Drenching calves and lambs - FAQs

Drenching calves and lambs - FAQs

How do we know our animals have parasites?

Common symptoms of internal parasites include diarrhoea, dags, ill thrift, slow growth, coughing, pale mucous membranes (in sheep) and even death.
To monitor worm burden, we use faecal egg counting: counts of over 500 eggs per gram (epg) of faeces to indicate a drench would be useful. Counts over 1000 epg indicate the animal is being affected by worms.

When do we start drenching?
Young animals pick up parasites as soon as they start grazing, so the best time to begin drenching is at weaning at three months old. After this they should be drenched every 28 days over the danger period of summer and autumn.

What do we drench with?
The type, amount and rate of drenching depends on the worms, animals and property. Call into your local Anexa FVC clinics for a chat with one of our Vets, sales reps or counter staff and get a tailored plan.

Do our older animals need drenching?
Older animals are often not as affected by internal parasites and don’t shed as many eggs onto your paddocks. However, if there is a high burden in the paddocks or if the animals’ immune systems are affected by other diseases, parasites can take advantage and your animals may benefit from a drench.

Other helpful practices include:
• Not grazing paddocks too low so as to minimise the pick-up of parasites
• Keeping a low stocking rate so as to minimise the parasite load on paddock
• Cross grazing with another species e.g. cattle and sheep
• Resting paddocks and cutting hay or silage
• Keeping animals well fed and healthy to minimise the effect parasites have on them

Daggy sheep?

Causes of dags include long wool, scouring and tails. It is this time of year that shearing should be done to prevent dags and overheating.

The consequence of dags is FLYSTRIKE! This is when flies lay their eggs in warm wet wool. Maggots hatch out and cause damage to the skin which can be life threatening to sheep. The most common areas affected are around the bottom, over the back and on the bell, and in rams around the genitals.
Symptoms include itching, nibbling, dark areas of wool, stamping feet, swishing tails and depression (lethargy and drooping ears). Sheep isolating themselves from the flock are usually not feeling good.

Treatment - shear the wool to 5 mm and apply an organophosphate insect killer. Examples include strike powder, maggo or zenith spray on. Fly spray is NOT recommended. Pink wool-less areas should be covered with a zinc based sun cream to prevent sunburn. Depending on the severity you may need to call your Vet for further treatment.

Prevention - insect growth regulators (IGRs) can be applied five weeks post shear or earlier as required. This prevents flystrike by killing larvae as they moult and they tend to last 12 weeks. Because they act on the larval stages they will not kill actively eating maggots so this treatment is separate.

The exception is Cyrex which stops active feeding of maggots within minutes of contact, kills maggots or moves them out of wounds and off the sheep within hours and then also continues to provide protection from flystrike for up to 12 weeks.

Cyrex is available in 250ml bottles which must be diluted on the ratio of 10ml Cryex to 5L go water

Give your local Anexa FVC clinic a call if you have any concerns.



Date Added: Wednesday, 23rd November 2016


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