Strangles in Horses: Symptoms, Isolation, Biosecurity, Vaccination
- Horse Education Online
- 2 days ago
- 10 min read
Strangles spreads quickly because barns share water, handlers, and tack—and the first signs can look like “just a cold.” The difference is how fast fever and throatlatch lymph node swelling show up and how easily secretions move from horse to horse. This guide gives you the practical side: the early signs owners actually see, the first 24-hour isolation steps that limit spread, barn biosecurity that works in the real world, when and how testing clears quarantine, and where vaccination fits as a risk-reduction tool.
You’ll also find barn-side assets you can print and use today: our Strangles Isolation & Cleaning Checklist (PDF) to standardize setup and cleaning order, plus a landscape Daily Temperature & Symptoms Log (PDF) to keep AM/PM checks consistent during quarantine. Throughout, we’ll point to quick refreshers on checking vitals and vaccine context.
⚠️Important: this article is for education, not treatment instructions. Always loop in your veterinarian early, follow their guidance, and prioritize biosecurity.
TL;DR
What it is: Strangles is a contagious upper-airway infection caused by Streptococcus equi subsp. equi.
Top three actions (now):
Isolate the suspect horse immediately (separate water, tools, and handlers).
Call your veterinarian; ask about testing (PCR/culture) and quarantine planning for the whole barn.
Start logging temperatures and signs for all exposed horses; note travel/contacts.
Where vaccination fits: Risk-based and vet-guided. Vaccines can help reduce severity and limit outbreaks in appropriate horses/barns but are not an emergency “fix.” See our explainer on the 5-Way Equine Vaccine for context.
Vitals matter: A rising temperature is often the earliest red flag. If you’re unsure how to check, use The Horse’s Vital Signs quick guide.
What Is Strangles?
Strangles is a contagious bacterial disease of the upper respiratory tract caused by Streptococcus equi subsp. equi. The bacterium targets lymph nodes around the throatlatch (parotid/retropharyngeal), which can swell and sometimes form abscesses that drain. Horses often show fever, nasal discharge, dullness, and reluctance to eat, especially if swallowing is uncomfortable.
It spreads efficiently in barns because infected horses shed bacteria in nasal secretions and pus. Direct contact (nose-to-nose) and indirect contact (shared water, buckets, bits, halters, grooming tools, handlers’ hands/clothing, stall doors, hoses, trailers) are the main routes. It is not an “airborne” disease in the long-distance, measles-style sense; close contact and contaminated surfaces drive most transmission.
Some horses become temporary carriers (bacteria persisting in the guttural pouches) even after they look normal. That’s why testing and a structured quarantine plan matter before a barn “reopens.”
Education, not treatment: This guide explains recognition and biosecurity. Your veterinarian will advise on diagnostics, quarantine length, and care decisions for your specific barn.
Strangles at a Glance
Aspect | Key points |
Causative agent | Streptococcus equi subsp. equi |
Typical early signs | Fever, nasal discharge, enlarged throatlatch lymph nodes, dullness, off feed |
Incubation period | ~3–14 days from exposure (often 3–10) |
Main transmission | Direct contact; indirect via water, tack, tools, hands, clothing, trailers |
“Airborne”? | No long-range airborne spread; close-range droplets/fomites dominate |
Environmental survival | Variable; moisture/organic matter prolong survival—clean, then disinfect |
Carriers | Possible (guttural pouch); testing helps clear quarantine safely |
Who to involve | Your veterinarian (diagnostics, quarantine, reopen criteria) |
Early Signs Owners Actually See
Common early signs
Fever (often the very first clue)
Nasal discharge that becomes thicker/yellow
Swollen glands at the throatlatch (parotid/retropharyngeal lymph nodes)
Dullness and off feed; sometimes cough or difficulty swallowing
Reluctance to lower the head (pressure discomfort)
Strangles can look like a “simple cold” for a day or two. The difference is how quickly fever and lymph node swelling appear, and how contagious the horse becomes to herdmates via nose contact, shared water, and handled gear.
Taking and logging vitals (what numbers mean)
Start barn-wide checks for any horse that shared a fenceline, water source, trailer, or aisle within the last 2 weeks.
