The definition of a mixed marriage in many cases refers to the mixing of dogs and cats in the same household:

LuAnn Verbosky, off-site adoption manager for the Animal Rescue League of Western Pennsylvania in East Liberty, says that many cat-vs.-dog conflicts with couples are solved by challenging misconceptions about canines and felines. Some people think all cats are aloof and reclusive, for instance, while many cats, in fact, are very affectionate. Other people might think all dogs are hyperactive and overwhelming, while many are calm and mellow.

Usually, mixed-pet households work out fine, says Verbosky, who often sees happy couples come back to rave about their adoption of a cat or dog, after one person was reluctant.

The Pittsburgh Tribune-Review printed two very similar articles at http://www.pittsburghlive.com/x/pittsburghtrib/search/s_521987.html and http://www.pittsburghlive.com/x/pittsburghtrib/search/s_522082.html.