An Overview of Strangles in Horses
Strangles. The name of the disease itself can allude to a terrible demise, but most horses that contract strangles recover with minimal lasting effects. If youre lucky enough to have never had an outbreak at your barn, unfortunately chances are good you will be faced with one at some point.Table of ContentsToggleAn Age-Old Disease How Strangles Is Transmitted Among HorsesProgression of Strangles in HorsesTreatment of StranglesStrangles VaccineComplicationsShould Anyone Be Notified If Your Horse Has Strangles? Containing an Outbreak Key TakeawayPhoto by AK Dragoo PhotographyDiscover the transmission, progression, treatment and possible complications of one of the oldest equine diseases in the world.An Age-Old Disease Strangles was one of the first equine diseases to be described in 1251, says Katie Flynn, BVMS, Senior Staff Veterinarian-Equine Health & Biosecurity for the United States Equestrian Federation and former Kentucky State Veterinarian.Though nearly 775 years have passed, it still affects equines globally and remains one of the most diagnosed equine diseases in the world. In the United States, strangles is considered endemic, meaning its detected regularly in the horse population, says Flynn.If youve ever had strep throat, you can commiserate with a horse that has strangles; both infections cause enlarged lymph nodes in the head and neck. Strangles can affect horses of any breed or age, but older horses typically show more mild signs.How Strangles Is Transmitted Among HorsesThe Streptococcus equi bacteria that cause strangles are primarily transmitted through nose-to-nose contact with another horse, but the bacteria can also be transferred through feed, water, buckets, stall walls, veterinary instruments, clothes, grooming and barn tools, tack, and trailers.Nearly any surface can harbor S. equi for a time, which is why strict biosecurity protocols for ill horses are imperative.Whatever you touch has the potential to be contaminated, and if not cleaned and disinfected, can transfer the bacteria to a new horse directly or via someone elses hand to a new horse, says Flynn.Before panic ensues, its important to understand that S. equi can stay active in water buckets and moist areas for four to six weeks, but the bacteria can only survive for about one to three days in drier areas such as on fencing or in soil, says Flynn. Because the organism typically dies quickly in a sunny, dry environment, the usual source of infection is an infected horse, she explains.Similar to tracing the transmission of Covid-19, determining when exactly a horse got sickand from whomcan be nearly impossible. The time between a horses exposure to the bacteria and the onset of clinical signs can be anywhere from three to 14 days, says Flynn.Progression of Strangles in HorsesThough most horse owners associate a snotty nose as the first indication that a horse may have strangles (or another bacterial or viral disease), the first sign that something is amiss can actually occur 24 to 48 hours before in the form of a raised temperature.If the fever is caught before a horse develops a snotty nose, a strangles outbreak can be minimized if that horse is immediately isolated from all other horses. Its important to remember that an elevated temperature is when it goes up from that particular horses baseline, and not solely when the temp rises above the standard 101 degrees Fahrenheit.An elevated temperature (above 101 degrees Fahrenheit) can be the first clinical sign of a strangles infection. Photo by Sarah ColemanIf theres a jump, even if its still within the normal range, the horse should be moved to an isolation area, says Ashley Boyle, DVM, DACVIM, associate professor at the University of Pennsylvanias School of Veterinary Medicine New Bolton Center.As the disease progresses, so too will the horses clinical signs; his temperature will rise, often alarmingly. Thick, yellow nasal discharge is often seen, and the horse may have swollen lymph nodes under his jaw and around his throat latch.Thick, yellow nasal discharge is often a precursor to abscesses appearing in the throat latch area when a horse contracts an S. equi infection. Photo by Bob LangrishWhen the infection involves lymph nodes above the airway, horses adopt an extended neck posture and may cough, says Flynn. Other signs of illness can include poor appetite, foul-smelling breath, lethargy and loss of condition. A vet caring for a horse that is suspected of having strangles will perform a nasopharyngeal swab or a nasopharyngeal wash on the horse. The nasopharyngeal swab is extremely similar to a Covid test: A piece of cotton is passed up the nose, rubbed around the nasal passages, and sent for testing. A nasal wash is like a neti pot for horses; the vet will run a thin tube up the horses nose, flush sterile saline into the tube and catch what runs out the other nostril. This fluid is then tested.A polymerase chain reaction (PCR) test is the test most used to detect strangles; it detects S. equi bacterial DNA. Culturing the secretions is also a possibility, though this is not as rapid or as sensitive a form of testing.Some vets will perform a blood test to measure serum antibody levels, but this test is not useful in detecting current infection.However, paired serum samples taken two weeks apart can be useful in recognizing recent exposure, says Flynn.Treatment of StranglesThere is not much that can be done for a horse with strangles except supportive care while the infection runs its course.This may involve administering anti-inflammatories to lower body temperature or feeding the horse wet feed or hay from the ground. Feeding in this manner will make the food easier for the horse to swallow, as well as encourage abscesses to drain. A hot compress placed on abscesses can encourage them to burst.Hot compresses can help drain abscesses in the lymph nodes above the horses airway, but the disease generally must run its course. Photo by Sarah ColemanSome vets administer antibiotics to strangles-exposed horses as soon as they have an elevated temperature to prevent abscess formation. This practice is controversial, as the antibiotics may allow the horse to be re-infected with strangles the next time he is exposed.Strangles bacteria can hide in a horses guttural pouches, which are sacs of air located on either side of the horses head. These pouches are designed to cool the brain, ensuring that the blood near the brain is below the horses core body temperature, especially during exercise.A horse with strangles will need to have his guttural pouches scoped before he is considered free from the disease. Scoping involves threading a long, flexible rod with a camera up through the horses nose and examining the pouches. This flexible rod can also be used to administer antibiotics