Vital | Normal adult | Act-now thresholds (call your vet) | How often to check (exposed) |
Temperature | 99.0–101.0 °F (37.2–38.3 °C) | ≥101.5 °F (38.6 °C) or a 0.5–1.0 °F day-over-day rise | 2× daily |
Heart rate | 28–44 bpm | Persistent >48–52 bpm at rest with other signs | 1–2× daily |
Respiratory rate | 8–16/min | >24/min at rest with effort/noise | 1–2× daily |
If you need a refresher on technique and full ranges, see our quick guide to The Horse’s Vital Signs (already linked above).
To interpret heart rate, use Average Heart Rate for a Horse and compare to your horse’s baseline.
For broader red flags that cluster with strangles (lethargy, dehydration, behavior change), review How to Tell if Your Horse is Sick.
Practical tips
Thermometer: label one “Isolation Only.” Use a dab of petroleum jelly; stand to the side of the hip.
Same times each day: e.g., 7 a.m. and 7 p.m. Fever patterns matter.
Note context: shavings stuck to nasal discharge, reduced hay intake, unusual barn traffic—all help your vet reconstruct exposure.
First 24 Hours: Isolation & Communication
Immediate isolation (do this now)
Move the suspect horse to a separate stall or paddock with a physical gap from others.
No shared water: dedicated bucket/tub; never dip a communal hose into any bucket.
Dedicated tools: label a pitchfork, broom, muck bucket, and thermometer for that horse only.
Handler rules: one handler if possible; handle isolated horses last, then shower/change clothes.
Door/signage: “Isolation—No Entry. Dedicated Gear Only.”
Example layout: If stalls are tight, use the end stall with a solid door, place a small table for PPE and hand sanitizer outside, and run a one-way aisle flow (entry on one end, exit the other) during chores.
Who to call and what to share
Veterinarian: report temps, first signs, travel/events in the last 2–3 weeks, and the exposure list (neighbour stalls, pasture mates, shared trailers, lesson horses). Ask about PCR/culture testing and quarantine scope.
Barn manager/owners: align on movement restrictions, cleaning cadence, and a single point of contact to reduce mixed messages.
Haulers/visitors from the last 14 days: notify that an investigation is underway; advise them to monitor temps at home.
Template snippet (copy/paste):“We’ve isolated one horse for suspected strangles. Vet has been contacted. Please monitor temperature twice daily and avoid shared water/gear. Use assigned tools only and handle the isolated area last. Awaiting vet guidance on testing and quarantine duration. Thank you for following biosecurity signs and traffic flow arrows.”
Start a temperature log and symptom tracker
Begin today for the suspect horse and any exposed horses.
Mini log (example for one horse):
Date | Time | Temp (°F) | Nasal discharge | Gland swelling | Appetite | Notes/contacts |
10/07 | 07:00 | 101.7 | Clear | Mild left | ↓ | Stabled next to #12; shared hose 10/05 |
10/07 | 19:00 | 102.3 | Thick/yellow | Larger L/R | ↓ | Isolated; labeled tools set |
Download the Daily Temperature & Symptoms Log (PDF).
Record AM/PM temps, heart and respiratory rates, and key signs for 30 days. Keep everyone aligned during quarantine with one simple, printable sheet.
Barn Biosecurity That Actually Works
Personal protective habits
Keep germs off your hands, clothes, and boots. Handle isolated horses last, then wash up and change.
Simple routine (repeat every visit)
Wash or sanitize hands before and after each horse.
Wear disposable gloves in isolation; toss before leaving the area.
Keep a “barn jacket” and rubber boots for the isolation zone only; hose boots, then scrub soles.
Bag dirty towels/sheets separately; launder hot, full dry cycle.
Note: Insect control isn’t the main defense for strangles, but clean aisles and good manure management help overall barn hygiene. If you’re reviewing summer hygiene, see our Fly Spray Guide.
Equipment segregation
Don’t let buckets or tack become “delivery trucks” for bacteria.
Label and park gear
Use colored tape or a marker: “Isolation Only.”Buckets, tubs, hoses, thermometers, pitchforks, halters, lead ropes, bits, grooming kits, and coolers all get their own set.
Keep them in the isolation zone. Store the communal hose nozzle above buckets so it never dips into water.
Cleaning and disinfection cadence
Cleaning removes organic matter; disinfection kills what’s left. Do both—in that order.
Daily rhythm
Clean first: Scrub items with detergent and water to remove debris.
