Pneumonia is commonly seen in weaned lambs in the summer and early autumn months – hence the condition is often referred to as summer pneumonia. In some cases, the only signs may be occasional coughing or “ill-thrifty” lambs. Hot weather is commonly associated with outbreaks of pneumonia. Stress due to transport and mixing of mobs from different sources are also contributing factors. The use of pour-on fly repellants should be considered during an outbreak.