Familiarize yourself with Iowa state laws regarding dogs.
I. C. A. § 351.1 - 43; I. C. A. § 162.20
These Iowa statutes comprise the state's dog laws. With regard to damage done by dogs and dog bites, the owner of a dog shall be liable to an injured party for all damages done by the dog, when the dog is caught in the action of worrying, maiming, or killing a domestic animal, or the dog is attacking or attempting to bite a person, except when the party damaged is doing an unlawful act, directly contributing to the injury. Further, the law states that it shall be the duty of the owner of any dog, cat or other animal which has bitten or attacked a person or any person having knowledge of such bite or attack to report this act to a local health or law enforcement official. The section also contains general rabies vaccination provisions and a prohibition on dogs running at large (results in impoundment).
I. C. A. § 351.27
This Iowas statute makes it lawful for any person to kill a dog, wearing a collar with a rabies vaccination tag attached, when the dog is caught in the act of worrying, chasing, maiming, or killing any domestic animal or fowl, or when such dog is attacking or attempting to bite a person.
Source: https://www.animallaw.info/statutes/topic/dangerous-dog
Keep your cats inside. Not an option for the horses. But frankly, horses are considered more valuable, and I wouldn't put it past these dogs to harass the horses.
