Introducing a new animal into your home always requires planning and patience. When introducing a Bullmastiff to a kitten, there are several things to consider and for which to plan. The most important thing to keep in mind is that Bullmastiffs are large dogs bred to protect their home and family. According to the American Bullmastiff Association, these dogs do not tolerate other dogs well, but may do okay with a cat. You want to make the introductions slowly, over a period of several days. Ideally, your Bullmastiff will a be well-trained adult or a puppy in training.
Bring the kitten home in a crate and place it in a separate room that can be closed off from the rest of your house. Allow the kitten to come out of the crate into the room on its own. Place food, water and a litter box in the room and keep the cat there for two to three days to give it time to familiarize itself with its new surroundings.2
Allow your Bullmastiff to meet the kitten through the room door. Introduce the kitten and the Bullmastiff to each others' scents prior to a face-to-face meeting, so the kitten is not a surprise.3
Place your Bullmastiff outdoors and let the kitten out of the room. Give the kitten time to explore the house without the dog present. Allow the kitten to familiarize itself with your home, which includes locating safe places to hide. Give the kitten an hour or two alone.4
Use a regular dog leash to restrain your Bullmastiff when introducing it to your kitten for the first time. Instruct your dog to sit or lay down. Let the kitten approach the dog on its own.5
Repeat the introduction using the leash as many times as necessary for both animals to become familiar with each other. Remove the leash for the first time, but do not leave the dog and kitten unsupervised.