Mastiffs are one of the largest breeds recognized by the American Kennel Club. Because of this, knowing when a mastiff is pregnant can be difficult, due to their already large size. Pregnancy symptoms tend to be common throughout different dog breeds, but taking your Mastiff to a vet is the surest way to learn if the dog is pregnant. Typical pregnancy signs and symptoms won't appear for at least two weeks after conception, so if you have bred a dog, wait a few days or even weeks before looking for pregnancy signs or taking the dog to a vet for confirmation.
When a dog is pregnant, her nipples will swell. Often they will darken in addition to enlarging. When the pregnancy is close to being carried to term, the dog's nipples may start to lactate.
Some expectant mothers will experience morning sickness for a few days just as a pregnant human will. This is caused by the uterus stretching and changes occurring internally in the Mastiff, and will pass. Many owners may not notice morning sickness, as all dogs vomit periodically even when not pregnant.
Change in Appetite
A Mastiff is known for being a large dog and having an equally large appetite. Because of this, noticing a change in appetite may be difficult. Regardless, dogs developing puppies inside can experience a noticeable increase in appetite that grows the closer the dog comes to labor.
A dog's stomach can grow 20 to 50 percent larger depending on the size and number of puppies she is expecting. Because of a mastiff's large size, a growing belly can sometimes go unnoticed if only a few puppies are growing. If you take the dog to the vet, she can use an ultrasound to listen for heart beats inside the dog's belly to confirm if the dog is pregnant.