I think that there are quite a few contenders for this actually. Rabbits are definitely up there, as they are cheap to come by, and are bought for children who quickly get bored. Also fish, as others have mentioned, because people don't even see them as living beings half the time; they just buy them as a decoration for the room :roll: Also small furries like hamsters/ gerbils because people don't think that they are worth spending money on, and horses, because they are just abandoned in fields and forgotten about, as they are deemed to 'too expensive'.
I would also argue that any animal that is currently 'fashionable' is in grave danger of being heavily neglected, so for me at the moment, I would argue that chickens are also up there with the other animals. People buy eggs to hatch or tiny chicks because they are cute, and don't allow for the amount of roosters that will hatch. These are either given away for free on freeads (where they can be used for anything from **** fighting to dog bait), have their necks snapped by people who have no idea what they are doing (so I imagine that it is pretty brutal and painful) or are just dumped. Hens don't get a much better life as many are gotten rid of as soon as they stop laying, or are again dispatched. People don't know how to look after them so they get ill and won't take them to the vet, because after all they are 'just' chickens :roll::evil:
The other night, on an ex-battery hen rescue group I am a member of, a man was casually talking about how he came home to find that his dog was 'playing with the chickens'. The dog had severely wounded one of his hens, who had bits of skin and muscle hanging off her. He was asking for advise on what to do next as he had already 'glued her back together' and wasn't sure what he should do now
:evil:
No pain relief, no cleaning or flushing out the wounds and no knowledge of what he was doing. He just took it upon himself to grab bits of skin and superglue them back together. When he was asked why he did not bring her to the vet he said that there were 'none open'. It was Good Friday. There were vets open but they were emergency vets and he didn't want to spend that money on her. I ask the question, as I did to him (and got no response) would you have done the same thing if it was a cat or dog in that situation? No, I think not. So why should any other animal be different?! It doesn't matter what your pet is, you have a duty of care to it and it should go to the vets if need be (even to just be PTS if you can't afford very expensive treatment).