Rhodococcus equi in Foals

January 12, 2009 (published)

In spring, we have to start thinking about diseases that can affect foals. Today on the program I am going to talk about pneumonia in foals caused by Rhodococcus equi. Rhodococcus is a bacterial organism that lives inside cells in secretions of the respiratory tract of foals and causes a severe pneumonia with abscesses in a foal's lungs. Most affected foals are between 1 and 6 months of age. The unusual fact about Rhodococcus is that it is commonly found in the feces of grazing animals and at most horse farms. Some of the Rhodococcus organisms are capable of causing disease and some are not, and both are usually found at most farms.

Most foals become infected with Rhodococcus by inhaling the organisms; the more organisms that are in the air, the greater chance of infection. To decrease the number of inhaled organisms, one thing you can do is to avoid keeping foals in dry dusty areas. It is much better to keep foals in larger areas covered with grass than small paddocks. Also, it has been shown that watering down small paddocks before bringing in foals can decrease the number of airborne organisms. It is recommended to avoid keeping large groups of foals together as it has been shown that Rhodococcus can be contagious between foals, so the larger number of foals that are together increases the dust and chance of exposure. Infected foals should be isolated because infected foals have high numbers of disease, causing Rhodococcus in their respiratory tract. Any foals found breathing hard and lethargic should be examined by your vet immediately.

VIN News Service commentaries are opinion pieces presenting insights, personal experiences and/or perspectives on topical issues by members of the veterinary community. To submit a commentary for consideration, email

Information and opinions expressed in letters to the editor are those of the author and are independent of the VIN News Service. Letters may be edited for style. We do not verify their content for accuracy.