Strangles is an extremely infectious equine respiratory disease and can cause a major disruption in performance barns. It is caused by the bacteria Streptococcus equi ss equi (S. equi) and often causes abscesses to form in the lymph nodes of the head and throat area.
Young horses are more frequently affected, although horses of any age can contract the infection. Complications can include obstruction of the airway due to enlargement of the lymph nodes which may contribute to respiratory difficulty.
Quarter Horse News (QHN) talked with Dr. Angela Blackwell, of Horse & Hound Veterinary Clinic in Mooresville, Indiana, and Boehringer Ingelheim veterinarian Dr. Rob Keene, discussing five key points horse owners need to keep in mind regarding strangles.
1. Know the Signs and Act Accordingly
In a perfect world, horse owners should know what their horse’s normal vital signs are, especially its temperature. Dr. Keene recommends owners take the temperature of their horses on a regular basis and keep records in case their horse begins to show symptoms of illness such as not finishing its grain, lethargy, etc… Any temperature of 102 degrees Fahrenheit or more may indicate exposure to an infectious respiratory disease such as strangles.
In addition to fever, other signs of strangles can include a horse eating much slower than normal, due to having a sore throat, and nasal discharge, which may contain many infectious bacteria. Younger horses may be more prone to exhibit lymph node abscesses that can rupture.
According to Dr. Keene, horse owners should consult with their veterinarian on supportive care you can provide your horse if they contract strangles, as well as signs to watch out for which may indicate complications which can, but rarely, happen following a strangles outbreak.
2. Quarantine is Priority
As soon as a horse starts to exhibit clinical signs of strangles, the horse should be moved away from other horses.
“The biggest mistake owners can make is that they don’t quarantine once the disease is present,” said Dr. Blackwell.
According to Dr. Keene, nasal shedding of the bacteria usually occurs about 2-3 days after detection of fever. Shedding of the bacteria will usually last for 10-14 days, and on occasions as long as 6 weeks or longer. Horses should be quarantined for a minimum 10-14 additional days after clinical signs have resolved in an attempt to minimize the potential for shedding of the bacteria.
3. The Spread of Strangles is Swift
In a barn full of horses, the spread can spur a domino effect in a matter of days. Without proper quarantine of the infected horse, in as little as 3 days, horses that come in contact with the sick horse may become infected as well, If you have a barn of 20 horses, and it can take three days for each new horse to become infected, barn owners can have as many as 45-60 days of horses continuing to be sick as the disease spreads through the barn. During that time, the barn must stay closed with no traffic on or off the farm, said Dr. Blackwell.
In order for the barn to reopen, there must be a minimum of 10-14 days beyond the last horse showing any clinical signs before horses can be moved. The entire process can take months.
4. Strengthen Biosecurity Measures
Strangles is a disease spread either by respiratory droplets or orally, said Dr. Keene, and while the bacteria dies in a few days in the soil and on solid surfaces, it can be viable in water for up to 4-6 weeks.
“Common water sources, such as the water trough or buckets in an arena, can be the cause of the spread source in many strangles outbreaks,” said Dr. Keene. “Eliminating common water sources is good practice.”
Other biosecurity measures include having a buffer zone between pastures to prevent horses from touching noses with their neighbors and having individual tack and grooming supplies for each horse. Routine cleaning and disinfecting of feed pans and water buckets that travel from show to show is vital practice, as is keeping records of each horse’s temperature as they come and go from the barn.
5. Not Every Horse Needs the Vaccine
Not every horse should receive the strangles vaccine. If a horse was previously exposed to the S. equi bacteria in the past 12 months, giving the vaccine can be an invitation for purpura hemorrhagica, which a disease that affects both lymphatics and blood vessels which may occur after the horse was exposed to strangles.
If a horse was already exposed to the S. equi bacteria, they will have some degree of natural immunity from strangles. All horse’s immunity may be different. Performing an antibody titer on your horse prior to vaccination can give you and your veterinarian valuable information as to your horse’s immune system so you can proceed with vaccination protocols as needed.
While the inflammation of the lymph nodes and snotty noses may cause alarm, Dr. Keene stressed to owners to not to panic, as strangles is normally a recoverable disease and can be prevented with the right testing, vaccinations and biosecurity protocols.