How to breed bullmastiffs

Updated July 20, 2017

Bullmastiffs are intelligent and powerful dogs, and if you have a healthy bullmastiff, you may be considering breeding it. People often mistakenly believe that dog breeding is an easy way to make money, but it's actually expensive, stressful and takes time and dedication. True lovers of bullmastiffs will only breed the best dogs. If you feel ready to handle this responsibility, these specific instructions are the best place to begin.

Wait until your dogs are at least 2 years old. This is the age where testing for health problems is most accurate since bullmastiffs do not physically mature until then. Two years is the safest age to begin breeding for your female's health and safety, since her body will be mature enough to handle pregnancy and the behavioural impact of reproducing.

Register your bullmastiffs with a purebred dog club like the Kennel Club. This can only be done if your dog's pedigree confirms that your bullmastiff, its parents and grandparents are all purebred.

Show your dogs at conformation competitions which are run through an area bullmastiff club. Here, judges will compare your dogs to the bullmastiff standard based on physical characteristics, personality, proportions, colour and more. Dogs earn "points" if they are good examples of the breed, and can earn titles and championship rankings. If your bullmastiff is not able to earn points, it isn't a good selection for breeding.

Have screening tests performed on your bullmastiff's elbows, hips and knees by your vet for problems. Bullmastiffs can carry genetic issues that affect their joints.

Have your bullmastiff's blood tested for a gene for progressive retinal atrophy through a veterinary eye association. PRA is an eye lens condition that causes blindness.

Have your vet perform cardiac exams on your dog. There are genetic heart conditions such as sub-aortic stenosis, which causes heart murmurs and can be inherited by your dog's offspring.

Have your bullmastiff screened by a vet for canine brucellosis, a bacterial infection that causes infertility and abortion in canines and can be passed during mating. This should be done once each month for six months before a mating occurs.

Keep track of your female's heat cycles. She will come into heat approximately every six months. During the second week of your dog's heat cycle, she will be fertile and accept mating.

Place your male and female bullmastiffs together in a supervised area once every other day during the next week to allow mating to occur. If your female bullmastiff acts aggressively, separate your dogs and try again another day.

Allow the dogs to mate at each visit. The dogs need to have a "tie" during mating, which is where the male bullmastiff's penis becomes stuck inside the female's vagina for as little as a few minutes or for up to an hour. This is a sign that a mating has taken place, but doesn't signify conception.

Take your female bullmastiff to the vet at three to four weeks following the mating. The vet will feel the female's abdomen or take radiographs to check for pregnancy. If no pregnancy is found, you'll need to repeat Steps 7 through 10 at your female's next heat cycle.


Health screening tests can become expensive, so be sure to have funds set aside for these important exams. Screening for problems prior to breeding is less expensive than caring for sick puppies. When the mating takes place, you should already have prospective homes lined up for your puppies. Be prepared to keep any puppies that do not find homes.


If your dog tests positive for any infections, genetic diseases or other problems, don't breed it. Breeding is a serious undertaking, and breeding sickly or poor-quality bullmastiffs can have a negative impact on the breed.

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