A recent survey suggests commercial sheep farmers see 0 – 5 per cent cases of clinical mastitis in their ewes each year, with a few farmers reporting more than 20 per cent of ewes affected. Louise Hartley asks experts to give their advice.
When ewes with chronic mastitis (masses or lumps in the udder) are added to those with clinical mastitis, about 10 per cent of the national flock is culled or dies from mastitis each year. In addition to early culls and deaths, a further cost of mastitis comes from lower milk yields and slow-growing lambs.
The University of Warwick has been carrying out a study of teat lesions and mastitis in ewes. Prof Laura Green says: "Clinical mastitis is typically caused by bacterial infections and farmers might identify affected ewes because they go off their feed, hang back in the field or are lame. The udder might then be hot or cold and change colour and the milk might be discoloured.
“Sometimes ewes are picked up with lumps in their udder; these are abscesses which are also a sign of mastitis.
“As part of our research we studied teat lesions caused by bites from lambs and found they were most common in first time lambing shearlings. From other studies we know first time lambing ewe lambs or shearlings feed their lambs more slowly than ewes that have previously had lambs.
This is probably because the udder tissue which makes milk forms as lambs feed, so as the lambs grow and need more milk the ewe grows more cells in the udder that make milk. To get sufficient feed lambs suck for long periods of time and this might increase the trauma to the teat.
In addition, in all ages of sheep teat lesions were most common when lambs were about four weeks old; this is the peak demand for milk from lambs because soon after this they start to eat more solid foods.”
First time lambing ewes
For many farmers these ewes are most at risk of mastitis. The ewes are still growing and the udder is still developing during lactation. As a consequence they produce less milk and let it down more slowly than ewes which have lambed before, so the risk of teat lesions and butting of the udder is high.
Management and treatment
Regular careful observation of the flock is the most sensitive way to detect new mastitis cases, the ewe will initially be unwilling to allow her lambs to feed because of the pain associated with suckling. This means lambs pester the ewe, appear hungry and unsettled. As the disease progresses the ewe becomes toxaemic and ill and start to separate from the main flock, she will appear dull and listless and often lame on a hind leg due to the severe pain associated with the infection. Ewes must be treated quickly before toxaemic shock takes hold if they are to have any chance of survival.
Udder with acute mastitis
Peers Davies, vet at ProOvine sheep veterinary services, says: “In very many cases ewes are only identified when the udder is already discoloured and she is obviously ill and unwilling to eat or drink. In these cases euthanasia should be seriously considered instead of treatment as the chances of recovery are low and further suffering should be avoided.
“If caught early some cases will recover from the acute phase of the disease and either develop chronic mastitis [lumpy udder] or in more serious cases they will slough the infected portion of the udder over a few weeks, which makes good blowfly control an important concern.
"All recovered ewes need to be culled and records kept of the of cases seen including: age of ewe, date, group, location, BCS, number of lambs and any concurrent disease such as orf in order to identify patterns and potential risk factors as part of your flock planning.”