Cattle are susceptible to hardware disease from ingesting foreign material
Cattle eat quickly, without sorting their feed. They often ingest foreign material, especially when eating hay or processed feed that may contain bits of wire or metal.
David Steffen of the Veterinary Diagnostic Center at University of Nebraska-Lincoln says the overwhelming majority of foreign objects are wire two to 5.5 inches long.
“If the pieces are shorter, they probably pass through the stomachs without causing a problem,” he says.
Ingesting foreign objects
Foreign material that doesn’t pass on through usually falls into the reticulum. Contractions of this stomach during digestion may push them through the stomach wall. The reticulum lies against the diaphragm.
“If the sharp object makes it through the diaphragm it may penetrate the pericardial sac around the heart,” he says.
Cows may ingest fence staples, barn nails, bits of wire or any other objects that find their way into the feed.
“This is why fathers yell at their sons and daughters to pick up nails and staples. I remember the staples sailing off, when we tried to drive them into old dry cedar posts,” says Steffen.
“People also use baling wire to patch things together, or tie panels to a fence. Sometimes the end of the wire is hanging there and cows may lick or chew on it.”
Old fence wire lying in a field, with hay grown up around it, may get chopped up by swather and baler, and end up in the hay. There may be nails, roofing tacks and other sharp metal objects around a barnyard or junk pile that cattle graze. In feedlots, metal pieces may come off the feed handling equipment and be mixed with the feed. There are also instances of small sharp rocks penetrating the stomach wall.
“Sometimes we find the offending object at necropsy and sometimes it’s so small it gets lost in the stomach contents and we don’t find it. Sometimes it gets passed on through after it causes damage that creates an infection,” he says.
It’s not always easy to diagnose a case of “hardware disease” because the signs are not very specific.
“If the cow has a localized abscess, the first thing you might see is that she goes off feed and looks a little dull. These signs could also indicate several other diseases. By the time she shows signs of heart failure, it’s too late,” says Steffen.
“Most of the time, the cow will be dying by the time this is diagnosed. If it’s a valuable cow, surgery may be performed to remove a rib and open up the pericardium so it can drain. Some of these cows can be saved, and then you can get them through the rest of their pregnancy and get the valuable calf,” he says.
Hardware problems can occur any time during the animal’s life.
“The biggest issue is just trying to keep wire and other metal objects out of the cows’ feed,” he says.
Solving the problem
“When we get animals here that have died from various reasons – cows that were given magnets earlier in life – we find all kinds of metal objects stuck to the magnet. We find metal filings and flakes that come off augers and feed wagons, and lots of small short wires.”
It’s hard to know how much the magnets help.
“Some people give a magnet when they see a cow that might be showing early signs of hardware. If a metal object has just started to poke into the wall, introducing infection, putting the magnet into the stomach might pull it back into the reticulum and keep it somewhere safe where it won’t penetrate through,” he says.
Once the wire goes all the way through the wall and starts a case of peritonitis, however, the cow is at risk for fatal infection.
“You don’t always find the wire or nail that did it in an exploratory surgery. There’s also a chance that it started the infection and then passed on out, but the infection is already there,” he explains.
Incidence of hardware disease
Dairy cattle tend to have a higher incidence of hardware disease because they are fed more processed feeds. Beef cattle on range pastures rarely ingest as much foreign material, but there can still be miscellaneous objects baled in hay or in supplemental feeds. Feedlot animals are also at risk.
Occasionally a non-metallic object – even a sharp rock – may penetrate the stomach lining and cause peritonitis or damage another organ such as the heart or liver.
For example, one rancher tells of a cow in late winter that suddenly showed signs of acute hardware disease and heart failure – with her back humped up, reluctance to move, trembling and staggering. She died quickly, and at necropsy the veterinarian discovered a small, flinty rock – about the shape and sharpness of an arrowhead – that had gone through the lining around the cow’s heart.
The day before she died, the herd had been moved to a different field, traveling across a driveway where hay had been spilled along the edge of the road. The cattle had gobbled up the hay, and apparently this cow had ingested a piece of sharp gravel with a mouthful of hay. A magnet would not have helped in this situation.
Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.