Texas A&M researchers have discovered they can reduce the incidence of foal pneumonia caused by Rhodococcus equi by giving the antimicrobial drug azithromycin during foals’ first two weeks of life.

Rhodococcus equi (R. equi) is a pathogenic (disease-causing) bacterium that causes pneumonia in foals. It is a common soil-dwelling bug that results in important economic losses within the breeding sector of the equine industry.

“Identifying ways to prevent R. equi pneumonia is important because diagnosis can be challenging, particularly early in the course of the disease, and treatment of R. equi is expensive, time-consuming, and can be associated with serious side effects,” said Keith Chaffin, DVM, MS, Dipl. ACVIM, professor of equine internal medicine at Texas A&M.

There is growing evidence that foals are infected with R. equi within a few days after birth. The infection subsequently grows until overt signs of R. equi infection (fever, cough, nasal discharge, lethargy, progressive respiratory distress) are noted, typically around 30 to 90 days of age