With cattle being housed, parasite treatment comes to the fore. However, a good overall treatment plan should have been in place long before cattle are housed. With strong grass supplies in recent weeks, and good grazing conditions, many farmers kept stock out for longer than usual.

Where regular and adequate dosing did not take place for weanlings, some farmers reported cases of pneumonia, with the sharp change in temperatures and weather.

In addition, the presence of lungworms can allow bacteria and viruses to attack the calf, which often results in pneumonia. Bucket-reared calves are at most risk due to their grazing management over the summer months and the possibility of them encountering larger worm numbers.

For farmers who still have calves out and are considering dosing them, it is advised that it takes place at least two weeks prior to housing or weaning to help reduce stress.

If cattle are showing signs of severe lungworm burdens, then treatment is essential. However, a close eye should be kept on these cattle after treatment and stress should be kept to a minimum.

There are three active ingredients which can kill lungworms or hoose. These are benzimidazoles, endectocides and levamisoles. The method of treatment may influence the active ingredient used.

Lice

Lice affect all cattle, especially during the winter period. Signs of lice activity are cattle scratching and/or licking, poor coats, excess hair loss and, in some cases, anaemia.

There are two types of lice that affect cattle – biting and suckling lice. One thing that farmers need to be aware of is that not all products that will kill suckling lice will kill biting lice. Pyrethroids and externally applied endectocides are the only two active ingredients that will kill both biting and suckling lice and mange mites.

Timing of treatment is crucial. When animals are in close proximity, lice can transfer quickly and easily from one animal to another. Lice live for just over 34 days, so fast replication can be an issue.

Treatment will only kill hatched lice, not the eggs. For that reason, the need for secondary treatment will depend on the number of eggs laid and the severity of the problem.

It is advised that animals are treated for lice at housing to keep them under control. Where they are not treated at housing, more severe issues can occur in November and December as lice populations grow quickly.

Identify the problem

The most effective way of identifying a lungworm problem is by seeing symptoms in affected stock. Lice issues will be seen through the presence of scratching cattle, excessive licking, etc.

However, fluke may not be as easy to identify, as when acute cases are present, there may be a lot of damage done to livers. When doing faecal egg counts, it is advisable to take faecal samples from approximately 10 animals and send them for analysis within 48 hours. These results, combined with the symptoms, will give a clearer picture of the level of parasitic challenge facing the cattle.

However, where large worm/fluke challenges occur quickly, the animal may be heavily burdened and showing clinical signs without actually having a high faecal egg count. In these cases, where symptoms are evident, quick action should be taken to dose affected stock.

Fluke

Once analysis shows the presence of liver fluke, then action needs to be taken to ensure cattle remain thriving during the winter months. Apart from depressed weight gains, other symptoms of liver fluke are oedema (bottle jaw), anaemia, poor coat condition or appetite.

Where there is a severe fluke issue, a two-dose strategy may be adopted. This is where cattle are dosed at housing and again eight weeks later, but this depends on the product used.

Table 1 shows the various active ingredients that will kill liver fluke and the types of fluke they will kill. Where there is a lower level of fluke activity, then many farmers will wait until cattle are housed approximately six to eight weeks.

At this stage, most of the fluke in the animal will be mature and a wider variety of products can be used. Also, products can be used that kill immature and mature fluke. Table 1 shows the efficacy of the various products against early immature, immature and mature liver fluke. All of these products are 80% to 99% active for mature liver fluke where cattle have been housed for over three months.

Products containing oxyclozanide are effective at killing both rumen and liver fluke, but only mature stages of liver fluke and will not kill 100% of the fluke in the animal. Triclabendazole-based doses are the only products that can kill early immature, immature and adult liver fluke with a 90% to 100% effectiveness. These have been widely used in cattle herds and sheep flocks.

However, in sheep flocks where there has been widespread usage of the product over several years, resistant fluke have emerged, which means that the efficacy of the product is diminished in some sheep flocks.

Rumen fluke

In the last few years, results on faecal egg counts started to differentiate between liver fluke eggs and rumen fluke eggs. Rumen fluke have been around for a long time, but only became a hot topic once labs differentiated between fluke eggs and showed their prevalence. Liver fluke can decrease cattle thrive and can be fatal. Rumen fluke, although they will affect thrive, will not kill an animal.

There are only two products on the market that will kill rumen fluke. These are Zanil and Levafas Diamond. Both contain the active ingredient oxyclozanide.

Vets are telling farmers to be very careful with the use of both products, as they are the only way to control rumen fluke.

It is advised that where farmers think there is a specific problem with rumen fluke in an animal, they should treat just that animal. Blanket treatment is not advised due to the risk of resistance emerging.

Farmers should also be aware that oxyclozanide is only effective against rumen fluke and mature liver fluke. If there is a rumen and liver fluke problem, a dosing strategy should be devised to tackle each separately and consult your vet before doing so.

Cattle weight

In order for any dose to be effective, it is essential that it is given accurately. Because doses often have dosage details by cattle weight, it is essential that the animal’s weight is estimated correctly.

Underestimating weight will mean that the animal is not getting enough of the active ingredient and the efficacy may be impacted.

Overestimating weight will mean that cattle are receiving too much of the active ingredient. Both can affect resistance of parasites to doses in the long term.

Withdrawal dates

It is crucial that farmers pay heed to withdrawal dates before implementing their dosing plan, particularly for finishing cattle.