I have had many dogs and I liked more of them sometimes I did my own family. How come I am let off lightly. If I go next door and shoot my neighbor’s dog or went down the whole subdivision kill all the dogs or cats. Shouldn’t I face a sever penalty. And mistreatment of them should carry the same weight as mistreatment to a minor?
Short legal answer: the difference is a category, not a degree of harm. Person or property.
Homicide statutes are defined by their victim. Murder is the unlawful killing of a human being, and a killing doesn’t get “upgraded” to murder when the victim isn’t a person, the same way a car can’t be assaulted. Animals aren’t legal persons, so killing someone’s pet lands either under animal-cruelty law or, more often, as damage to property, and what you owe tends to track the animal’s market value.
Slavery was the legal fiction that certain humans were property. It ended by moving those people into the “person” category (13th Amendment, then the 14th), not by softening the property rules. The category flipped.
Some groups now want a narrow version of that for animals. The Nonhuman Rights Project filed habeas corpus petitions for captive chimps (Tommy, Kiko) and, in 2022, for an elephant (Happy). The courts refused each time, holding the plaintiffs aren’t persons who can hold the writ. So the line has held, so far.
What did move without it: 46 of 50 US states now carry felony penalties for some forms of animal abuse, per Wikipedia’s summary. So “why not murder” is really “murder names a human victim” - the cruelty statutes are how that gap gets partially closed.