There has been a gradual increase in the incidence of external parasites, namely sheep scab and lice in recent years. Many farmers and vets point in particular to a higher incidence of lice last winter, as was also the case in housed cattle. Both sheep scab and lice are highly contagious and once they gain entry into a flock, can establish and spread very quickly. Speaking at last week’s Nutrias and Bimeda sheep seminar in Roscommon, Bimeda’s Morgan Lane said that dipping at this time of year is the most appropriate option to treat all external parasites in a single treatment.
There has been a gradual increase in the incidence of external parasites, namely sheep scab and lice in recent years. Many farmers and vets point in particular to a higher incidence of lice last winter, as was also the case in housed cattle. Both sheep scab and lice are highly contagious and once they gain entry into a flock, can establish and spread very quickly.
Speaking at last week’s Nutrias and Bimeda sheep seminar in Roscommon, Bimeda’s Morgan Lane said that dipping at this time of year is the most appropriate option to treat all external parasites in a single treatment.
“There are options for farmers who do not have access to dip sheep, but these are generally more complicated and require a combination of injectable and pour-on products.
“We as a company have injectable products for sheep scab and Ectofly pour-on for lice and ticks. These are generally recommended for targeted treatment and our advice for complete control, if possible, is dipping at least once a year.”
Dipping tips
Discussing dipping, Morgan says that dipping requires investment in time and purchasing products and, as such, it is important to follow best practice guidelines to ensure optimum control and a good return for this investment.
“There is no doubt that dipping works excellently and also gives sheep an overall boost. However, we regularly see farmers not getting the most out of dipping through flawed practices. The following guidelines are all critical in ensuring effective control:
Do not add colours: Adding colouring agents to prepare sheep for shows or sales may seem worthwhile by completing two tasks at once, but it can be detrimental. It can cause chemicals to separate, making dipping useless in combating external parasites or worse still, it also leads to a risk of poisoning sheep. Reduce the pressure on sheep: Sheep should be dipped early in the morning or on a cool, dry day. Allow sheep to rest pre-dipping if they have been active for a period while flocking. Ideally, dip sheep when empty – it puts less stress on the animal and also the operator in handling the sheep. Post-dipping lameness: Post-dipping lameness occurs when sheep are dipped in solution from previous days’ dipping or in heavily contaminated mixture. Where it hits, it can be a big problem, with sheep going lame two to four days after dipping. Problems can last for a few weeks and, in worst cases, requires continuous and costly veterinary intervention. Sheep should only be dipped in solution prepared before dipping takes place and sheep should never be dipped in solution prepared the previous day. Follow manufacturers’ guidelines: This is self-explanatory – different products vary in their control, usage guidelines and also chemical composition (organophosphate (OP) and non-organophosphate dips). For example, Cyperguard and Ectoflits are very similar, but Cyperguard probably shades it in terms of giving better control of ticks and, as such, this is the dip we recommend most for hill areas. Some farmers also have preferences on using OP or non-OP dips. Correct concentration: I have left this point until last as, for me, it is one of the most important that I want to spend a bit of time on. Every time a sheep passes through a dipping tub, she removes solution and generally walks away with two litres of solution, part of which is returned through flow back from the draining pen. However, it is important to note that the active ingredient strips to wool (holds to wool) and therefore while there is solution returning to the dip tub, it is mostly water. If the active ingredient concentration drops below a certain level, sheep won’t receive adequate treatment. It is for this reason that it is critical to monitor the number of sheep passing through and top up the tub with the recommended volume when required. Over time, the solution will become weaker, even if topping up is taking place, and, at a certain stage, it is highly recommended to mix a fresh batch of dip. This will also depend on contamination brought by sheep into the tub, but a general rule of thumb is that one sheep can be dipped for every two litres that the dipping tub holds before replacing. For example, if the dipping tub holds 1,000 litres, it is recommended to replace and mix a fresh solution after 500 sheep have passed through.Identify parasite
Outside of dipping, there is no product that covers both sheep scab and lice. As such, it is hugely important to make the correct diagnosis.
For sheep scab, there are numerous products on the market, with active ingredients such as ivermectin, moxidectin or doramectin.
Take note that most products require retreatment seven to 14 days later, with the exception of products such as Dectomax or Cydectin 2% LA, which is available in Northern Ireland. The same can be said of lice and it is important to read manufacturers’ guidelines closely or seek veterinary advice.
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Focus: Winter animal health
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