Strangles in Horses in New Zealand: Signs, Spread and Prevention

A practical guide for every New Zealand horse owner

Strangles in horses is a highly contagious bacterial infection. It is not a virus. It is caused by Streptococcus equi subspecies equi and can spread quickly wherever horses mix.

The most useful rule is simple: if your horse develops a fever, nasal discharge or swollen glands, isolate first and call your veterinarian.

What is strangles?

Strangles affects horses, ponies and donkeys. The bacteria infect the upper airway and lymph nodes around the head and neck. These lymph nodes can swell and form abscesses. Severe swelling can make breathing or swallowing difficult, which is how the disease got its name.

Strangles is endemic in New Zealand, meaning it is already established here. Most uncomplicated cases recover with good care, commonly within four to six weeks.

How does strangles spread?

Strangles spreads through contact with infected nasal discharge or material draining from an abscess. Fever is often the first sign, before obvious nasal discharge or swollen glands, so a horse may become a risk before people realise it has strangles.

The bacteria can be transferred by:

• Nose-to-nose contact
• Shared troughs, buckets, feed bins and hoses
• Shared tack, halters, lead ropes, rugs and grooming tools
• Floats, trucks, stables, rails and yards
• Contaminated hands, clothing and footwear

NZEHA (NZ Equine Health Association)  advises that the bacteria may survive for four to six weeks in water troughs and for more than a month in dried discharge. Cleaning, suitable disinfection and thorough drying all matter.

Signs of strangles in horses

A raised temperature is often the first warning. A resting adult horse is generally around 37.2°C to 38.3°C, although normal readings vary slightly between horses. Exercise, travel, stress and hot weather can also raise temperature. Learn your horse's normal resting temperature so you can recognise a meaningful change.

Watch for:

• Fever
• Low energy or reduced appetite
• Thick white or yellow nasal discharge
• Coughing
• Painful swelling under the jaw or around the throat
• Abscesses that rupture and drain
• Difficulty swallowing, noisy breathing or respiratory distress

What should you do if you suspect strangles?

1. Stop movement. Do not transport the horse and do not bring new horses onto the property.
2. Isolate immediately. Prevent nose contact and use separate water, feed and equipment.
3. Call your veterinarian. Other conditions can look similar, so veterinary testing is needed.
4. Record temperatures. Check all horses twice daily if your veterinarian recommends it.
5. Create three groups. Keep sick, exposed and apparently unaffected horses separate.
6. Use strict hygiene. Care for healthy horses first, exposed horses next and sick horses last. Change or clean hands, clothing and footwear between groups.
7. Communicate early. Tell relevant property managers, event organisers and recent contacts while following your veterinarian's advice.

Healthy horses are handled first because working with a sick horse can contaminate your hands, boots, clothing and equipment. Handling sick horses last reduces the chance of carrying bacteria back to the healthy group.

How is strangles treated?

Most uncomplicated cases are managed with rest, careful nursing and veterinary monitoring. A horse may need pain relief, soft feed, help maintaining fluid intake or veterinary management of mature abscesses.

Antibiotics are not suitable for every case and should only be used when prescribed by the attending veterinarian. Do not open, squeeze or treat an abscess yourself unless your veterinarian has given clear instructions.

Can a recovered horse still spread strangles?

Yes. A horse may look well while still carrying the bacteria in its guttural pouches. NZEHA advises that about one in 10 recovered horses becomes a silent carrier.

Do not return a recovering horse to shared facilities or mix it with other horses until your veterinarian has advised on testing and confirmed the clearance plan.

Rare but serious complications

Most horses recover without complications, but owners should know about two uncommon problems:

• Metastatic strangles: abscesses develop elsewhere in the body rather than remaining around the head and neck.
• Purpura haemorrhagica: an immune reaction that damages small blood vessels. Warning signs include sudden swelling of the legs, head or underside of the abdomen, hives and red or purple spots on the gums or inside the eyelids.

Both require urgent veterinary assessment. Breathing difficulty is an emergency.

How to reduce your horse's risk

Quarantine new and returning horses

Keep new arrivals and horses returning from travel separate for 14 to 21 days. Check and record their temperature twice daily before mixing them with resident horses.

