Search Directory. Search Search. Recognized most for its signature symptom, strangles is a bacterial infection in horses similar to strep throat in humans. Are you familiar with how to spot less-obvious symptoms, treat, and prevent its spread?
By: Alisha Gruntman. Find out how researchers are working to develop better detection methods and vaccines for strangles. Infectious bacteria invade those glands, causing abscesses that swell until they burst into torrents of thick, yellow-green pus cascading from the nostrils or from beneath the jaw. And because the bacteria can survive away from the horse, outbreaks can be difficult to manage. Fortunately, researchers are making progress understanding strangles. Strangles has been around since at least the Middle Ages, when it was first described in a 13th-century text.
In fact, in the 19th century French emperor Napoleon Bonaparte I specifically ordered strangles-recovered horses for his cavalry. Streptococcus equi subspecies equi bacteria infect horses by settling in the lymph nodes in the head and neck, leading to swollen and painful abscesses. Horses usually get feverish, depressed, and lethargic and lose their appetite.
But many have less severe signs or none at all. Researchers believe horses that have endured an S. On the flip side, however, some horses become carriers, harboring the bacteria in their guttural pouches, a cavity at the back of the head, while appearing perfectly healthy. These horses can spread the disease agent silently wherever they go, possibly for the rest of their lives, Waller says.
Thanks to genomics research funded by The Horse Trust, a U. They can also test for S. These make carrier detection easier, allowing vets to treat and clear affected horses before they travel. The United Arab Emirates recently implemented such a screening program for horses scheduled for import, successfully blocking carriers and probably preventing new outbreaks in their territories, says Newton.
And their owners are busy people with packed schedules balancing work life with horse life. Managing strangles, and especially preventing it from spreading to other horses, requires a significant biosecurity effort, Boyle says.
A new study in collaboration with bioengineers at the University of Pennsylvania could lead to ultrafast results in the field, bypassing the need for a laboratory. Currently used to test for human infectious diseases in third-world countries where mail services are slow, the loop-mediated isothermal amplification LAMP method could make it possible to diagnose strangles before the veterinarian even leaves the farm. Our sources say it depends entirely on the situation.
For example, antibiotics might drag out the healing process—especially if abscesses have already formed. But that can lead to antimicrobial resistance bacteria becoming more drug-resistant , greater disease spread, and horses that get sick a few days later.
If the horse gets worse, antibiotics could be useful, she says. And some complications, such as Type III hypersensitivity a sort of allergic reaction to strangles, require both antibiotic and steroidal treatment. Strangles vaccines have been around since the early s, when Australian veterinarian Percival Bazeley vaccinated horses before they shipped off to war. The vaccine came with side effects, however—mainly painful and unsightly abscesses at the injection site.
Today veterinarians in North America and Australia have access to improved vaccines they can administer either IM or intranasally. But they require frequent boosters an initial series of three vaccines given two weeks apart, then at least annually , have moderate success rates, can cause complications such as abscesses in the case of IM injections , and run the risk of causing and spreading the disease itself, Newton says.
The incubation period for strangles is 3 to 8 days, at which point clinical signs, including lethargy, anorexia, fever, nasal discharge, and swollen lymph nodes with abscess formation may appear. Swollen, painful lymph nodes appear approximately one week after infection.
As the lymph nodes enlarge, they can cause respiratory obstruction as evidenced by labored breathing and difficulty swallowing, which can result in a loss of appetite.
Lymph node abscesses may rupture between seven days and four weeks after infection and typically drain through the skin or into the guttural pouches. Horses that are older and previously exposed generally have a milder form of strangles limited to upper respiratory signs, minimal to no lymph node abscesses, and a relatively fast recovery.
The sensitivity and specificity of diagnostic testing depends on several factors, including the stage of infection, sampling location and technique, and type of testing. Samples from the upper respiratory tract are obtained with nasal swabs, nasal washes, guttural pouch washes, or needle aspirate from an abscessed lymph node. Microbial culture can be used to detect S.
Testing takes approximately 1 to 2 days and is low cost and widely available. However, successful detection may be limited during early phases of infection. Quantitative polymerase chain reaction qPCR is faster results may be available on the same day and more sensitive, but does not distinguish between live and dead bacteria, so a positive result does not necessarily correlate with an active infection.
In complicated cases, an endoscopy of the upper respiratory tract may be required, as well as ultrasound and radiographs to identify the location and extent of abscesses. In most cases, strangles is treated with rest and supportive care. Horses are monitored closely to ensure pain management and adequate consumption of food and water. Antibiotics may be beneficial immediately after the onset of fever, prevent the formation of abscesses, and relieve airway obstruction, but their use is controversial because horses can have an altered post-infection immune response, which may leave them at risk for re-infection.
Antibiotic treatment may include penicillin, ceftiofur, or ampicillin. The appropriate use of antibiotics may shorten the course of the disease and prevent complications.
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