To be honest, Anu also likes dogs very much, she likes cats too. In her first life when she is a child she always wanted to have her own cat or dog, but as an orphan, she understands she will never get a dog or cat. As she doesn't get food for herself, so form where she will get the food for the dog.
And when she grows up, she struggles to live so she is not able to adopt any animal herself, in her next life she is too busy accompanying Mahendra that she never get the chance, so in this life, she wanted to take this responsibility.
Many people think that adopting a pet is quite a simple task, you just need to give them home, and feed them, But it is not the truth.