Understanding the signs, protecting your horses, and supporting their health through times of stress
For many horse owners, the word strangles is enough to make your stomach drop.
It is one of those diseases that reminds us how connected the equestrian community really is. Horses travel, yards share facilities, riders attend events, and unfortunately, illness can move quickly when we least expect it.
With recent strangles cases reported in New Zealand, many owners are asking the same questions:
What should I be looking for? How do I protect my horses? And is there anything I can do to support their health during times of stress?
The good news is that knowledge is one of the best tools we have.
Understanding the early signs, having good biosecurity habits, and knowing when to seek veterinary advice can make a significant difference.
And the most valuable tool you can have right now?
A thermometer.
What Is Strangles?
Strangles is a bacterial infection caused by Streptococcus equi subspecies equi.
It primarily affects the upper respiratory tract and the lymph nodes around the head and throat. The name comes from the characteristic swelling of these lymph nodes, which in severe cases can put pressure on the airway.
Despite the alarming name, strangles is rarely fatal, and most horses recover well with appropriate care and supportive management.
Strangles is considered endemic in New Zealand, meaning it continues to circulate within the horse population. This is why ongoing awareness, responsible horse movement and good biosecurity practices remain so important.
The bacteria spreads easily through direct horse-to-horse contact, but also through the things that move between horses.
This includes:
- Shared water buckets and feed bins
- Grooming equipment
- Tack
- Float surfaces
- Clothing and footwear
- Hands
- Other animals that have had contact with infected horses
- This is why biosecurity matters so much, especially when horses are moving between properties, competitions, clinics or training facilities.
Fever Comes First - Your Window of Opportunity
When many owners picture strangles, they think of swollen glands and thick nasal discharge.
However, these are often later signs.
One of the earliest signs of infection is usually a raised temperature, sometimes before a horse appears obviously unwell.
That short window is incredibly valuable.
A horse with a fever can be identified early, isolated and monitored — reducing the risk of spreading infection throughout a yard.
This is why regular temperature checks are one of the simplest and most effective habits horse owners can develop.
Signs to watch for include:
- Fever
- Reduced appetite
- Lethargy or looking “off”
- Thick nasal discharge
- Coughing
- Swollen or painful lymph nodes around the throat and jaw
- Difficulty swallowing or breathing in more severe cases
Young horses and those experiencing additional stress may require closer monitoring and more support during illness and recovery.
The Hidden Challenge: Carrier Horses
One of the reasons strangles can be difficult to manage is that some horses continue carrying the bacteria even after they appear completely recovered.
Around 10% of horses that recover may become carriers, often harbouring the bacteria within structures called the guttural pouches.
These horses can look completely healthy while still being capable of shedding bacteria and contributing to future outbreaks.
This means a horse that “looks better” is not always the same as a horse that is fully clear.
Working with your veterinarian on appropriate testing before returning a recovered horse to normal routines is an important part of protecting other horses.
What To Do If You Suspect Strangles
If you notice signs that concern you:
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Isolate the horse immediately - create distance from other horses while you seek veterinary advice.
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Contact your veterinarian - early veterinary guidance can help determine the appropriate next steps.
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Avoid moving horses - avoid non-essential travel, do not attend events or introduce new horses until you have veterinary advice.
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Review your hygiene practices - clean equipment, wash hands and avoid sharing items between horses.
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Early action protects not only your own horses, but the wider horse community.
What About Vaccination?
Vaccination can form part of a broader equine health plan and is something worth discussing with your veterinarian.
However, vaccination decisions should always consider your individual horse, management situation, risk factors and timing.
If you are considering vaccination due to current concerns, speak with your veterinarian about what is most appropriate for your horses.
Biosecurity: The Real First Line Of Defence
There is no shortcut when it comes to preventing the spread of infectious disease.
Good management practices remain the foundation.
Simple habits make a significant difference:
✓ Take temperatures regularly, especially during periods of increased risk
✓ Isolate new arrivals before introducing them to the herd
✓ Avoid sharing buckets, tack and grooming equipment
✓ Clean floats and equipment between horses
✓ Wash hands and consider clothing changes when moving between groups of horses
✓ Be mindful when attending events, clinics and busy facilities
For horses that compete, travel or attend shared facilities, it is also important to stay up to date with current requirements.
