Is prayer valid in a house where a dog is kept for entertainment, and what is the ruling on keeping dogs for purposes other than guarding?

It is not permissible to keep a dog except for hunting or guarding. There is no harm in praying in a house where there is a dog, unless you are certain of the impurity of the place where you pray, or this becomes highly probable in your estimation. In such a case, it is obligatory to purify it or to pray in a place free from impurity.