into the pouches if strangles bacteria is discovered.A horse must be scoped before he can be considered cleared of strangles; if S. equi is discovered, antibiotics can be delivered into the guttural pouches during the scope. Photo by Sarah ColemanA small basket can also be placed on the end of the rod to remove chondroids (dried pus) that may be found in the guttural pouches. A horse must be free of bacteria and chondroids, as well as have multiple negative nasal washes or nasal swabs, to be considered clear from the disease.Strangles VaccineThere are two types of strangles vaccines available: intramuscular (IM) injection, which is given like a traditional vaccine, and intranasal, which is misted up the nasal passage and provides mucosal protection, as well. Its important to remember that vaccine administration does not mean the horse will not get sick; it simply means that the horse will have less-severe disease presentation.I do not recommend that every horse get the strangles vaccine, said Boyle. The vaccine is really only needed by competition or trail horses that are regularly exposed to unfamiliar horses or for horses that live with horses that regularly travel, she notes.An intranasal vaccine is available for strangles, although vets do not recommend it for every horse. Photo by Bob LangrishHorses that have been exposed to a strangles outbreak should wait at least one year before theyre vaccinated with either the intranasal or intramuscular vaccine. Some horses immune systems can be overstimulated by the vaccine and the animal might develop purpura, says Boyle. Purpura hemorrhagica is swelling of the blood vessels in the head, neck and abdomen. Most cases are mild and are treated with antibiotics and corticosteroids.Its important that horse owners understand that vaccination alone is not effective, says Katie Flynn, BVMS, Senior Staff Veterinarian-Equine Health & Biosecurity for the U.S. Equestrian Federation. Vaccination may be an effective method of disease control in individual [horses] and herds when used in conjunction with a biosecurity plan. ComplicationsEquine strangles is a disease with a high morbidity rate, meaning many horses on a premises may become ill with the disease, explains Flynn. But approximately 98 percent of horses recover after several weeks in the acute phase of disease. Death due to strangles is not common.Inflammation associated with lymph node abscess formation and rupture may cause obstruction of the upper respiratory tract, hence the name strangles, she adds. Damage to the nerves near the abscess may result in the horse having difficulty breathing; further damage can make it difficult for the horse to eat.One of the scariest complications of strangles is its bastardization, where abscesses may occur in multiple sites, including the brain, abdomen and mammary glands. Additionally, cases of S. equi pneumonia have been known to occur. Should Anyone Be Notified If Your Horse Has Strangles? Strangles is considered a reportable disease in most states, meaning that the state veterinarian must be made aware of a positive test result (this is the responsibility of the testing laboratory or the veterinarian, not the horse owner). From there, the disease is classified as either reportable actionable or reportable monitored, according to Flynn.In the majority of states, strangles is reportable monitored, meaning no regulatory action is taken by state officials, but they do monitor the detections to determine if there is an increase or decrease in prevalence or a change in geographic distribution, she says. Very few states take regulatory action such as quarantine, testing and required biosecurity measures.There are multiple reasons why strangles may not be reportable actionable in a state. This can range from lack of state regulatory resources to do things like implement quarantine, the challenges associated with releasing a quarantine (and the testing that must take place to do so) or the states equine industry may not have requested or does not support enforceable action for the disease, says Flynn.The fact that the disease is not deemed actionable in many states should not in any way indicate that the disease is not serious, says Flynn. Strangles can pose significant risk to the individual equine, the herd, and the national equine population if proper biosecurity protocols are not followed.Containing an Outbreak There are three keys to containing a strangles outbreak, says Boyle. These are taking temperatures, isolating and separating.Any horse with strangles must be isolated. Avoid cross-contamination from hoses, buckets, manure forks and other equipment to avoid spread of disease. Photo by EdNurgAdobe StockThe ability to detect a sick horse by any deviation from his normal temperature will give farm owners 24- to 48-hour advance notice that the horse may have strangles. Once the horse is identified, if hes immediately moved (isolated) and separated from not only his neighbors, but also from staff who may interact with multiple horses, the likelihood of minimal farm impact increases.The isolation area need not be fancy, Boyle stressesit just needs to be effective.Even if its a shed thats got a gate to separate them, its better than nothing, she says. Even better would be to have a paddock as a barrier in between affected and unaffected horses.I deal with farms all the time that say, Well, everyone is exposed because I had one horse test positive, says Boyle. This truly isnt the case. Every horse may be minimally exposed, but I have successfully minimized outbreaks by immediately isolating the horse. The everyone is exposed mentality is not the way to goyoull deal with a much longer outbreak and have more horses with complications that may also turn into potential carriers afterward. What you do up front [to isolate and separate] can really limit the outbreak.In addition to being proactive about isolating horses that are sick or that may become sick, all other traditional biosecurity measures should be in place: not sharing buckets, tack or equipment; handling the ill horse last (and preferably by just one staff member), and paying scrupulous attention to details like ensuring hose ends arent dipped from bucket to bucket.Key TakeawayThough not often deadly, strangles presents a unique set of issues related to the ease with which its transmitted and the delay in symptom onset. Keen attention should be paid to all horses that travel off the farm and daily temperature-taking should be incorporated into every horses daily health check.This article about strangles appeared in the November/December 2023 issue of Horse Illustratedmagazine.Click here to subscribe!The post An Overview of Strangles in Horses appeared first on Horse Illustrated Magazine.
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