The safest introductions
between cats and dogs are when they are young kittens and puppies being adopted
and introduced to each other at the same time. This allows them the time to
become socialized with one another and to bond together. It goes without saying
that especially at the beginning, 100% supervision is required when the 2 pets
are together. You want to especially gauge the puppy's reaction to the cat and
make sure that the puppy is not playing too roughly with the cat. If it is, the
cat will likely run to a safe place in the house. Make sure your cat has a safe
place it can go to relax away from the dog. If you catch puppy playing too
roughly, give your puppy a firm "NO" and separate the dog from the cat. Until
you are 100% sure that the puppy and the kitten can get along safely, NEVER
leave the 2 of them alone together. It should also be stated that if or when the
dog becomes tolerant of the family cat, it may still chase/hunt/kill other
non-family cats. It really depends on the particular dog.

More often then not though,
households already have an existing pet and then people get a new cat or a dog.
In this case, the resident pet should be given a greater amount of
consideration. After all, the resident pet's territory is being ‘invaded' by
another species and this invasion is stressful for the resident pet. To ease
this transition, the resident pet should get a chance to smell the new pet
BEFORE it enters the household. This can easily be done by wiping the new pet
with a towel or cloth that will absorb its smell. Then take that towel or cloth
and allow the resident pet to smell it and leave it where it sleeps or hangs
out. Do the exact same thing to the new pet; let it smell a towel or cloth of
the resident pet before it comes to your home.

In terms of the actual
first time introduction many people recommend that the pets smell each other
from opposite sides of a closed door and this makes good sense. After this, let
them meet face to face while the cat is in a carrier and the dog is on a leash
under your control. If this goes well, open the cage and let the cat out while
still holding the dog on the leash. Let them meet each other face to face but be
aware of any signs of aggression especially from the dog. Use a firm "NO" and a
light tug on the leash if the dog shows any signs of aggression and then
separate the two. Try again later.

These are only a few basic
tips and you should research this topic in depth before you get any new pet of a
different species. It goes without saying that some dog breeds have much
stronger predatory drives toward cats than other breeds. Many terriers are known
not to get along with cats since they were originally bred to hunt down rodents
and rabbits. Many sporting dogs like Weimaraners and Greyhounds are also bad
with cats, as are some pit bulls. Even though particular members of these breeds
may be okay with cats, they (and other breeds not mentioned here) are riskier
breeds so please research this before the new pet comes home. A professional
dog-trainer and your veterinarian are good sources of information if you need
help with this issue. As the final note of the article, please NEVER leave these
pets alone unsupervised until you are 100% sure that the dog has no predatory
response toward the cat.