ANSWER:

The Prophet ﷺ told us that one of the reasons of the torment in the grave of people is because they didn’t purify themselves properly after urinating. This means that their prayers were invalid due to the impurity 

The same would apply to your family members who play with this dog as its impurity is far greater and more severe than the impurity of urine. 

If you told them this and they still don’t take that dog out, you have done your duty and you have no sin on you. You can stop visiting them and just call them. 

QUESTION: My brother and mother own a dog and won’t listen to me when I ask them to keep it away from me and some of our belongings. All of our belongings get covered in dog hair and najasah. It is to the point where they take the dog into all of the different cars and house we own and make them all filthy. Can I visit my mothers house?