Travel sensibly

Do not travel a horse showing any sign of illness. ESNZ advises grouping only horses that travelled together and leaving at least two empty pens or stables between separate groups where possible. Avoid communal water and contact with unfamiliar horses.

Do not share equipment

Assign each horse its own buckets, feed bin, halter, lead rope and grooming kit. Clearly label equipment used for isolated or exposed horses.

Clean before disinfecting

Remove bedding, manure, dirt and nasal discharge first. Organic material can reduce the effectiveness of a disinfectant. Apply a product suitable for the surface, following its label for dilution and contact time, then allow the area or equipment to dry completely.

Discuss vaccination with your veterinarian

Vaccination may be appropriate for some horses, particularly frequent travellers, but it is not completely protective and timing matters. Current NZTR and Equine Veterinarians New Zealand advice is that vaccination during this outbreak is generally not recommended, except in rare circumstances after consultation with a veterinarian. Vaccinating a horse that is already exposed or incubating strangles may increase the risk of complications.

NZ Tack strangles preparedness shopping list

No product or supplement can guarantee protection from strangles. Isolation, early veterinary advice and consistent biosecurity remain the most important measures. These products can support monitoring, dedicated equipment, cleaning and normal nutritional health.

Monitoring and isolation essentials

• Safehorse of Sweden Horse Thermometer: useful for checking and recording temperatures.
• Vetpro Equine First Aid Kit: includes gloves, saline, dressings and general first aid supplies. It is not a strangles treatment kit.
• Dedicated feed and water containers: assign clearly labelled containers to each horse or management group.
• Ezy Ride Solid Nose Rope Halter with Lead: a washable set that can be assigned to one horse.
• Separate grooming equipment: keep brushes and tools with one horse or group.

Cleaning and routine horse care

• Eco Horse Tow and Glow Float and Truck Cleaner: helps remove dirt and organic material from transport. It is a cleaner, not a confirmed strangles disinfectant.
• Vetpro AntiBac Wash: a chlorhexidine cleansing wash with label directions that include general washing and hand washing. Use only as directed.
• AniDINE PVP Iodine Wash: an antiseptic skin and coat wash for routine care. Do not apply it to an abscess unless instructed by your veterinarian.

Supplements for normal health and immune function

Good nutrition supports normal immune function, but supplements do not make a horse immune to strangles and cannot prevent, treat or cure the infection.

• BetaVet Echinacea Premier: formulated to support normal immune-system function and natural resilience.
• NPC Health Equine Vitamin C: provides stabilised vitamin C with antioxidant properties and is marketed for support during stress, illness or recovery. Horses normally produce their own vitamin C.
• NPC Health Equine Vitamin E: supports normal antioxidant, immune, muscle and nerve function. It may be relevant when access to fresh green pasture is limited.
• Poseidon Daily Balance: a vitamin and mineral supplement with amino acids and digestive enzymes for diets that need nutritional balancing.
• AHD Equilibrium Mineral Mix: provides vitamins, minerals, salts and electrolytes to complement an existing feeding programme.

Choose supplements to correct a genuine dietary need, not simply because several products sound helpful. Do not combine multiple vitamin and mineral products without checking for duplicated ingredients. Selenium and some other nutrients can be harmful when over-supplied. Ask your veterinarian or an independent equine nutritionist to review the complete diet.

The four actions to remember

1. Recognise fever and other early signs.
2. Isolate the horse immediately.
3. Call your veterinarian.
4. Stop movement and use strict biosecurity.

Strangles is upsetting, but it should not carry a stigma. Early reporting and open communication help protect horses, owners and the wider equestrian community.

This article provides general information and is not a substitute for veterinary diagnosis or advice. Outbreak information and industry requirements can change. Check the latest official guidance before travelling or attending an event.

Sources and current guidance

• New Zealand Thoroughbred Racing: Strangles Information Hub
• New Zealand Equine Health Association: Strangles
• Equestrian Sports New Zealand: Current Event Biosecurity Advice
• New Zealand Veterinary Association: A Guide for Horse Owners
• Racing Integrity Board: Strangles Industry Advice
• American Association of Equine Practitioners: Strangles Guidelines