Experts are warning us to be on our guard for fluke this winter. With 1 in 5 cattle livers condemned at slaughter and as high as 60% in some places, vigilant control is paramount to animal welfare and farm profits.

Charlie Carslake from Molecare Veterinary Services warns owners of the clinical signs to be aware of, the life cycle and the control options available.

Fluke affects the liver, an organ which is central to numerous metabolic processes. Clinical signs include ill thrift, weight loss, bottle jaw, diarrhoea and anaemia. However, unsurprising for an organ as important as the liver, clinical signs are but the tip of the iceberg. Fluke infestation results in reduced weight gain, reduced fertility, reduced milk production and lower farm profits.

Unlike many parasites the life cycle of fluke is complicated and involves an intermediate host, a water snail. Snails are infected by eggs passed through the faeces of cattle and sheep. Infected snails produce hundreds of larvae and can infect any animal that is unfortunate enough to eat them. This can take between five weeks and a few months depending on temperature and moisture. Once ingested, significant damage is caused to the liver when the fluke larvae migrate from the intestines and through the liver in order to reach the bile ducts where, 10-12 weeks after being ingested they produce eggs. Eggs pass with the bile into the intestines and out onto pasture with the faeces. And so the cycle continues.

How successful fluke are at completing their lifecycle depends on certain factors. Some of these are out of our control but others such as environment and treatments can be within our hands.

Environment: Water snails need water and therefore fluke will only develop in wet ground. Unfortunately, they don’t need much and poaching by cattle can create an ideal temporary habitat. Boggy areas are permanent habitats. Avoid grazing on wet pasture or fence off areas to reduce the amount of fluke your livestock are exposed to.

Temperature: Out of our control but it is worth knowing that warmer winters are extending the time fluke can develop on pasture.

Treatment: Killing the fluke, ideally as early in its development as possible will halt the lifecycle in its tracks. However only one product, Triclabendazole, can kill all stages of fluke. It has to be given as a drench and has a long milk withdrawal.

Treatment options are complicated as numerous products are available to treat different stages of development with different withdrawals and are often found in combination with other worming products. Contact your vet to work out a parasite control plan that is suited to you.

Testing for fluke will help you decide whether you would benefit from treatment. Testing often involves taking a pooled faecal sample to look for eggs. This can only be done when fluke have matured into egg laying adults, normally from late autumn to spring. The rest of the year we can do an antigen test that detects immature fluke down to seven weeks of age. Milk and blood tests are also very useful in assessing fluke burden.