It’s that time of year when we get phone calls about coughing lambs and ways, we can help to treat animals at the time.
Unfortunately, pneumonia in lambs is very difficult to treat once symptoms have occurred, so the best treatment is prevention!
Pneumonia in young sheep can be caused by a number of different bacteria, viruses and animal factors. In order for the defences of the lungs to be overwhelmed and pneumonia to become obvious, all three of these causes are often present. Pathogens (the bugs that cause disease) find it much easier to cause disease when animals are undergoing periods of stress. This often involves activities such as mustering and yarding, often in hot dusty conditions. In particular issues arise when lambs begin to open mouth breathe which allows easy passage of bacteria and viruses into the upper and lower airways. Other stressors may include shearing (especially if followed by unexpected bad weather), dipping, facial eczema, travel or the influence of lungworm.
Once the defences of the lungs have been overcome and the bacteria/viruses have set up shop the body can respond in several ways. The first is the body can have a chronic, non-progressive pneumonia that is often present in a single lung lobe. The lung becomes grey in colour and can sometimes have abscesses within it. The second is an acute fibrinous pneumonia where many or all lung lobes become dark in colour, with sheets of yellow fibrin sticking between the lungs and the body wall- also known as pleurisy. Both of these body responses can show similar signs- coughing, lagging behind mob and heavy breathing. If severe enough death can result, however it is more common to have “sub clinical” animals who show do not show signs.
Either of the forms of pneumonia are an economic concern for farms; as well as direct losses there is also a reduction in weight gain and lower wool production. A lamb with 20% of its lung surface affected by either form of pneumonia can cause a 50% reduction in weight gain and therefore more days to slaughter.
Unfortunately treatment of individual animals is unrewarding once clinical signs have set in. Occasionally long acting antibiotics may be indicated, but only after discussion with your vet. Prevention is the best option to manage this disease mainly through reducing stressors; minimising yarding, mustering in cooler mornings and trying to prevent open mouth breathing. Sprinkler systems may also help to dampen dust in the yards and prevent inhalation. As well as these direct measures of prevention good feed, access to fresh water and good parasite management will ensure lambs have the best possible immunity and reduce chance of infection.
