What is Strangles? Strangles is a contagious bacterial infection in horses
caused by the bacteria
Streptococcus equi subspecies
equi. Occasionally the related bacteria
Streptococcus equi subspecies
zooepidemicus causes clinical signs in horses
similar to those seen in Strangles, although this second
bacteria is also found on healthy, normal horses and in
other species like cows.
Clinical Signs. Clinical signs
of Strangles include fever, yellow or green
nasal discharge, abscessed lymph nodes around the throat, and
occasionally more severe internal illness and death in
Transmission Between Horses.
The bacteria can spread easily through a stable.
It is transmitted by direct nose-to-nose contact between
horses. Healthy horses may become infected when
they lick or chew fencing or rails contaminated by the
nasal and abscess discharge from sick horses.
Flies help spread the bacteria by landing on the nasal
discharge or open abscesses of a sick horse then landing
on the nose of a healthy horse. People may spread
the bacteria on their hands by touching sick horses and
then healthy horses. People also spread the
infection between horses when they use the same buckets,
grooming material, and other equipment for both healthy
and sick horses. Strangles can be introduced into a
stable when new horses carrying the infection are
brought into the stable. Resident horses that
travel outside the stable for training or events may
bring the infection back home when they return.
Transmission to Humans. In
rare cases, humans have contracted infections from the
bacteria that cause Strangles. To prevent human
infection, people caring for horses with Strangles
should avoid getting any nasal or abscess discharge from
the horse on their eyes, nose, or mouth. The
should also wear disposable gloves while working with
the horse, avoid touching their face, and should wash
their hands thoroughly when finished.
Diagnosis and Treatment.
Strangles cases should always be seen by a veterinarian.
The veterinarian may perform a culture to diagnose the
bacteria, may prescribe antibiotics, and will
likely recommends frequent cleaning of abscesses.
The sides and edges of the stall should be cleaned and
disinfected daily to prevent dried nasal and abscess
discharge from accumulating. Any gauze or other
materials used in cleaning abscesses and nasal discharge
must be disposed of in a covered or sealed trash
receptacle, to prevent flies from landing on it. The
infected horse should be isolated from healthy horses.
Horses that recover completely are usually immune to the
bacteria for many years afterward. However, up to
10% of horses that appear to be recovered may still
carry the bacteria and spread it to others for prolonged
periods (i.e. become "carriers").
Prevention. Stables should
have a designated quarantine area in which new arrivals
are placed for 3
weeks and observed for symptoms. This quarantine
area needs to have its own, dedicated equipment for
caring for the horses (buckets, brushes, feed area,
equipment for mucking out) so that contaminated
equipment is not used on healthy horses in the rest of
the stable. Ideally new horses are screened
for Strangles. Vaccines against strangles are available and can help
greatly in reducing the severity of illness, should the
horse get infected. In certain
cases, vaccines against strangles may be
contraindicated. Consult with your horse's
veterinarian to decide if vaccination against strangles
is needed for your horse.
Strangles in Los Angeles County.
Three Strangles outbreaks were reported in Los Angeles County
between 2004-2008. It is likely to be
Strangles Myths. Misinformation about strangles has
been encountered during outbreak investigations.
Common examples include: the belief that Strangles
infections are never serious, the belief that Strangles
infections are unavoidable, and the belief that humans
cannot become infected with Strangles. All
are false. Deaths of horses have been
reported in at least 2 Strangles outbreaks in Los
Angeles County. Proper stable management and sanitation
can reduce the risk of Strangles infections
considerably. Human infections with Strangles,
although not common, do occur.
Reporting. Outbreaks of strangles are reportable in Los Angeles
here to download the pdf of the form for reporting
Association of Equine Practitioner's webpage on
American College of Veterinary Internal Medicine' 2005
Consensus Statement on Strangles
Equine Strangles FAQ (pdf)
Strangles in the Antelope Valley 2007
Links to scientific articles on human cases
2003 - Streptococcus equi subspecies equi (Lancefield
group C) meningitis in a child
2006 - Post streptococcal acute glomerulonephritis
secondary to sporadic Streptococcus equi infection
2004 - Primary purulent pericarditis due to group C