Efforts to combat the rising tide of pigeon fever among horses in the United States have suffered a blow, with sales of a conditionally licensed vaccine voluntarily suspended.
Boehringer Ingelheim Vetmedica Inc said it had placed a voluntary stop sale earlier this month on its Corynbebacterium Pseudotuberculosis Bacterin-Toxoid vaccine, more commonly known as the equine pigeon fever vaccine.
The company said it made the move following reports of unexpected post-vaccination gastrointestinal tract events observed in some horses.
During the required pre-licensing safety studies, these events were not observed, it said.
The company said it believed a voluntary stop sale was in the best interests of customers and their horses.
“A comprehensive investigation is under way to understand the unexpected post-vaccination events observed in some horses, as these events were not observed during the pre-licensing safety studies,” a spokesman said.
The company announced on March 5 this year that it had been granted a conditional license for the vaccine by the US Department of Agriculture.
A conditional license is granted when there is a demonstrated need in the field for such a product. A conditionally licensed vaccine must have demonstrated field safety and a reasonable expectation of efficacy.
The vaccine was available only in the US.
Pigeon fever is an alarming and unpredictable disease. There has been a surge in the number of cases in the US over the last 5-7 years.
C. pseudotuberculosis is a soil-borne bacterium that can persist for months in a variety of environmental conditions, and is primarily spread to horses through open wounds or flies.
Prevalent in hot, dry climates, the disease was once thought to emerge sporadically in a few Western regions, but has recently appeared in areas such as Florida and Kentucky.
Pigeon fever is so named because of the basketball-sized pectoral abscesses that can develop. They can occur in other sites as well, including internally. Severe limb swelling can also result from infection.
Although less common, internal abscesses arising in the liver, kidney, spleen and lungs have proven to be difficult to diagnose and treat, and have a mortality rate as high as 40 percent, even with treatment.
While easier to diagnose, treatment of external abscesses may be both very time-consuming and expensive as they must be lanced, drained and undergo daily cleaning until the infection in the area subsides.
Medical and technical questions should be directed to the BIVI Veterinary Technical Services Team at 1-866-638-2226 (Mon-Fri 8am-5pm CST).
Study confirms rise in pigeon fever in the US.