Always follow your governing body’s current requirements around health declarations, monitoring and testing before travelling or competing.
Requirements may change depending on the disease situation, event, discipline or location, so checking before you travel is one of the simplest ways to protect your own horse and the wider equestrian community.
These small actions are some of the most powerful tools horse owners have.
Nutrition And Supporting Normal Immune Function
Nutrition does not prevent infectious disease, but it plays an important role in maintaining the systems that allow horses to function normally.
The immune system is complex and relies on a wide range of nutrients to support normal cell function, antioxidant protection, tissue repair and energy production.
During periods of stress, illness, travel, competition or reduced feed intake, maintaining good nutritional support becomes especially important.
A horse that is unwell or recovering may eat less than normal, making it harder to meet their nutritional needs at exactly the time their body may require additional support.
Some nutrients involved in normal immune function include:
Vitamin C
Vitamin C is an important antioxidant that helps protect cells from oxidative stress and supports normal immune function.
Unlike humans, horses can naturally produce their own vitamin C. However, demand may increase during periods of increased physical stress, illness, travel or heavy workloads.
Vitamin C also plays a role in collagen formation, which is important for maintaining healthy tissues.
Vitamin E
Vitamin E is one of the horse’s most important dietary antioxidants.
It supports:
- Normal immune cell function
- Protection of cells from oxidative stress
- Muscle health and recovery
- Normal inflammatory balance
Horses in regular work, travelling frequently, or relying heavily on stored forage may require particular attention to their vitamin E intake.
Zinc
Zinc is a trace mineral involved in many processes throughout the body, including normal immune function.
It supports:
- Healthy skin and mucous membrane barriers
- Normal immune cell activity
- Tissue repair
- Antioxidant defence systems
The respiratory tract relies on healthy mucous membranes as part of the body’s natural first line of defence.
Selenium
Selenium plays an important role as part of the body’s antioxidant defence system.
It contributes to:
- Normal immune responses
- Protection against oxidative stress
- Normal muscle function
Selenium requirements in horses are relatively small, and supplementation should always be considered alongside existing feed and forage levels, as excessive intake can be harmful.
B Vitamins
B vitamins are essential for energy metabolism and normal cellular processes.
They support:
- Energy production
- Appetite and feed utilisation
- Normal nervous system function
- The energy demands of rapidly dividing cells, including immune cells
During periods of stress or illness, maintaining adequate nutrient availability can become especially important.
Omega-3 Fatty Acids
Omega-3 fatty acids are involved in maintaining normal inflammatory pathways and supporting overall cellular health.
They contribute to:
- Healthy cell membranes
- Normal inflammatory balance
- General wellbeing
Protein And Amino Acids
Protein is often overlooked when discussing immune health.
Amino acids are the building blocks needed for:
- Maintaining muscle
- Tissue repair
- Production of immune-related proteins
- Recovery following periods of stress or illness
For horses that go off feed during illness, maintaining adequate nutritional intake can become one of the biggest challenges.
The Bigger Picture
A healthy immune system is not supported by one single nutrient.
It relies on many systems working together.
Good quality nutrition, appropriate management, hydration, rest, stress reduction and veterinary care all play a role in supporting a horse’s overall resilience.
During times of increased risk, the goal is not to “boost” the immune system, but to provide the foundations that allow the horse’s body to function normally.
The Foundations Don’t Change
Outbreaks are a reminder that horse health starts long before clinical signs appear.
Knowing your horse’s normal temperature, behaviour and appetite gives you valuable information. Good biosecurity reduces risk. Good nutrition supports the body’s everyday needs.
And right now, one of the most valuable things in your tack room is probably something you already own.
A thermometer.
It takes less than two minutes.
It may not be exciting, but it could be the thing that helps you catch a problem early and protect the horses around you.
This article is intended for educational purposes only and does not replace veterinary advice. Strangles is an infectious disease requiring appropriate veterinary assessment and management. If you suspect your horse may have strangles or any other infectious disease, isolate the horse and contact your veterinarian.
Stay up to date with the current Strangles status in NZ here.
