Strangles in Horses by a Vet – 2025 Prevention, Diagnosis & Carrier Control Guide 🦠🐴
In this article
Strangles in Horses by a Vet – 2025 Prevention, Diagnosis & Carrier Control Guide 🦠🐴
By Dr Duncan Houston, BVSc
Introduction
Strangles is one of the most contagious and well-known respiratory diseases in horses. Caused by the bacteria Streptococcus equi, strangles spreads rapidly through barns and pastures—especially where young horses are kept. In 2025, vigilant biosecurity, carrier testing, and targeted vaccination strategies are the most effective ways to protect your herd.
What Is Strangles? 🧬
- Caused by Streptococcus equi bacteria
- Primarily affects horses under 5 years old
- Spread through nasal discharge or abscess drainage
- Highly contagious—especially in close-contact environments
How It Spreads 🚨
- Nasal shedding begins 4 to 16 days after infection
- Shedding typically lasts 2–3 weeks—but some horses remain carriers for months or years
- Contaminated water buckets, brushes, stalls, and human hands aid transmission
Carrier Horses: The Hidden Risk 🧪
- Some horses recover but continue shedding bacteria silently
- Bacteria hide in the guttural pouches of recovered horses
- These horses appear healthy but can reinfect the herd
Carrier Testing
- Three consecutive nasopharyngeal flushes with cultures
- PCR testing: highly sensitive, but detects dead or live bacteria
- Negative PCR = horse is likely clear; positive PCR = further culture needed to confirm carrier status
Symptoms of Strangles ⚠️
- Fever
- Thick nasal discharge
- Swollen lymph nodes under the jaw
- Difficulty swallowing or breathing
- Abscesses that may rupture and drain pus
Rare but Serious: Internal Strangles
- Bacteria spread internally to chest or abdomen (called “bastard strangles”)
- Blood titers help diagnose internal infections
- Usually not contagious, but life-threatening
Diagnosis 🩺
- Culture: confirms live Streptococcus equi
- PCR: detects DNA from dead or live organisms
- Blood antibody titer: useful for diagnosing internal abscesses
Strangles Vaccination 💉
- Intranasal vaccine preferred for strong mucosal immunity
- Best given to young, naïve horses before exposure
- Blood test first: horses with past exposure may react to the vaccine
Case Study: Foal Strangles Outbreak
- A 4-month-old foal presented with severe nasal swelling and difficulty breathing
- Emergency tracheostomy performed due to airway obstruction
- Postmortem confirmed guttural pouch abscesses from strangles
- The herd was quarantined for 30 days after the last case resolved
- Environmental disinfection and carrier testing were completed
Outbreak Control 🧼
- Immediate quarantine of sick horses
- Disinfect stalls, tack, buckets, and clothing
- Restrict movement of horses on and off the property
- Wait at least 30 days after the last horse recovers before lifting quarantine
Prevention Tips for 2025 🛡️
- Isolate all new horses for 3 weeks upon arrival
- Test new arrivals with PCR or nasal flush cultures
- Vaccinate young horses with the intranasal vaccine
- Clean hands, boots, and tools after handling different horses
FAQs About Strangles
Q: Is strangles contagious to humans?
A: No—Streptococcus equi does not infect people.
Q: Can a vaccinated horse still get strangles?
A: Yes—no vaccine is 100%, but it reduces severity and spread.
Q: How long should I wait before introducing a recovered horse back to the herd?
A: After 3 negative cultures or a negative PCR. Always consult your vet.
Conclusion
Strangles is highly contagious and often underestimated due to its frequency in young horses. While most horses recover, silent carriers and inadequate quarantine lead to recurring outbreaks. In 2025, the best protection includes early testing, effective isolation, and intranasal vaccination. If you suspect strangles, act fast to stop it before it spreads barn-wide.
Need help responding to an outbreak or preventing one? Visit AskAVet.com or download our app 📱 to consult Dr Duncan Houston and the infectious disease team for custom protocols. 🩺🐴
