Joe Carter, DVM
30 Racing Quarter Horses Test POSITIVE for Coggins
than 30 racing quarter horses in California were recently diagnosed
with the virus, so it is critical that horse owners follow regulations,
said LSU AgCenter equine specialist Neely Walker.
Equine infectious anemia (EIA) is an infectious viral disease that
affects horses, mules, donkeys and zebras. It is also known as swamp
fever because of its prevalence in the Gulf Coast region.
There is currently no effective treatment or vaccine for EIA. The
survival rate of horses infected with EIA is high, Walker said, but
those animals can threaten the health of their offspring and other
The virus is typically transmitted from one horse to another by
blood-sucking insects, such as horseflies, deerflies, mosquitos and
gnats. Many epidemics of EIA have also been linked to the reuse of
hypodermic needles or nonsterile surgical equipment, Walker said.
EIA can present itself in three different degrees of infectiousness: acute, chronic and inapparent.
horses are inapparent carriers of EIA and appear normal, displaying no
clinical abnormalities associated with infection,” Walker said.
“However, they are lifelong carriers of the virus.”
acute form of EIA is the most damaging and is difficult to diagnose.
This form often occurs seven to 30 days after the first exposure to the
virus and may cause fever and hemorrhaging on the mucus membranes,
If the horse survives the acute stage of EIA, it may develop chronic
symptoms such as fever, small patches of hemorrhages on the mucus
membranes, depression, weight loss, anemia and swelling of the legs and
Diagnosis of the virus was not possible until the 1970s, when Leroy
Coggins developed a test, which became known as the Coggins test.
Today’s tests can produce results in less than one hour.
testing allows timely identification of infected animals and removal of
those animals from herds, potentially preventing the spread of the
disease,” Walker said.
In Louisiana, all horses are required to have a Coggins test performed
annually. Foals must be tested no later than one year after being born.
Animals that test positive for EIA in Louisiana must be euthanized or
sold for slaughter only. All animals located within 200 yards of an
animal with EIA are subject to quarantine and require a negative test
before a quarantine release will be issued.