Facial eczema: the production thief you can’t always see

For every cow showing obvious signs of facial eczema, there may be many more carrying hidden liver damage.

Facial eczema is back on the radar as summer approaches, and this season could be one worth watching.

While many farmers associate facial eczema with peeling skin and sun-sensitive cows, those visible signs are often just the tip of the iceberg. The real issue is liver damage, and many affected animals never show obvious symptoms. DairyNZ estimates that for every clinical case of facial eczema, there can be around 10 animals carrying subclinical liver damage. Even without visible signs, that damage can affect milk production, performance and long-term animal health.

That hidden damage is what makes facial eczema such a costly disease. By the time animals show visible signs, the damage has already been done. There is no cure, making prevention the most effective way to protect stock and avoid production losses.

This season, farmers may also need to pay attention in areas where facial eczema hasn’t traditionally been front of mind. DairyNZ reports the fungus, which is responsible for producing toxic spores, is being found further south than historically recorded, a trend expected to continue as conditions become more favourable.

Risk is driven by warm, humid conditions that allow spores to develop in dead pasture litter. A few warm nights, some moisture and the right conditions can quickly increase risk, even if the season doesn’t feel particularly wet.

For many farmers, zinc remains the cornerstone of a facial eczema prevention programme. Zinc can be delivered through feed, drenches or boluses, but the key is ensuring animals receive a protective dose before spore counts rise. Research has shown many treated cows in New Zealand still don’t receive enough zinc to prevent liver damage and the production losses that follow.

Zinc boluses are widely regarded as one of the most reliable options because they deliver a consistent dose directly to the animal, unlike systems that rely on daily water intake. Once animals are protected, tools such as ZincCheck can help confirm zinc levels are high enough to provide preventative protection, rather than simply supplying zinc without reaching effective thresholds.

Whatever prevention strategy is used, success comes down to timing.

Protection needs to be in place before spore challenges occur, not after liver damage has already happened. Monitoring spore counts on your own farm remains critical, as risk can vary significantly between neighbouring properties and even between paddocks. It’s also important to remember that facial eczema isn’t just a milking herd issue. Youngstock are equally vulnerable to liver damage, and the impact can carry through to future productivity and lifetime performance.

The challenge with facial eczema is that it’s easy to underestimate. A handful of visible cases can mask a much larger issue within the herd, with the biggest losses often coming from animals showing no obvious signs at all.

As summer conditions begin to develop, now is the time to review prevention plans, monitor spore counts and make sure protection is in place before risk starts to climb.

Because when it comes to facial eczema, protecting liver health is also about protecting production. Prevention remains one of the most effective ways to reduce the hidden cost of the disease and support herd performance through the season.