HORSES · Condition guide
Strangles in horses: real veterinary case reports
Strangles is the highly contagious bacterial respiratory disease caused by Streptococcus equi subsp. equi. It's one of the most commonly diagnosed infectious diseases in horses worldwide and remains a serious biosecurity problem for yards, sales, and competition centres. Classic signs are sudden fever, off feed, nasal discharge progressing from clear to thick yellow, and the characteristic enlargement and abscessation of the submandibular and retropharyngeal lymph nodes — which can rupture and drain pus.
Most healthy adult horses recover fully with supportive care alone; routine antibiotics are not recommended for typical uncomplicated cases. Two important complications: "bastard strangles" (metastatic abscessation in other body locations — much more serious), and purpura haemorrhagica (immune-mediated vasculitis). Up to 10% of recovered horses become long-term carriers via persistent infection in the guttural pouches (chondroids), and these silent shedders are how outbreaks restart at yards.
What vets typically check for
- Clinical signs + nasopharyngeal swab or wash for PCR (most sensitive) and culture.
- Endoscopy of guttural pouches and nasopharynx — identifies chondroids or empyema.
- Serology (SeM antibodies) — screens for prior exposure and identifies carriers.
- Supportive care: hot-pack abscesses, ensure soft palatable feed, isolate from other horses.
- Strict biosecurity protocol — three negative guttural pouch washes before release from isolation.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Strangles in horses (Streptococcus equi). Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- Reining in strangles: Absence of disease in horses vaccinated with a DIVA-compatible recombinant fusion protein vaccine, Strangvac, following natural exposure to Streptococcus equi subspecies equi.
Equine veterinary journal · 2026
A group of 17 healthy horses was vaccinated with a new vaccine called Strangvac after an outbreak of strangles, an infectious disease caused by Streptococcus equi. The horses were monitored for signs of illness, and none of them developed strangles, even though some showed evidence of exposure to the bacteria. Blood tests indicated that all vaccinated horses produced antibodies
- Zoonotic aortic graft infection by Streptococcusequi.
Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy · 2026 · Japan
A 69-year-old woman with high blood pressure had surgery seven years ago to replace part of her aorta with a stent graft. She went to the hospital because she had a fever and a cough. Tests showed that her aorta was enlarged and there was fluid around the graft, which suggested an infection. Blood tests revealed that she had an infection caused by a type of bacteria called Stre
- Updates on Diagnosis and Treatment of Guttural Pouch Conditions.
The Veterinary clinics of North America. Equine practice · 2026 · United States
The guttural pouch is a special part of a horse's anatomy that can sometimes cause health problems. Recent advancements in surgery, special tools, and medications have made it easier to treat conditions affecting this area, like fungal infections, fluid buildup, air accumulation, and joint issues. New guidelines also help veterinarians diagnose and manage infections caused by a
- Headshaking associated with a unique presentation of guttural pouches infection and otitis media in a Quarter Horse stallion: diagnosis, medical treatment and outcome.
Journal of equine veterinary science · 2025 · Italy
A 3-year-old Quarter Horse stallion was brought in for headshaking that had been happening for a month. The vet found inflammation in the horse's guttural pouches, which are located near the throat, and identified a bacterial infection. The horse was treated with antibiotics and anti-inflammatory medications, and after two months, the headshaking had stopped, and he was able to
- Traumatic brain abscess due to Streptococcus equi subspecies zooepidemicus in a Foal.
Veterinaria italiana · 2025
This report discusses a rare case of a 3-month-old female Quarter Horse that developed a brain abscess, which is a pocket of infection in the brain, caused by a bacteria called Streptococcus equi subspecies zooepidemicus. The foal showed signs of seizures, seemed very tired and depressed, and was blind in both eyes. A special imaging test called a CT scan revealed a large area
- Histopathological and diagnostic aspects of glanders based on a case series from Brazil.
Journal of equine veterinary science · 2025
Glanders is a serious disease that affects horses and is caused by a bacterium called Burkholderia mallei. In this study from Brazil, researchers looked at 16 adult horses and one fetus that were found to have glanders during outbreaks. They discovered that while some horses showed signs of illness, like respiratory issues, others did not show any symptoms at all. The researche
Frequently asked questions
- Should I give antibiotics?
- Counterintuitively, routine antibiotics are not recommended for typical cases — they don't shorten the course, may interfere with normal abscess maturation, and can predispose to bastard strangles. Antibiotics are indicated for severe cases, complications, and certain prophylactic situations under veterinary direction.
- How long is a horse contagious?
- Shedding usually begins 1-2 days after fever onset and continues 2-3 weeks after clinical recovery. Up to 10% of recovered horses become silent carriers via the guttural pouches and can shed intermittently for months or years — three negative guttural pouch washes are the gold standard before declaring a horse non-infectious.
- Will the vaccine prevent it?
- Available vaccines (intramuscular and intranasal modified-live) reduce severity but do not reliably prevent infection. Strict biosecurity — quarantine of new arrivals, isolation of febrile horses, dedicated equipment, footbaths — is the most effective control on most yards.