I have an attachment disorder and I'm in therapy for it, but it's about people. I always have loved animals more than people, and poured my love on horses mainly. I've owned and trained horses since I was 11 yrs old. And I love and adore cats and kittens. Well, dogs, too. And Ring Tail Lemurs.

Anyway, I discovered that the great painful part of loving animals is that you have an Inner Child who can't reach you any way but to speak to you through the animals in your life. When you fully realize this and start giving to your Inner Child, the pain over animals becomes more manageable. Your Inner child has had to hide down in your subconscious and you have had to push her away because of very painful hurts in the past. She has found that you give love and attention to animals: so, she presents herself through them to feel some of the love.
With therapy, or even on your own, you can remind yourself of this when you feel the agony over an animal. After awhile the truth catches on. Not that you would love your actual animals any less, but that the edge is taken off as you understand where the extraordinary sensitivity is coming from. It sure did work for me.