How do I tell someone this constructively? Or not at all?

Ok I am house sitting for my sister and brother in law. She and me are super close. He doesn’t like me and never has. She had polio as a child (salk vaccine long story) anyway they have a super nice house. They have done the energy audit thing and it’s super insulated, when I came here I thought I was getting the flu. I bought some claritin and I feel better. There is dog hair everywhere, one dog has cushing’s disease and has to be let out every two to four hours,and medicated daily, which is why I am here. They have a house keeping service but their turkish rug is covered with dog hair. Everything is coated with dog hair. The one dog just vomited grass on the floor. My sister is on a huge amount of rx drugs. I think this house might be why she is sick. She is so busy she hasn’t time for reflection. I am talking narcotic painkillers. Should I broach this subject? She is going to have surgery again, when she gets back from holidays. I don’t know whether to bring it up or not.