If a newborn foal seems weak and shows signs of general illness and difficulty breathing, he might have a chlamydial respiratory infection. | Photo: Anne M. Eberhardt/The Horse

If a newborn foal seems weak and shows signs of general illness and difficulty breathing, he might have a chlamydial respiratory infection. According to Australian scientists, Chlamydia psittaci, which causes pigeon fever in humans (not to be confused with equine pigeon fever), can infect the lungs of young foals and even kill them.

“It is very difficult to say whether previous cases have been overlooked or whether this is an emerging disease and these are the ‘first cases,’ so to speak, but it is likely that some cases have been, and likely continue to be, overlooked—particularly in regions where routine testing of sick foals is not currently undertaken,” said Sarah Louise Gough, DVM, previously a medicine resident at the Veterinary Clinical Centre of the School of Animal and Veterinary Sciences at Charles Sturt University, in Wagga Wagga, New South Wales, Australia.

In an international first, Gough and her fellow researchers confirmed 15 cases of sick newborn foals infected with C. psittaci, leading to 13 fatalities. Scientists have previously detected the bacteria in a few adult horses, associated with respiratory disease and abortion, and occasionally in healthy horses. However, they had never reported C. psittaci as a cause of respiratory disease in foals prior, she said