Then disinfect: Apply a vet-recommended disinfectant to pre-cleaned surfaces; follow the product’s contact time.
High-touch points: Stall doors, cross-ties, gates, latch handles, wheelbarrow grips—wipe after each chore run.
Trailers: Treat floors, walls, chest bars, tie areas after any exposed horse use.
Let surfaces dry before reuse. Moisture + organic matter reduces disinfectant power.
Manure and traffic flow
Keep people and horses moving in one direction to avoid backtracking bacteria.
Simple layout
Post one-way arrows down aisles during chores.
Park isolation manure carts outside the common path; dump last.
Walk healthy horses first, exposed next, isolation last.
Stage hay and bedding outside the isolation zone to limit cross-traffic.
Barn-Side Isolation & Cleaning Checklist (PDF)
Download the barn-side checklist to set up isolation fast, label gear clearly, and run a clean-then-disinfect routine that actually works. Print it, post it on the stall door, and brief the team in two minutes.
Testing, Quarantine Length, and When It’s Safe to Reopen
Vet diagnostics overview
Your veterinarian will choose tests based on barn goals and stage of disease.
The common options
PCR (nasal or guttural pouch): detects bacterial DNA; fast and sensitive.
Culture: grows the organism; confirms live bacteria and aids outbreak mapping.
Carrier checks: Endoscopy with guttural pouch sampling can find seemingly normal shedders.
Expect your vet to decide who to test (sick horses, close contacts, returning travelers) and when (acute phase vs. clearance testing).
How long to quarantine
Plan for weeks, not days. Quarantine length depends on signs and test results.
Practical framework (vet-guided)
Symptom-based: Keep a horse in quarantine until afebrile, eating normally, and nasal discharge has resolved.
Test-based exit: Many barns require two to three negative PCRs (often 1 week apart) before lifting restrictions—your vet will set the exact protocol.
Barn-wide timing: The clock usually resets with each new case; expect staggered release dates.
Track every horse’s last fever date and test dates in the log so the whole team can see progress at a glance.
Reintroducing horses and gear safely
Come out of quarantine deliberately to avoid a relapse in barn operations.
Step-wise return
Horse first, then hardware: Reintroduce the horse after clearance; disinfect and re-label any isolation gear before it rejoins common storage.
Soft landing: Resume turnout or light hand-walking per vet guidance; keep the horse on separate water for a few extra days while you watch for late signs.
Debrief: Hold a 10-minute team review—what worked, what to improve—so your barn’s SOP gets stronger for next time.
⚠️Your veterinarian is the final word on testing choices, quarantine length, and reopening steps. Our job is to keep records clean, movement orderly, and biosecurity tight so the plan works.
Vaccination: Role, Timing, and Conversations With Your Vet
Where vaccination fits
Vaccination can reduce severity and shedding in at-risk horses and help limit future barn outbreaks. It’s most useful for travel/show barns, lesson strings, and facilities with frequent new arrivals. It’s not an emergency cure during an active case; decisions are risk-based and vet-guided.
Talk through these with your vet
Your barn’s exposure profile (shows, clinics, sales, new boarders).
Each horse’s history (prior strangles, vaccine reactions, age, health).
Product type and route (intranasal vs IM) and how that affects scheduling and handling.
For broader context on multi-antigen programs and timing alongside core risk, see 5-Way Equine Vaccine—What It Covers and Why It Matters.
Timing around outbreaks
Vaccinating into an active outbreak is nuanced. Your veterinarian may delay certain horses, prioritize others, or use targeted strategies for cohorts with similar risk. The goal is to avoid creating heavy traffic through isolation areas and to sequence biosecurity, testing, and vaccination so they don’t work against each other.
Practical barn examples
Show team due next month: Vet may schedule vaccination after the quarantine plan is set and movement is stable.
New boarders: Consider a pre-arrival vaccine policy plus staged introduction and temp logs.
Large lesson barn: Map the herd into zones and vaccinate zone-by-zone outside isolation to keep flows clean.
Bottom line: treat vaccination as part of a prevent-and-contain plan, not a same-day fix. Your vet’s timing is the blueprint.
Nutrition, Hydration, and Comfort During Recovery
Keep eating easy
Sore throat and enlarged lymph nodes can make swallowing uncomfortable. Offer palatable forage and, if advised by your vet, soft, soaked feeds so intake stays steady.
