Atypical interstitial pneumonia in grazing adult red deer (Cervus elaphus)

A herd of red deer experienced a small outbreak of atypical interstitial pneumonia on two occasions 3 years apart. The first occasion involved the death of two of a group of 70 hinds and the second outbreak involved a single death in a similar sized group. On both occasions a number of the adults exhibited increased respiratory effort, particularly on exercise. Both outbreaks occurred in July, a few days after moving the herd from a close grazed grass paddock to an aftermath paddock, which had regrown to a good sward. The history and pathology is reminiscent of 3-methyl indole toxicity in cattle.