Warkworth Veterinary Services Ltd
We are a seven vet mixed practice, serving the greater Warkworth and Wellsford regions, from Puhoi in the south to Maungaturoto in the north and from east to west coast in between.
Species-specific metabolism of drugs
Cross-grazing of different species (such as sheep and goats)
Buying in stock with unknown parasite burdens
Stock access to long-standing water sources
Dench resistant parasites
Repeat grazing of young stock on the same pastures year after year.
Assess the parasite burden (drench only when needed)
Drench wisely (appropriate product and dose)
Perform a drench check (ensure the drench is working)
A Faecal Egg Count (FEC) is a cheap, quick and effective method that will answer steps ONE and THREE of this drenching approach. All you need to do is collect a fresh faecal sample from your stock (4-6 samples in large mobs is enough) and drop it into the clinic. We can usually have a result the same day and then advise if drenching is appropriate for your stock class.
In New Zealand, most parasites of significance in livestock have similar lifecycles and will flourish under warm, wet weather.
Early spring has traditionally been the parasite's friend, any parasite eggs on pasture that have survived the winter will start to develop and be infective to grazing stock. Once ingested, they take around three weeks to develop and produce eggs that fully re-infect the pasture.
The traditional approach to drenching has been to drench a couple of times in spring at one-month intervals, then once in autumn to limit parasite numbers that overwinter. However, with the emergence of drench resistance and a changing climate, it is no longer that simple, and you may need to drench any time of year.
The parasite season starts as warm and wet weather breaks the winter cycle, occurring in august. Therefore, collecting faecal samples for testing before drenching is essential to measure efficacy post drenching.
Depending on your stock type and density, you may need to drench every month through spring and into summer if it remains wet due to high parasite loads on pasture. This is not ideal due to cost and the risk of parasite resistance, so performing another FEC before each drench or at least after the 3rd or 4th drench in spring is recommended, so you know that continuing monthly drench cycles is warranted.
Perform an FEC whenever parasitism is suspected, or weather conditions favour development. In the Rodney region, this may be any time from late winter through to early winter the following year if wet, warm weather persists for 2-3 weeks or more.
• What drug active is appropriate (have I proven efficacy in the past?)
• What route of administration should I use?
• What dose should I use?
There are only five drug actives on the market, they are packaged as either single or multi-drug formulations, and in general, you should use an old generation active before a new generation and the least number of actives required for efficacy.
As a broad guideline, this means using the "fewest actives that work" (confirmed by doing a drench check as outlined in step 3). Although, the reason for this approach is due to drenching resistance, using a multi-combination or new generation drench comes with the risk of developing resistance to those actives. Once this occurs there a few options available.
Injectable, oral and pour-on formulations are available. Double-check your equipment and administration method labelled on the packaging. Also check the expiry date on the product (Do not use the expired product). With pour-on drenches avoid wet weather.
Drench resistance primarily develops due to under dosing, so getting this right is very important. When drenching, always drench the entire mob of any stock class to the weight of the heaviest animal in that mob. If in doubt about weights, estimate higher rather than lower.
Use the "fewest actives that work"
Does all animals to the weight of the heaviest in the mob
Strictly follow the labeled with-hold periods for milk and meat going for consumption
Ensuring your drench has actually worked is very important, particularly for the first drench of the spring season and the last drench in autumn. Without this you may be wasting money on a drench that is not effective or an expensive drench that could be replaced by a much cheaper one.
Perform FEC 7-10 days post drenching to confirm efficacy. Record results, use this to aid drench choice at the next dose.
We are a seven vet mixed practice, serving the greater Warkworth and Wellsford regions, from Puhoi in the south to Maungaturoto in the north and from east to west coast in between.
