I first found out about the beast through the book "The Natural History of the Unatural World" which despite seeming to have much fact to it, is a beautifully exciting book to look at. In the book, El Chupacabra is illustrated to be very Kangaroo-like.
Later when i read the description in the "A-Z of Cryptozoology" the desctiption says
I do not like the idea of it looking gray alien like. The creatures habbits and otherwise desctiption seems valid as just an unknown animal, which is far more believable than any 'gray alien.'
I sort of imagine a medium sized walibi, with no tail or notable ears and with an extended and upturned upper jaw with canines and a tongue designed for drinking the blood of other animals. I imagine it's nose being quite squashed out of the way and it's head to overall be very cat like with a arced nose and the head carries on to form a large brain cavity. I imagine most of it's body to have no hair and wrinkly skin like a hairless dog, but it has hair down it's back and the signature spine frill.