Strangles
Infection
"Strangles"
is a layman's term for Streptococcus equi infection. It is an
extremely contagious bacterial infection which is contracted through
the mucous membranes your horse’s nasal/ oral passages.
Strangles
can be fatal, but this is rare. Usually, infection remains localized
within the upper respiratory system. Because bacterial inoculation
occurs in the mucous membranes of the nasal and oral passages,
it occasionally "seeds" in the intermandibular lymph
nodes, which often become swollen and painful. "Bastard
strangles" is a layman's term which describes mobilization
of the bacteria from the intermandibular lymph nodes to other
parts of the body. Depending on where (and how many places) bacteria
end up, the disease may become life-threatening.
Antibiotic
therapy in the form of Penicillin can be used to alleviate clinical
signs in severe cases. However, because strangles is caused by
a tough, gram-positive bacteria, indiscriminate use of antibiotics
can cause the disease to linger in horses for extended periods
of time. Therefore, it is generally better to let
the infection run its course and treat only when necessary…it
will resolve much quicker.
Once the first horse
exhibits clinical signs of strangles, one should assume that EVERY
horse in the barn has been exposed. All horses should have their
temperatures taken twice a day, since a rise in body temperature
of 1.5°F over normal is an indicator that the horse might
contract the disease. Horses with fever should be isolated immediately.
Since normal-appearing
horses may be incubating the disease, we highly recommend
not moving horses around, to, or from the premises. If possible,
visibly affected horses should be strictly isolated to allow for
more intensive care and discourage direct transmission to other
horses.
Factors that
facilitate transmission of strangles infection include human hands,
shoes, clothing, towels, grooming equipment, flies, and anything
else that touches discharge from a sick horse, then lands on a
healthy horse's nose. The bacteria can persist in the environment
for a variable amount of time, especially when protected by discharge
material. Contaminated bedding should be disposed of properly
and not spread on pastures, since it also can be a source of contamination.
In regard to vaccination,
the intranasal preparation is by far the best to use, because
it elicits a local (and dramatic) immune response within the mucous
membranes of the oral and nasal passages (where the disease is
contracted) rather than a general systemic response (which occurs
pursuant to intramuscular vaccination). However, we would not
expect any strangles vaccine to provide complete protection. This
is because...
- Vaccines
are generally designed to prevent VIRAL infection. Viral
antigens are extremely
specific and consistent from one animal to another. Vaccinating
against rabies, for example, pretty much assures that rabies
infection
won't occur. Bacteria, on the other hand, have many strains.
Although you may elicit a general (broad spectrum) response
against a certain
type of bacteria, the response is not nearly as specific
for any one strain.
- During
an epidemic, your horses have (undoubtedly) already been
exposed to strangles.
Vaccinating now will not elicit enough of an immune response
to provide much (if any) protection.
Nevertheless, we recommend
vaccinating all potentially-exposed horses (with the intranasal
preparation) including the pregnant mares. Because the vaccine
contains live bacteria, care must be taken in terms of administration.
The vaccination process should be the very last thing that is
done on the farm that day. Hands should be washed in between every
horse. DO NOT administer any intramuscular injections to horses
that have been vaccinated within the past 24 hours. Your clothes,
shoes, and body should be washed thoroughly after handling horses
with strangles.
There is no disinfectant
that can be safely used on pastures. Water and feed buckets should
be daily cleaned with a detergent and disinfected with a phenolic
disinfectant, then thoroughly rinsed prior to use.
We
highly encourage you not move any horses off or onto the grounds
until AT LEAST 30 days AFTER THE LAST HORSE'S SYMPTOMS HAVE
COMPLETELY RESOLVED. This sounds like a long time,
but the infection can linger in asymptomatic horses for many months.
Prior to moving horses, EVERYTHING the horses come in contact
with in the barn (bridles, halters, stalls, aisle ways, etc.)
should be disinfected with bleach solution. Let dry for 24 hours.
If you have any further
questions or concerns regarding strangles infection, please call
our office to speak with one of our veterinarians.
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