My 4 year old son has asthma, and my ex-wife has 7 cats in her house?

I have my kids on the weekend and they are with my ex during the week. Our 4 year old son is asthmatic and my ex is now up to 7 cats in her house and she has a dog also. Whenever my son sleeps at my house he never has an asthma attack, but I know he does when he is at her house. I keep telling her to get rid of them but she doesn't listen. On top of that, she smokes. Should i contact CPS? My divorce isn't final yet and I am scared she will withold my kids from me if I call CPS but I am worried for his health. Also, whenever they come to my house, they are all scratched up from the cats.