Did you watch a movie recently or look at anything that relates to the grotesque-ness of your dream? I have dreams similar to yours quite often. So often in fact I don't consider them to be nightmares anymore.
I have always had dreams where I am finding animals on the brink of them dying. It always seems to be "my pets" in my dreams or lack of responsibilities like I forgot I had all these birds and or rodents or puppies or cats. So I remember in my dream oh no I forgot to feed all these animals like for eons. And I come to them barely alive and trying to clean up and nurse them back to health.
One dream a few nights ago was a cat that wasn't mine. It was blind and eyes were sealed shut with crust. It seemed to have a different head than body because I noticed it's legs were broken too. I have always been an animal lover and advocate for animal rights so it's probably the reason for me.
If I ever dream of pets I've had that have died or still have they are always fine in my dreams. Last night I adopted a whole shelter of cats it seemed like...and a chicken that I couldn't find...

I think these dreams are somewhat normal, I read Lena Dunhams book..

and she has the same recurring dreams. She thinks it's a subconscious internal need to be well...maternal. Not sure about that but animals are spiritual creatures to me that are connected to the other side. I don't personally think your dream means anything bad sometimes with mine I think "how could someone do this to an innocent being with no voice" maybe you feel the same compassion? we all should
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Rather than love, than money, than fame, give me truth.
-Thoreau