Meal not metal

Most farmers will have had a cow diagnosed with hardware disease at some stage in their career.

The areas where metal commonly travels to once a cow ingests it.

By Lisa Whitfield

Hardware disease must be one of the most practically named animal diseases.

I remember hearing about it when I was in vet school and thinking to myself – how interesting to have a disease which is basically entirely man-made – it can’t be blamed on bacteria, viruses, the weather or the mud, it is solely a human-made disease.

Most farmers will have had a cow diagnosed with hardware disease at some stage in their career. While it is not something that I see every day, most people have a story to tell of the cow they had which died of it.

The worst case I have been involved with was when a piece of fencing wire was accidentally chopped into silage, and the farm lost eight cows over just a few weeks.

The type of metal objects commonly found onfarm which can be picked up by cows can be collected by a rumen

In one of those cows which I did a postmortem, a 1 inch length of fencing wire had lodged in the space between her liver and rumen, and many litres of infected fluid had formed into an abscess.

Hardware disease occurs when a cow accidentally eats a sharp, often metal, object such as a nail, fencing staples, or offcuts of fencing wire.

The reticulum is the sorting compartment of the cows stomachs, where large food particles are separated and sorted from fine particles.

Dense objects such as metal can become lodged in the reticulum, and may puncture the stomach wall.

Once this has occurred, the object can track through into other parts of the body. Bacteria from the gut will also track with the object, and major infection will form leading to sickness and often the death of the cow.

Predilection sites for infection are the abdominal cavity, liver and through the diaphragm into the lungs and the heart – all of the structures which are in close proximity to the reticulum.

It is thought that anything which increases abdominal pressure, such as pregnancy, calving and riding cows during oestrus, can increase the risk of metal piercing through the reticulum wall.


The treatment for hardware disease is a long course of antibiotics, anti-inflammatories, and giving her a rumen magnet.

Unfortunately for many cows, they are found when the disease is at a stage where the damage is already done, the infection is overwhelming and the cow is not likely to survive and thrive.

Did you know that a rumen magnet is not only part of the treatment for hardware disease, but can also be a very effective preventative? Giving a rumen magnet to each cow in your herd reduces the risk of them getting sick in the first place.

The humble rumen magnet is a very low-cost item. Would you spend $3.35 on a cow, once in her lifetime, to reduce the risk of her getting hardware disease? This is less than 0.001% of the average cow’s production per season – less than 0.5kg milk solids.

Administering a magnet to a cow only has to be done once as the magnet lodges in the rumen or reticulum and stays there as it is too big to pass further through the cow. Rumen magnets are given using an oral bolus applicator.

The magnet attracts stray metal that she may accidentally ingest. With the level of concentrates going through mixer wagons, as well as the many kilometres of fencing wire and thousands of staples used around our farms, the risk of a cow being exposed to stray metal fragments in her day-to-day life is real enough.

Practically, the idea of bolusing your whole herd may seem like a nightmare.

An alternative to doing the whole herd at once is to bolus some of your herd each year, and gradually build up the numbers. For example, you may bolus your replacement heifers when they are tagged each season.

Consider the value of your cows and the risk of them consuming stray metal fragments – for the cost of a magnet, why wouldn’t you do it?

  • Lisa Whitfield is a Manawatu veterinarian with Lisa Whitfield Farm Vet Services, Palmerston North.