Simple adjustments
Fresh, leafy grass hay over stemmy lots.
Soak pellets/cubes into a wet mash for easier swallowing.
Keep salt available; flavor water with a splash of the barn’s regular electrolyte water if the horse is picky.
For balanced rations during downtime, skim The Basics of Equine Nutrition and match to what your horse will reliably eat.
Hydration and electrolytes
Fever and off-feed days can reduce water intake. Track bucket volumes and encourage drinking with familiar tubs and temperature-neutral water.
Quick checks
Aim for steady urine output and normal, moist gums.
Offer two buckets (plain + lightly flavored) to nudge intake.
Use our Salt & Electrolyte Calculator to estimate daily needs when your vet recommends supplementation.
Comfort and routine
Quiet routines lower stress and help you spot changes early. Keep the horse near barn activity but separate, maintain consistent feeding times, and note attitude, manure, and appetite in your log.
Light movement (⚠️vet-approved only)
Hand-grazing or short hand-walks may be appropriate only if your veterinarian approves and biosecurity is maintained (separate path, separate halter/lead, wipe hands afterward).
⚠️Reminder: These are owner basics for comfort and monitoring—not treatment instructions. Your veterinarian guides all care decisions, including any feed changes or electrolyte use.
Conclusion
Strangles moves fast, but your plan can move faster: isolate first, loop in your vet, and run clean-then-disinfect on a tight cadence. To make that easy, print our Strangles Isolation & Cleaning Checklist (PDF) and post it on the stall door. Keep temp logs, label gear, and handle isolation last—every time.
If you want all the barn-side tools (including the 30-day Temperature & Symptoms Log) plus printable study aids, join Memberships and explore our equine study materials (flashcards and posters). For deeper learning and reference, browse our Books.
Round out your SOP with quick refreshers: The Horse’s Vital Signs, Average Heart Rate for a Horse, How to Tell if Your Horse is Sick, and vaccine context in 5-Way Equine Vaccine—What It Covers and Why It Matters. Support recovery basics with The Basics of Equine Nutrition and our Salt & Electrolyte Calculator. When you’re tightening overall barn hygiene, our Fly Spray Guide and full Tools hub help keep routines consistent.
Vet-first decisions, clear checklists, and steady communication—that’s how barns contain strangles and get safely back to work.
FAQs: Strangles in Horses
Is strangles airborne or mostly spread by contact?
Strangles spreads mainly by close contact and contaminated items—nose-to-nose, shared water, tack, buckets, grooming tools, hands, clothing, trailers. It isn’t “long-range airborne” like measles. Keep distance, segregate gear, and wash hands to cut most transmission.
How long is a horse with strangles contagious?
Contagiousness starts before obvious swelling and can last weeks. Some horses become temporary carriers that shed bacteria even after they look normal. Your vet may recommend PCR/culture and, if needed, guttural pouch checks to confirm clearance.
What’s the minimum quarantine period and how do we exit safely?
Plan on several weeks, guided by your veterinarian. Many barns use symptom resolution plus two to three negative PCR tests (often a week apart) before reopening. The barn clock often resets with each new case, so track dates carefully.
Do recovered horses become carriers?
Some do, temporarily. Bacteria can persist in the guttural pouches. Carrier checks and, when indicated, vet-directed procedures help clear them. This is why test-based exit criteria matter before lifting restrictions.
Can vaccination stop an outbreak already underway?
Vaccination is a risk-reduction tool, not an emergency fix. During an outbreak, your vet will time vaccination carefully—or defer for some horses—to avoid disrupting isolation/testing plans. Long term, vaccination can help reduce severity and shedding in at-risk herds.
What should we disinfect—and how often?
First clean to remove dirt and organic matter; then disinfect pre-cleaned surfaces. Hit high-touch points (stall doors, latches, cross-ties, gate chains, wheelbarrow handles) after each chore run. Buckets, tubs, bits, halters, grooming tools, and trailers should follow a clean → disinfect → dry routine.
When can my horse go back to light work?
Only when your veterinarian clears it. Many horses resume light activity after fever and nasal discharge resolve and quarantine/testing milestones are met. Start gradually, keep biosecurity in place, and continue daily monitoring.
