When it comes to dealing with animal hoarding, you may be able to help by quoting the experts, especially animal-welfare organizations.
Someone who lives with 50 cats is, most likely, quite attached to them and doesn't want to give them up. On the other hand, they probably do care about their well-being. One way to get this type of hoarder to see the harm in their behavior is to provide reliable testimony to the health dangers faced by these animals. It's possible that even if your loved one rejects your assessment of the situation, he or she may consider the opinion of animal rights' proponents or veterinary organizations.
Use specific examples of why it's unsafe to have so many animals in one small space, not only for the animals but also for the person or people living with them. A hoarder probably feels a great sense of responsibility for these creatures, so try to provide real-world scenarios describing a few safe places where the animals could go.
Here, we get to another important part of helping a hoarder overcome the disorder: offering choices.