The animals certainly suffer as a result of the revolution, whether or not they deserve blame. And if the question is, "Do the animals deserve some blame for their eventual suffering?" I would say the answer is yes, they deserve some blame, but not all of the blame.
Napoleon's regime created the situation of exploitation which exists at the end of the story, but the animals all went along with that exploitation and failed to rebel or resist.
This question could be answered both ways:
Yes - The farm animals seem to be willfully blind to the pigs' manipulation, with the exception of Muriel the goat and Benjamin the donkey. They can't interepret the simplest signs of abuse and swallow everything Squealer says. Even the milk and apple arrangement goes down without a fight. The worst comes when Boxer is traded off with the knacker's in exchange for whiskey. Perhaps this was partially in reprisial for his having defended Snowball in his defense at the Battle of the Cowshed. Later on in the story, some animals even confess to crimes they didn't commit. They listen to silly stories from Moses the raven about Sugercandy Mountain instead of focusing on problems at hand. In a way, they asked for the kind of 'government' they got.
No - Is it really the animals' fault if their intelligence is so limited? They make an honest effort at learning to read since they know that literacy is somehow important. They try to "clean up their act" once Jones is gone, outlawing everything to do with the comportment of man. They work together to make their new community succeed without help from the outside. With the exception of Mollie and the cat, they all readily pitch in and do their part. Up until a certain point it seems as if all their effort will pay off. It is at the expulsion of Snowball and the destruction of the windmill that things start falling apart. They are victims of circumstance more than anything else.
Who would blame them? Maybe your question refers to responsibility rather than blame, and that is where I think the answer becomes important. If we keep Orwell's other writings in mind, we know that the ability to make the animals believe almost anything by manipulating both language and the past (think of what goes on at the Ministry of Truth in "1982") is what Orwell is warning us of. How close are we to the animals? They act according to their natures, accepting what they are told by their leaders. Can we/should we not expect more of ourselves?
To answer your question, I would not blame the animals for following their nature; insofar as we act like them, I would blame us for betraying ours.
Yes they are. As Orwell points out, revolutions have a way of turning out badly for the participants, as revolutions go.
No I do not blame the majority of the animals for letting themselves manipulated.
When seen from the viewpoint of animals we cannot deny that they were already oppressed by their human masters. The Vision presented by Old Major was definitely very attractive one, and as ordinary animal (or shall i say people) they had no means of making independent judgment about the practical problems of managing a system like that. Also though they were attracted by the idea, the finial decision of rebellion was in a way forced upon them by a sequence of events rather than executed in a planned way. As the story says:
Now, as it turned out, the Rebellion was achieved much earlier and more easily than anyone had expected.
With one accord, though nothing of the kind had been planned beforehand, they flung themselves upon their tormentors.
Thus animal were caught in an unfortunate sequence of events, which they had no means of farseeing. The animal deserve our sympathy rather than our blame for their misfortune.