Pneumonia is major killer of foals


Pneumonia is the most common disease in foalsOne of the most common diseases in foals six months and younger is pneumonia. Although many different organisms can cause foal pneumonia, Rhodococcus equiis is considered the most common culprit in a severe case. According to a statement released by the American Association of Equine Practitioners on behalf of the Equine Research Coordination Group, a nationwide survey indicated that respiratory disease is the third-leading cause of disease in foals and ranks second as a cause of death, following injury or wounds.
Because foals’active immune systems are still developing, they are susceptible to a number of infectious diseases. A Texas  A&M study found that in foals, respiratory disease was the leading cause of disease and death. During a 2004-2005 study at a Kentucky breeding farm, 30 percent of foals developed R.equi pneumonia.
No horse breed or geographical region in the U.S. is exempt from foal pneumonia, which can be caused by a bacterium that is often present in horse farm soil and grows in the manure of grazing animals. The R.equi bacterium is similar to the one that causes tuberculosis. Like TB, foal pneumonia caused by R. equi develops slowly and by the time clinical symptoms are detectable, the disease is in a relatively advanced stage. Indeed, some foals don’t show signs of respiratory distress until the disease is irreversibly severe. Although effective treatments exist, waiting until signs develop can result in a therapeutic course that is prolonged with lower chances for success. Thus, there is a critical need to discover methods for preventing foal pneumonia.
Investigators at several institutions have been working, often collaboratively, to further our understanding of the bacterium and the disease. Those studying the disease are committed to improving foal health. Collaboration greatly increases the resources and opportunities for continued major breakthroughs that could reduce the burden of the disease.

Much work still remains to build on these findings, including understanding the environmental conditions that might make infection more likely among foals. Additionally, the findings are likely to have application to other infectious foal diseases, such as diarrhea and sepsis, a major killer of newborn foals. Studies funded by the Grayson-Jockey Club Research Foundation ( and the Morris Animal Foundation ( are currently in progress. Successful conclusion of these projects will help guide the research community toward the next steps in combating the disease.
The equine veterinary community is issuing a collective call for support in this endeavor. Donations to the organizations named above as well as the American Quarter Horse Foundation (, the American Association of Equine Practitioners Foundation ( or your favorite veterinary school will help support foal pneumonia research and hopefully enable the discovery of a vaccine that will prevent the disease or ameliorate these early infections and provide an effective disease control.
Contact the American Association of Equine Practitioners Foundation ( for information on how to make donations for equine research, or call (800) 443-0177 (within the U.S.) or (859) 233-0147. The AAEP is coordinating on behalf of the industry through the Equine Research Coordination Group (ERCG), which is comprised of researchers and organizations that support equine research.


  1. The article was very informative. Last night we had to have our 3 month and 1 week old TB foal euthanized. He had been hospitalized for the past week, after fighting a pneumonia for the past 6 weeks. He was foaled at Vessels Stallion Farm, Bonsall, CA and given two plasma IV’s to build up his immune system. The IV’s are routinely given to all foals at Vessels. We brought him home to Arizona when he 7 weeks of age, once his mother was pronounced in foal for her second pregnancy. He commenced antibiotic treatment on Kentucky Derby day, May 5, 2007. He died last night five weeks later on Belmont Stakes day.
    The vets at AZ Equine Diagnostic are still working on his case to see exactly what infection he was harboring.
    It is so sad and heart-breaking. Other past TB foals we’ve bred were never sick, but they were foaled at home and not in a situation of several hundred other horses. I would like to find out exactly what was wrong with our foal, and why it could not be effectively treated. Our vets are still awaiting results of culture samples, and will perform an autopsy. He did not have rhoddococcus.
    Thank you for the article.


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