Wire in tyres possible threat to cattle

Duncan Bruce

Tyres used on the top of silage pits could pose a risk to cattle by causing Traumatic Reticuloperitonitis (TRP), which results from cattle eating metal and, occasionally, other sharp objects. These then go on to penetrate the reticulum (the first part of the cow’s stomach), causing infection and injury to the abdomen and other organs.

The main source of wire comes from disintegrated tyres, which is why it is important to check and dispose of any tyres with deterioration and take care to avoid getting any into the feeder wagon.

Previously, the main problem was fence wire and this has been improved by the addition of magnets and metal detectors to forage harvesters. Ash from bonfires may also contain metal fragments and these areas need to be fenced off.

Metal and other sharp pieces of the right size get stuck in the reticulum. The reticulum contracts in part of the cudding process and this pushes the wire through the reticular wall into the abdomen. Infection is introduced at the same time causing peritonitis. The wire(s) can migrate back and forth to the reticulum or into the liver, spleen, chest cavity or the heart. A number of these may simply cause a brief peritonitis from which the animal apparently makes a reasonable recovery, with the adhesions only noted in the abattoir when the animal is slaughtered.

In most cows, the initial signs are an immediate sharp milk drop, poor appetite, a mildly raised temperature and absent or reduced rumen movements. They can have a slight bloat and a stiffish gait.

Vet diagnosis and successful treatment in the first 48hrs can usually be straight-forward. Most of these signs will improve over a couple of days. Some cows can make a complete recovery even without treatment, but a significant number will go on to have a grumbling peritonitis with abscesses, poor milk yield and loss of condition. Some will develop fatal infections. This can be rapid when the wire passes into the heart itself.

Initial treatment for individual cows typically involves the introduction of a magnet, designed to lodge in the reticulum. This is administered with a course of antibiotics. Chronic cases are more difficult to treat and longstanding cases are often unresponsive.