STRANGLES
What you need to know..!!
There are over 500 outbreaks of Strangles each year in the UK. These can
involve all of the horses/ponies in the yard and require strict movement
restrictions that may go on for more than 8 weeks. There is a considerable
financial implication. Strangles is spread by direct or indirect contact with
sick horses or apparently healthy carrier horse/ponies and not through the
air like equine flu.
If direct or indirect contact with infection can be avoided then the
disease will not spread.
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The germ which causes Strangles is called Streptococcus Equi.
It has the ability to establish persistent infections usually within the
`guttural pouches` [part of the middle ear]. The live bacteria can reside
here for long periods and may be shed from time to time in nasal
discharges and saliva. Horses and ponies which have these infections
are called `carriers`. It is these carriers which are responsible for
keeping the germ alive and starting new outbreaks of Strangles.
Carriers can be reliably detected with a blood test which will identify
horses that have recently been in contact with the disease or are
currently carrying it without exhibiting any symptoms.
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Carrier individuals are resistant to infection and appear healthy. For
this reason new horses coming on to a closed yard should be
quarantined for 14 - 21d and assessed properly before mixing with the
other horses and ponies.
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Carriers can be treated but it`s not straightforward and is costly.
Symptoms include:
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Fever [often a very high temperature and a very sick horse/pony.]
Very sore throat - often standing with neck extended and reluctant to
eat.
Visible abscesses in lymph nodes around head and neck
A yellow purulent discharge from the nose caused by pus draining
from ruptured internal lymph node abscesses.
In mature horses however, the symptoms may take a milder form and
be less obvious.
Recovery:
Most horses/ponies [98%] recover over a few weeks. About 10% of horses
fail to clear all abscess material from their `guttural pouches` [GP= part of
the middle ear] and sinuses. These individuals become carriers
[intermittently shedding live bacteria] for a varying length of time up to and
including the rest of their lives. These bacteria can be spread to other
uninfected horses in shared drinking water, on tack, head-collars, coat
sleeves etc.
Treatment:
The disease is sensitive to antibiotics especially penicillin. Treatment with
antibiotics will improve the symptoms of sick horses but may extend the
time taken to resolve the outbreak overall. Treatment of mildly affected
horses or horses incubating the disease may reduce the immune response
and result in them not developing the antibody levels they should do. It`s
probably best to reserve antibiotics for sick horses that really need
treatment.
Prevention:
There is a vaccine available but it has some issues associated with its use.
The vaccine is administered into the mucous membrane of the top lip and
can cause local reaction. Many horses develop a fever after administration.
The resulting antibodies are identical to those produced by the disease itself
and will confuse the interpretation of strangles blood test results. The
vaccine has to be administered 4x yearly to be really effective. On balance
it`s probably not worth vaccinating in most situations at present. I wouldn’t
vaccinate my own horses. The development of a truly safe, effective vaccine
has eluded scientists so far.
Prevention is achieved by correct management
Direct contact between infected horses is the most obvious means of
transmitting the infection but the hands and equipment of staff, farriers or
veterinary surgeons can spread it indirectly. The bacterium is discharged
(shed) from draining abscesses and the nose, and it may survive in the
environment, particularly in water troughs. Each horse should ideally have
its own water bucket, feed bowl and hay nets. Good hygiene is essential in
preventing the spread of the disease.
Ideally, all horses entering any stud or stable premises should be
quarantined for a period of 2-3 weeks and monitored closely, particularly in
the period immediately after arrival. Any horse that develops a nasal
discharge or other signs consistent with strangles should be isolated and
tested for the presence of, or exposure to Strangles.
The Strangles blood test can be used to identify horses that have elevated
antibody responses to Streptococcus Equi and have been exposed to this
germ in the recent past or are carriers, enabling the identification of
potentially infectious animals as soon as is possible.
Yards where infection has been diagnosed or who are being investigated
should remain closed. Individuals from these yards shouldn’t attend equine
events until they have been cleared to do so. Unaffected horses which have
been isolated and are under observation may exercise locally preferably at a
time when they won`t meet other riders.
Owners of horses in affected yards and their staff shouldn`t be in contact
with other horses/ponies without changing their outer clothing and washing
their hands.
When out hacking or at an event avoid direct contact with horses from other
yards. You won`t catch Strangles if you keep your distance!
Any questions please feel free to post on Thornton Equine Facebook
page.
Nick Bowen Cert EP MRCVS 14/05/15