AAEP Hot Topic: Potential Preventive for Foal Pneumonia

Researchers at Texas A&M University find evidence that a rare metal may help protect newborn foals from pneumonia. From the editors of EQUUS magazine.


The 2006 American Association of Equine Practitioners (AAEP) convention wrapped up December 7 in San Antonio, Texas, where more than 100 presentations highlighted the latest research on topics such as lameness, colic reproduction and hoof care. EQUUS magazine was on hand to cover the event.

One presentation that generated great interest among attending veterinarians described an investigation of the potential benefits of a rare metal called gallium in preventing foal pneumonia. The study was conducted by Ronald Martens, DVM, from Texas A&M University.

The rare metal gallium may help protect newborn foals from Rhodococcus equi, the bacterium responsible for a severe and potentially fatal pneumonia similar to tuberculosis in people.

Although clinical signs of R. equi are not usually evident until foals are 1 to 2 months old, current evidence strongly suggests that youngsters generally become infected shortly after birth. However, say researchers at Texas A&M University, laboratory tests indicate that gallium may help interrupt the progression from R. equi infection to full-blown disease.

When exposed to gallium in a test tube, R. equi bacteria fail to thrive and eventually die, says Ronald Martens, DVM. In addition, mice given oral doses of gallium maltolate before being infected with R. equi had significantly lower bodywide concentrations of the bacteria six days after infection than did mice who were given a nongallium control treatment.

"R. equi, like certain other types of bacteria, pick up iron from the blood for use in several crucial enzyme systems," explains Martens. "Gallium is similar enough to iron that the bacterial organisms [mistake it for iron] and pick it up. Since they cannot utilize it, however, they cannot multiply and eventually die off."

Gallium was selected for investigation because in mammals it concentrates in areas of infection, inflammation and cancer. In addition, the metal causes the death of Mycobacterium tuberculosis, which is responsible for tuberculosis in people.

Martens says that the studies in mice are encouraging enough to warrant further investigation in foals: "We are working on the hypothesis that the oral administration of gallium maltolate for short periods immediately after birth will provide protection until the foal's own immune system is capable of controlling the bacteria."

Toxicologic and pharmacokinetic studies have shown that gallium maltolate can be safely given to newborn foals in the desired dosages, says Martens. "The next step is to study it in the field using a group of at-risk foals."