ate on-farm disease control measures. In states
where the EHM is not reportable, the SAHO does
not have any role in disease control, thus all control
efforts are the sole responsibility of the private
practitioner.During the last 5 years, regulatory officials across
the U.S. have investigated numerous EHM cases
and continue to learn how to most effectively assess
risk and manage these incidents while making sci-
ence-based decisions. In 2014, the United States
Animals Health Association (USAHA) hosted a
meeting to discuss the changes in EHM and science-
based response options for state animal health offi-
cials.
2 Subsequently, great efforts have been made
to have regulatory responses be science based.
However, there are still variations among the regu-
latory responses by SAHOs. Ultimately, the pri-
vate practitioner invariably plays a critical role in
onsite regulatory disease control. In summary, the
California EHM regulatory management experience
demonstrates that prompt isolation of EHM cases
and implementation of baseline premises-level bios-
ecurity practices, which are then enhanced upon
disease detection, can ensure business continuity
and shorter quarantine periods.
Contagious Equine Metritis
In January 2013, a private practitioner evaluating a
17-year-old Lusitano mare with a history of infertil-
ity submitted reproductive-tract samples to the Cal-
ifornia Animal Health and Food Safety Laboratory
for bacterial culture. The culture results confirmed
presence of Taylorella equigenitalis, the organism
responsible for the foreign animal disease, CEM.
During the 2012 breeding season, the index mare
was bred by live cover and artificial insemination to
a 20-year-old Brazilian-origin Lusitano stallion im-
ported in 2003. Testing of the Lusitano stallion
confirmed infection with T. equigenitalis
.
The epidemiologic investigation required tracing
of any mares or stallions potentially exposed to the
infected stallion. An exposed stallion is defined as
any stallion collected at the stallion station during
the 7 days before the infected stallion and the 7 days
after the infected stallion. During the 2012 breed-
ing season, the infected Lusitano stallion was col-
lected at a California stallion station. An exposed
mare is defined as any mare bred by live cover or
artificial insemination to the infected stallion. The
initial epidemiologic investigation identified 11 ex-
posed stallions and one exposed mare. The burden-
some testing protocols, at the owner’s expense, included collection intervals of three sets of cultures
from exposed mares and stallions and live cover of
exposed stallions to two certified CEM-negative test
mares. During the testing protocols, the exposed
horses were under quarantine and unable to be used
for breeding. The stallion station that involved this
incident had six exposed stallions onsite; according
to the stallion station owner, the estimated loss in revenue during the CEM investigation and quaran-
tine period was $75,000. One exposed stallion and one exposed mare were
subsequently confirmed to be infected with T. equi-
genitalis and underwent required treatment and ad-
ditional testing protocols. The second infected
stallion was a domestic 25-year-old Lipizzaner stal-
lion that had semen collected in 2012 at the same
facility as the initially identified infected Lusitano
stallion. The second infected mare was a domestic,
13-year-old, Andalusian-cross breed that had been
artificially inseminated with semen from the in-
fected Lusitano stallion in 2012. This mare was
found to be pregnant. All test positive animals un-
derwent the required additional treatment and test-
ing protocols. The National Veterinary Services
Laboratory determined that the strain of the T. equi-
genitalis from all four infected horses were identical
but failed to match to any previously identified
strains of T. equigenitalis
from the U.S., indicating
these cases were not related to any previous U.S.
T. equigenitalis cases.
Frozen semen collected in 2009 from the index
Lusitano stallion was also confirmed to contain
T. equigenitalis . The epidemiologic investigation
could not determine the time of exposure or source of
the infection of this index stallion, given that the
private practitioner, who managed the pre-2009
breeding of this stallion in the U.S., had retired and
burned his medical records. Fortunately, this inci-
dent had limited scope compared with the large mul-
tistate outbreak of contagious equine metritis in
2008 –2010, which resulted in the detection of 22 T.
equigenitalis –infected stallions and five
T. equigeni-
talis –infected mares at a cost to the industry of $11–16 million.
3,4
In summary, an astute private practitioner and
laboratory diagnostician detected a foreign animal
disease agent and eliminated a potential disease
risk to the equine industry. Unfortunately in this
incident, the source of infection could not be deter-
mined, so continued vigilance is necessary to detect
any potentially unidentified carrier animals.
Dual Infection of Racing Quarter Horses With Equine
Infectious Anemia and Equine Piroplasmosis Agent
In 2012, the Animal Health Branch of the California Department of Food and Agriculture began investi-
gating infections of EIA and EP in the California
racing Quarter Horse population. Since 2012, 39
racing Quarter Horses have been confirmed positive
for EIA and 21 racing Quarter Horses have been
confirmed positive to Theileria equi
, the causative
agent of EP. Ten of the positive horses had dual
EIA and EP infections. One of the dual-infected
horses was examined by a private practitioner who
had worked with state animal health officials on
treating a previously identified T. equi
infected
horse. The private practitioner contacted the
SAHO to report that she had examined a racing
Quarter Horse that had severe anemia. The
338 2016 fiVol. 62fiAAEP PROCEEDINGS
IN-DEPTH: INFECTIOUS DISEASE OUTBREAK MANAGEMENT