One of the best pieces of advice I was given was before drenching (and especially after moving to a new property) to have the cattle (herd) analysed for any or type of worms.
The LHPA provide a kit for taking the samples and you send them off and within a couple of days you get emailed the test results. Costs for the lab are paid by you but they help with the results and advice. We did a basic worm and most expensive liver fluke.
I've been really concerned that our herd would have liver fluke after such a wet season, on land with gullies and wet spots that they've had feed and water out of, and three of the cows are still in really poor condition.
Well yesterday I got the results and intend ringing the LHPA vet to discuss this morning.
Our results were 0 for worm and liver fluke but they have 'stomach fluke', I hadn't heard of stomach fluke but on reading about it, usually it doesn't cause a problem as they build an immunity to them, but if they get overloaded it's a problem.
I have to say the money spent is well worth knowing exactly what we're dealing with and it will be interesting what the vet can tell me.