The default position in the law is that a child benefits from having a relationship with both parents. But the judge will consider any factor that tends to show that it's not in the best interests of the child to live with a particular parent, or for visits to be at an outside location rather than the home. Since it is legal to have pit bulls or Rottweiler in a home, it's not necessarily enough to say "He has these dogs." He's allowed to have them, and there isn't any law about having dogs and children in the same house. But she can describe what she's seen, express her concerns, and note any interactions that she's seen. She can also request that he be ordered to keep the dogs outside or crated when the child is with him so they're not roaming the house free, at least until the child is a bit older. Then, if he doesn't do it, he's in contempt of court (and she can take pictures to prove it).
She could also request that he be required to take the dogs to obedience training and provide evidence of having done so, which might help her feel better about having the child in his care.
They could also request that a guardian ad litem be appointed. That's a third party who comes out and looks at the home and would interact with the dogs and determine whether the home is safe for the dogs. It's a tough situation when you have a dog owner saying "My dogs aren't violent" and the other parent saying "I'm afraid of these dogs." It could help to have a third party do an evaluation on whether the dogs are dangerous.
If she can list other factors that show why the father shouldn't be allowed to keep the child overnight, that can also help. The judge is required to look at all of the facts of the case, and won't always decide a case based on a single issue. The more reasons she can give him to agree with her, the better.
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