The extreme shifts in temperatures in Australia can see summer temperatures hit 40 degrees celsius or more, then drop dramatically and rapidly as cold fronts roll in.
These temperature extremes are challenging, and one common finding during summer, particularly in young stock, is pneumonia.
And recent work carried out by Meat and Livestock Australia (MLA) shows the cost of pneumonia in Dorset flocks is relatively higher than the overall national flock average.
Yet in Australia there is no registered vaccine for summer pneumonia in sheep.
Dr Stuart Barber, a lecturer in veterinary science from the University of Melbourne, speaking at the National Poll Dorset Conference in Orange last week, said the key environmental influences that exacerbate the problem are dust, flies, animal stress, unbalanced diet and inadequate shelter for livestock.
He said no single organism causes summer pneumonia, however we commonly see mannheimia haemolytica present, which is known to be carried in the throat of lambs.
"When lambs get stressed in the summer, when we have big changes in the weather or we perform stressful practises like shearing, crutching, drenching or dipping, that is when we start to see outbreaks of the disease," Dr Barber said.
"It is also often associated with another bacteria called mycoplasma."
He said when pneumonia hits the animal we are likely to see a rapid decline in their health.
Signs to look out for are a rapid weight loss, reduction in appetite and coughing.
But the subtle early signs can make the disease difficult to identify.
"It's even harder to pick up in sheep in full wool because it is more difficult to see weight loss," Mr Barber said.
"Early symptoms can rapidly progress to severe pneumonia with the animal struggling to breathe, which can lead to death."
In terms of prevention, an appropriate antibiotic injected intramuscularly or intravenously is recommended as soon as the disease is recognised.
But when thinking about a long-term prevention, Mr Barber said a vaccine would be the ideal start as a determent the disease.
Yet in Australia there is no current registered vaccines for sheep even though a vaccine is available for cattle against both viral and bacterial causes of summer pneumonia.
Mr Barber said further trials are needed to assess the efficiency.
"As producers we should look at reducing stress, increase shade, and decreasing dust in yards," Dr Barber said.
"When they get dust down their throats that reduces their chance to clear the bacteria from their lungs."
He suggests watering livestock yards to reduce dust when animals are being handled and moving stock in early morning or late afternoon, when temperatures are lower, to reduce overall stress and to avoid having them in yards in full sun.
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