When you own a dog, it's your responsibility not only to take care of the animal, but also to keep it from injuring people or damaging property. In urban and suburban areas, that usually means preventing it from biting someone. But in rural areas, it means keeping your dog from attacking or bothering neighbors' sheep, cows, horses, or other livestock. When that happens, there are two basic rules:
Many U.S. states have laws—which may go back over a hundred years—allowing farmers, ranchers, and others to kill dogs that are chasing, harassing, or attacking their livestock. Even without these statutes, however, it's long been a common-law rule that people may kill dogs when it's necessary to protect their property, including livestock. (See, for instance, Brauer v. English, 21 Mo. App. 490 (1886).)
A farmer or rancher usually doesn't have to wait until a dog has sunk its teeth into a calf or lamb. Most laws allow killing a dog that is chasing, "worrying," or preparing to attack livestock. However, simply running through a field where there are cows or sheep is probably not enough (see Trautman v. Day, 273 N.W.2d 712 (N.D. 1979)). Landowners usually don't have the right to kill dogs just for trespassing.
Also, the dog must be caught in the act of chasing or hurting livestock. In Texas, for instance, the law allows people to kill animals discovered in the act of injuring livestock or damaging crops, but the landowner must kill the predatory animals at the time of that discovery (Tex. Pen. Code § 42.092). As one court put it long ago, "It is not the dog's predatory habits, nor his past transgressions, nor his reputation, however bad, but the doctrine of self-defense, whether of person or property, that gives the right to kill." (State v. Smith, 72 S.E. 321 (N.C. 1911).)
The laws in some states clearly prohibit hunting down a predatory dog that has left the farmer's property. In Illinois, a court ruled that a sheep farmer wasn't protected under that state's law when he followed a dog back to its owner's home and shot it there, an hour after the dog had killed some of his sheep (People v. Pope, 383 N.E.2d 278 (Ill. Ct. App. 1978)).
In other states, however, courts have said the law allows farmers to pursue and kill predator dogs, even though the danger has passed. For example, the Kansas Supreme Court said that, "within a reasonable time" after the dog harassed livestock and fled the property, a farmer could chase and shoot it (McDonald v. Bauman, 433 P.2d 437 (Kan. 1967)). In Washington, the law specifically allows a livestock owner to kill a dog found running loose after a previous episode of harassing the livestock, as long as the dog's owner was notified about the earlier incident (Wash. Rev. Code § 16.08.020).
"Livestock" usually means only commercially valuable animals, not pets or wild animals. Some state laws list the kinds of animals protected. Others say only that a dog may be killed if it chases or attacks a "domestic animal." That term historically doesn't cover dogs and cats, and some states specifically exclude those pets from these laws (see Ohio Rev. Code § 955.28). Other states, however, specifically include dogs and cats in the definition of domestic animals (see 18 Penn. Cons. Stat. § 5561).
Depending on state law, that means someone who injures a dog that attacked another dog, a cat, or a wild animal in captivity may be found guilty of animal cruelty—and may be liable for the injury to the dog's owner. For instance, a Pennsylvania appellate court upheld a man's conviction for killing a dog that was harassing the man's deer. The state's animal cruelty law included an exception for killing dogs found in the act of destroying domestic animals, but "semiwild" deer in captivity weren't included in the law's definition of a domestic animal. (Com. v. Ingram, 926 A.2d 470 (Pa. Super. Ct. 2007).)
Whether a predatory dog got away or was shot, the livestock owner may sue the dog's owner for the damages it caused—the value of the dead livestock or other losses resulting from the injuries. In some states, like California, the dog owner may be liable for twice the amount of the actual damages (Cal. Food & Agric. Code § 31501).
Several states also have funds to reimburse farmers or ranchers who lose livestock to dogs. The animal owner must file a claim with the state, following procedures set out in the statute. In Illinois, for instance, once authorities have investigated and decided that a claim is valid, counties will pay damages to the owners once a year. Livestock owners may still sue the dog owners for damages, but the amount they received from the fund will be deducted from any court award in that suit. (510 Ill. Comp. Stat. Ann. §§ 5/19, 5/20.)
If you want to collect damages for the death or injury of your animal—whether livestock or a dog that might have been attacking other domestic animals—you may want to speak with an attorney experienced in animal law or personal injury law (even though it's legally a property damage case). Depending on amount of vet bills or the market value of killed animals, it may make sense to file a claim in small claims court, which offers a way to resolve smaller dispute without a lawyer.
If you're facing possible criminal charges for shooting a dog, you should contact a criminal defense attorney as soon as possible, in order to protect your rights.