Is it permissible to keep dogs in a Muslim's house and to be extravagant with money in building a house for them?

It is not permissible to keep dogs in houses except for hunting or guarding dogs, and any excess beyond what is needed must be removed. It is not permissible to be extravagant in building houses for dogs, because extravagance is forbidden even in matters concerning humans, so how about dogs? The condition of needy Muslims should be remembered.