Strangles in Horses: Symptoms, Quarantine, and Treatment
- See your vet immediately if your horse has fever, thick nasal discharge, swollen lymph nodes under the jaw, trouble swallowing, or noisy breathing.
- Strangles is a highly contagious bacterial infection caused by Streptococcus equi subspecies equi. It spreads through direct contact, shared water buckets, tack, hands, clothing, and contaminated surfaces.
- Quarantine matters. New arrivals are commonly isolated for 14 to 21 days, and horses on an affected property are usually separated into sick, exposed, and clean groups with strict biosecurity.
- Many uncomplicated cases are treated with supportive care, while antibiotics are reserved for selected situations such as severe fever, difficulty swallowing, breathing problems, or complicated disease.
- Some horses keep shedding bacteria after they look better. Your vet may recommend PCR testing of guttural pouch washes or a series of nasopharyngeal washes before release from quarantine.
What Is Strangles in Horses?
Strangles is a highly contagious bacterial infection of the upper respiratory tract in horses, donkeys, and mules. It is caused by Streptococcus equi subspecies equi and is best known for causing fever, thick nasal discharge, and painful swelling of the lymph nodes under the jaw and around the throat. Those lymph nodes often form abscesses, which is why affected horses can look dramatically swollen in the head and neck.
The disease is common worldwide and can spread quickly through a barn, boarding facility, training stable, or show environment. Young horses are affected often, but horses of any age can get sick. The incubation period is usually about 3 to 14 days after exposure, and fever is often the first sign your pet parent team may notice.
Most horses recover with appropriate care, but strangles can become serious. Swollen lymph nodes may interfere with swallowing or breathing, and some horses develop complications such as metastatic abscesses elsewhere in the body, immune-mediated purpura hemorrhagica, or long-term carrier status in the guttural pouches. That is why early isolation and a prompt call to your vet are so important.
Symptoms of Strangles in Horses
- Fever, often 102-106 F
- Thick nasal discharge that may become yellow or pus-like
- Swollen or painful lymph nodes under the jaw or throatlatch
- Abscesses that soften, rupture, and drain
- Depression, low energy, reduced appetite
- Difficulty swallowing or stretching the head and neck to breathe
- Noisy breathing, stridor, or increased breathing effort
- Cough or mild nasal discharge in partially immune horses
- Weight loss, persistent fever, or signs of internal abscesses
Fever is often the first clue, sometimes before the swelling becomes obvious. Within a day or two, many horses develop thick nasal discharge and enlarged lymph nodes under the jaw. As abscesses mature, they may rupture and drain. Some horses, especially older horses with partial immunity, can show milder signs that still spread infection.
See your vet immediately if your horse has trouble swallowing, noisy breathing, marked lethargy, prolonged high fever, or stops eating. Those signs can mean the swelling is affecting the airway or that complications are developing.
What Causes Strangles in Horses?
Strangles is caused by the bacterium Streptococcus equi subspecies equi. Horses usually become infected through direct nose-to-nose contact with a sick horse, but the bacteria also spread well on shared buckets, water troughs, feed tubs, tack, lead ropes, grooming tools, clothing, hands, and barn surfaces. Flies may also move bacteria mechanically during an outbreak.
One reason strangles is so disruptive is that apparently recovered horses can continue shedding bacteria for weeks. A smaller group become longer-term carriers, often because the bacteria persist in the guttural pouches. These horses may look normal but still infect others, which is why testing after recovery matters.
Risk rises when horses commingle with unfamiliar horses at shows, sales, clinics, racetracks, rescues, or boarding barns. New arrivals without a quarantine period are a classic setup for an outbreak. Stress, transport, and close housing do not cause strangles by themselves, but they can make spread easier once the bacteria are introduced.
How Is Strangles in Horses Diagnosed?
Your vet will start with the history, temperature, physical exam, and the pattern of illness in the barn. Fever plus swollen lymph nodes and nasal discharge often raises immediate concern, but testing is still important because other contagious respiratory diseases can look similar early on.
Diagnosis is commonly confirmed with bacterial culture or PCR testing. Samples may come from draining abscess material, nasopharyngeal washes, or guttural pouch washes. PCR is widely used because it is sensitive and can help identify horses that are still shedding bacteria.
In more complicated cases, your vet may recommend upper airway or guttural pouch endoscopy, ultrasound of the throat area, or additional imaging to look for hidden abscesses. Follow-up testing is often part of the plan before a horse returns to normal group housing, especially after an outbreak.
Treatment Options for Strangles in Horses
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call or haul-in exam
- Temperature monitoring and isolation plan
- Supportive care for uncomplicated disease
- Warm compresses to encourage abscess maturation
- Drainage-site flushing if advised by your vet
- NSAID plan if your vet feels it is appropriate
- Basic cleaning and disinfection guidance for buckets, tack, and stalls
Recommended Standard Treatment
- Exam plus farm call or hospital intake
- CBC and inflammatory bloodwork as needed
- PCR or culture from abscess material or nasopharyngeal wash
- Targeted supportive care and pain-fever control
- Antibiotics when your vet determines they are indicated
- Ultrasound of swollen lymph nodes or upper airway evaluation when needed
- Structured quarantine and retesting plan before release
Advanced / Critical Care
- Referral hospital care or intensive on-farm management
- Endoscopy of the upper airway and guttural pouches
- Guttural pouch lavage and targeted treatment for carrier state
- IV fluids, injectable medications, and nutritional support if needed
- Airway support for horses with severe throat swelling
- Imaging and workup for metastatic abscesses or purpura hemorrhagica
- Repeat PCR testing and extended biosecurity management
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Strangles in Horses
Bring these questions to your vet appointment to get the most out of your visit.
- Does my horse need immediate isolation, and how far should that isolation area be from other horses?
- Which test makes the most sense right now: PCR, culture, a nasopharyngeal wash, or a guttural pouch wash?
- Is this an uncomplicated case that may do well with supportive care, or are there signs that antibiotics are appropriate?
- What warning signs would mean my horse needs emergency care for breathing or swallowing problems?
- How should we divide the barn into sick, exposed, and clean groups during quarantine?
- When should we start retesting, and what results do you want before my horse can leave quarantine?
- Should other horses on the property have twice-daily temperature checks, and for how long?
- Is vaccination appropriate for this horse or this farm in the future, and when would it be safest to discuss that?
How to Prevent Strangles in Horses
Prevention starts with biosecurity. New arrivals should be isolated before joining the resident herd, and many equine guidelines recommend a 14- to 21-day quarantine period. During that time, monitor rectal temperatures daily, watch for nasal discharge or swollen lymph nodes, and avoid sharing buckets, tack, grooming tools, or handlers between groups unless clothing and equipment are cleaned first.
If strangles is suspected on the property, separate horses into affected, exposed, and clean groups right away. Use dedicated equipment for each group, disinfect surfaces, control flies, and limit movement on and off the farm. People who visit multiple horse facilities should change clothes and clean boots and hands before going elsewhere.
Vaccination can be helpful in some higher-risk situations, but it is not a one-size-fits-all answer. Your vet can help decide whether a strangles vaccine fits your horse's travel pattern, barn history, and outbreak risk. Vaccination during an active outbreak is generally not recommended because it may increase the risk of complications in some horses.
Finally, remember that prevention does not end when the fever is gone. Some horses continue shedding for 4 to 6 weeks after recovery, and a smaller number become longer-term carriers. Testing after clinical recovery, especially evaluation of the guttural pouches when indicated, is one of the most important steps in preventing the next outbreak.