Can you spot the difference in these two injunctions?
Exodus 23:4: “When you encounter your enemy’s ox or donkey wandering you must take it back to him.”
Exodus 23:5: “When you see the donkey of your enemy lying under its burden and wish to refrain from helping him, you must nonetheless raise it with him.”
In the first instance, you come across the animal of the person you hate. You must nonetheless return it, because you are otherwise colluding in depriving another person of what belongs to him. But in the second instance, you do not encounter the animal – you merely “see” it. You would have to go over, out of your way, to assist.
Why do you nonetheless have to take action? Because in the second instance the animal is suffering. It is crushed under the burden. The loathing you feel for your enemy is not to be transferred to the animal; rather you need to have compassion for its suffering. Judaism has an entire set of laws, “tsa’ar ba’alei hayim,” the requirement “to prevent the suffering of living creatures.”
As a vegetarian I take the suffering of animals who are cruelly slaughtered seriously. Kashrut is a way of eating meat that attempts to minimize pain to the animal. But whether you eat meat or not, you are part of a tradition that in small ways and large is concerned to lessen the pain of the world.