We believe that animals do go to heaven, because animals do have souls and spirits. God created them as living souls just like He did us (Genesis 1, 2).
You're not 'mental'; you're compassionate, which is exactly what God wants you to be. It's the other people who have the problem. Remember, that the person who lacks empathy for any part of God's creation, is showing that they are sociopathic.
Please take a look at the Bible section of our web site. We discuss these and other things in a lot more detail.
In the Love of the Lord,
Frank and Mary