Hardware disease is generally caused by ingestion of sharply metallic objects. Swallowed metallic objects settle in the reticulum and probably irritate or penetrate the lining. Hardware disease can be prevented via the oral administration of a magnet. Hardware disease is most often in dairy cattle and very rarely reported in any other ruminants. Therefore, magnet for hardware disease prevention is naturally referred as cow magnet.

Appropriate feed management is certainly the prerequisite for hardware disease prevention. Cow magnet, also known as the rumen magnet, cow stomach magnet, or cattle magnet, is a veterinary medical device for the prevention of hardware disease. Cow magnet can attract metallic objects and avoid them from becoming lodged in the cow’s tissue. The original cow magnet is smoothed AlNiCo rod magnet, then today rumen magnet is more commonly several ferrite ring magnets attached to the stainless steel core. The latest design to contribute to increase effectiveness by a cage design, in which ferrite block magnet hold ferrous objects inside a protective plastic framework. In addition, another new design encase sintered Neodymium magnet inside a stainless steel case that similar like initial AlNiCo design.