Know your enemy Lambs

Mar 20, 2014
Posted by: brian
Category: Sheep Tag News

6 of the biggest and badest parasites to watch out for this lambing season!

Take action and protect your lamb crop.

Internal parasites can deliver devastating effects on your lamb crop. They affect growth rate and cause huge amounts of damage to the internal workings of your lamb.  Pre-emption, identification and the elimination of parasites as early as possible is key to success! Here are six of the worst to look out for.




Syptoms - stunted growth, potbellies, diarrhoea, sometimes no visible symptoms.


Roundworm tends to thrive in the intestinal guts of the animal. They gain their nutrients by effectively robbing the host animal of theirs, feeding on their stomach content. The females release their eggs into the faecal matter of the animal, meaning it posses a risk when it contaminates grass and is ingested by another animal.  It can majorly impact the growth of lambs at grass.

Discussing with your vet or adviser and establishing a worm control programme is a must.


Nematodirus (thin necked intestinal worms)


Symptoms – diarrhoea, loss of condition, death.

Nematodius does not infect fully-grown adult sheep, meaning it is purely a lamb-to-lamb infection. Risks of it are usually higher in pastures that have house lambs the previous spring. The eggs of this virus are highly resistant to both heat exposure and drying out, AND extreme cold temperatures. This means that problems tend to surface when the weather warms AFTER a sever cold snaps or heat spells.


It takes a year to complete its life cycle, meaning that risk in pastures is largely determined by grazing history. For those whom managing pastures long term is not a viable option, medical treatment is also available. Consulting with your vet about treatment will ensure you get a product that works best for your system.




Symptoms – diarrhoea, failure to thrive, loss of condition


Coccidiosis is caused by a microscopic parasite called Eimeria. The effects of Coccidiosis can be observed in stressful situations where the immune system of the animal may have taken a knock, or where there are high parasite numbers, for example in overcrowded housing with poor hygiene, or where older lambs excreting parasite eggs are mixed with younger uninfected lambs. Stressful events include poor weather, castration, mismothering and poor intake of colostrum, transport or turn out.


Coccidiosis strikes lambs at four to six weeks, and carries a high mortality rate. Those who are not killed by the disease often do not recover to full health. 

It is not always possible to prevent coccidiosis, but monitoring housing capacity and maintain a good standard of hygiene are solid preventative steps.


Liver Fluke


Symptoms – failure to thrive, loss of condition, death.


Liver fluke is a parasitic flat worm that relies on warm and moist conditions for survival.  As the adult fluke parasite feeds on blood, its presence leads to anaemia in infected sheep – this means that gums and membranes will be comparatively paler to healthy sheep. Consulting with your vet and planning a control strategy is an essential order of business in order to protect your flock. Although the disease can be treated, preventing the matter further could save you time and money in the long run.




Symptoms – agitation in the animal, odour, shed wool, infestation of other flies.

Blowfly is the main external parasite affecting sheep in the summer months. If left untreated, fly strike can be fatal. Prevention is the best form of control with blowflies, and a number of pour-on insect growth regulators are available.


Ticks and lice


Symptoms – visible parasites, failure the thrive, death.

Little spidery type creature that latch to the sheep and suck its blood, live in the animal’s wool, and generally get in amongst scabs and sores. Nasty things that should be destroyed at all costs.


Pre-emptive measure are good steps to ensuring the well being of your lamb flock, but always make sure you consult closely with your vet as they will be able to deliver you the most suitable information on what treatments will be the most effective for your farm system.






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