Step Away from the Drench Gun
Weaner anaemia is a bacterial blood parasite. See the dark purple spot on the pale purple red blood cell indicated by the arrow in the picture above? That’s the parasite attached to the blood cell in the yellow lamb above’s blood. Our talented vet student Amy did a blood smear and found the parasites.
M.ovis was previously called E.ovis and is a pretty common disease in north west NSW. A review of the old Narrabri and Walgett RLPB records published in 2012 found that it’s pretty common. 50-60% of cases had marking, mulesing or shearing in the 8 weeks prior to clinical cases.
There are carrier animals in flocks. A 1991 study found that 90% of Victorian flocks and 68% of Queensland flocks had carriers. When young lambs are stressed and there is a management procedure that involves blood transfer between animals, the disease spreads from carrierr sheep to naive sheep. The parasite multiples, attaches to the blood cells and the body recognises them as damaged and so destroys them. Soon, they run low on red blood cells and look anaemic.
The red blood cell fragments get processed by the liver and spleen, clogging up the bile ducts, so the animal looks jaundiced.
There is no treatment, if left alone they recover in 4-6 weeks time. Don’t yard them! If in doubt, drop in a worm egg count sample or get us out to look at some sheep. The mortalities if left alone are 0-5% but can be much higher if they are yarded, chased or handled. So put down the drench gun!
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