How does Orwell present the lives of the animals in this extract from Animal Farm? “And even the miserable lives we lead are not allowed to reach their natural span. You young porkers who are sitting in front of me, every one of you will scream your lives out at the block within a year. To that horror we all must come — cows, pigs, hens, sheep, everyone. Even the horses and the dogs have no better fate. You, Boxer, the very day that those great muscles of yours lose their power, Jones will sell you to the knacker, who will cut your throat and boil you down for the foxhounds. As for the dogs, when they grow old and toothless, Jones ties a brick round their necks and drowns them in the nearest pond.”

Orwell describes the animals as exploited by people.
In this excerpt, Old Major is describing how human beings take advantage of animals on the farm.  Old Major tells the animals that humans are the only animals that consume without producing.  They take the animals and exploit and abuse them because they believe that the animals belong to them.
The basis of this paragraph is that the animals give the best of their lives to the humans, working hard for them, and then the humans have no appreciation.  When the animals have no use for them, they get rid of them in horrible ways.  All that awaits the animals is a life of suffering in service to man, and then a terrible death at last.
The pigs will die young, because their meat is valuable. They are examples of animals who are used for food.  The horse will be worked to death and then, since his body is valuable, it will be sold and fed to the dogs.  The dogs’ bodies are not valuable, so they will be drowned when they get too old.
Old Major suggests that the animals live their lives at the mercy of human beings.

"Is it not crystal clear, then, comrades, that all the evils of this life of ours spring from the tyranny of human beings? Only get rid of Man, and the produce of our labour would be our own. Almost overnight we could become rich and free. …” (Ch. 1) 

In this speech, Old Major also describes a dream in which the animals live on their own, without the tyranny of man.  The Animalism he describes is one of peace and harmony, where the animals take care of one another and never meet these cruel fates described by Old Major.  Animals will surely treat each other better than people.