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Types of mastitis

Sub-clinical mastitis

This leads to reduced milk yield and so slower lamb growth rates. This is more common with each year a ewe lambs and ewes of 6 or more years old are typically sub-clinically infected, and their lambs grow more slowly. All ewes have bacteria in their udder, but are not necessarily diseased. Research in our group is exploring the bacterial communities in healthy and diseased udders to try to understand any differences between them.

Acute mastitis

A ewe might be off her food or hanging back from the flock; she might appear lame on a back leg because of a painful udder. The affected udder can be hot, swollen and very painful or cold and discoloured. Lambs may look hungry as the ewe refuses to suckle them. Milk might be watery or pus-like possibly with blood. Farmers report between 0% and 5% of ewes with acute mastitis per year, the average is about 1% and averages above this are a concern.

Chronic mastitis

Palpable lumps or masses in the udder. These are abscesses formed by bacteria; they can be any size or shape and feel different to normal udder tissue. Ultimately they can rupture and reform, so may not be present every time the udder is palpated. Farmers report culling 2 – 8% of the flock with udder masses at weaning.

Good udder

Good udder

lump.jpgLumpy udder