some vets. Limit it to other activities that do not require extreme effort to avoid pregnancy or birth complications. The same things should apply the moment she’s in her final trimester. Short walks are mostly enough for a pregnant bitch.

Watch Out for Signs of Labor

As the due date nears, certain signs will be exhibited by your pregnant English Mastiff such as avoiding to eat a few days before her labor. She’ll also start nesting, so providing her a whelping box will aid her in her reclusive behavior.

Usually, an English Mastiff will pant heavily indicating that she’s about to give birth at any moment. Abdominal contractions will start showing and a puppy may be delivered at the first hour. All of them are covered in a membrane that is either licked off by the mother. 

In some cases, you have to do this yourself so the pup can breathe. Clean him with a towel and rub him until you hear him cry. The umbilical cord that’s still connected to every pup needs to be cut off and tied an inch from the belly. The abdomen should then be lathered with iodine to lower the risk of infection.

During the process, don’t forget to give the mother some fresh water. Once all pups are born and clean, place them along the mother’s belly and make sure everyone is nursing.

Whelping Care Supplies to Buy

The arrival of newborn puppies needs intensive preparation. Of course, even the mother would need certain things for her entire gestation period. To make it more convenient for you, we have listed items your pregnant English Mastiff and her puppies would need.

  • A whelping box
  • Newspapers to line for the whelping box
  • Clean and dry towels for the puppies
  • Sterilized scissors to cut the cord
  • Clean and unwaxed dental floss to tie the umbilical cord
  • Iodine (Betadine)
  • Bulb syringe to clean puppy’s nose and mouth

Should there be any complications, having your vet’s phone number will prove helpful and convenient. 

Some complications you should be aware of are:

  • Pups aren’t nursing.
  • Your pregnant English Mastiff shows no signs of whelping on her due date.
  • All of the placentas are not delivered.
  • Trembling, collapsing, and shivering signs from your dog.
  • Strong abdominal contractions for an hour, but no puppy is delivered.
  • Contractions are shown for two hours but the first puppy is still not delivered.

Pregnancy doesn’t have to be distressing for your dog. The more knowledgeable you are about it, the easier it is for you to aid your English Mastiff. Be prepared and communicative with your vet for the welfare of your pet and her pups. Once all are delivered safely, ensure that they grow up socialized, healthy, and end up in loving families.