Strangles has been in the news since it turned up on a dozen North Island horse properties, forcing new health rules on racing and putting owners on alert. We have covered the outbreak and the racing response separately. But for a lot of horse owners the first question is simpler. What is strangles, and how worried should they be? Here is a plain guide to the disease behind the headlines.
What strangles is
Strangles is a bacterial infection caused by Streptococcus equi subspecies equi. It attacks the upper airways and the lymph nodes of the head and neck, and horses have suffered from it for centuries. The name comes from the worst old cases, where badly swollen lymph nodes pressed on the airway and left the horse struggling to breathe.
Despite the name, strangles is rarely fatal. Most horses run a fever, feel miserable for a week or two, and recover fully within four to six weeks. The problem is not how dangerous the disease is but how easily it spreads, which is what makes it such a challenge for industries built on horses travelling and mixing.
The symptoms to watch for
The first sign is usually a fever, often above 38.5°C, before anything else shows. After that comes tiredness, loss of appetite, a thick yellow discharge from the nose, a cough, and swelling of the lymph nodes under the jaw. Those nodes often abscess and burst, draining thick pus. Once they drain, most horses start to get better.
How it spreads
Strangles spreads easily by both direct and indirect contact. The bacteria live in the nose and throat secretions of infected horses.
Direct spread happens through ordinary horse contact, nose to nose over a fence, shared grazing and mutual grooming. Indirect spread is the harder one to control. The bacteria are carried on shared gear such as water buckets, feed bins, grooming kits, tack, halters and twitches. They travel on the hands, clothing and footwear of people moving between horses, on vehicles, and even on farm dogs and other animals that have been near an infected horse.
The bacteria also survive in the environment. They can last four to six weeks in a water trough and more than a month in dried discharge on stable walls or fittings, though sunlight and thorough cleaning and disinfection kill them. That is why an empty paddock or a borrowed float can still pass the disease on days or weeks later.
Silent carriers
The hardest part of strangles is the silent carrier. About one in ten horses that recover keep carrying the bacteria, usually in the guttural pouches, which are air-filled cavities at the back of the head. These horses look completely healthy but can still shed the bacteria and start a fresh outbreak. It is how strangles stays in the horse population and reappears months or even years later.
What owners can do
Vets agree the most useful tool is a thermometer. “Ultimately, a thermometer is your best friend right now,” said Dr Holly Blue, head of veterinary services at the New Zealand Veterinary Association. “If you notice a fever especially after movement, travel or contact with unfamiliar horses, treat it as strangles until proven otherwise.” Because a fever shows up before a horse looks infectious, daily temperature checks can catch a case a day or two early, and that can be the difference between one sick horse and a whole yard shut down.
After monitoring, the basics are isolation and hygiene. Separate any suspect horse straight away, keep dedicated buckets, gear and ideally handlers for sick and healthy groups, disinfect floats and equipment between horses, and do not move animals until a vet gives the all-clear. Treatment is mostly good nursing, rest, soft feed, warmth and clean water, and most horses recover without antibiotics. Vets usually avoid antibiotics in simple cases because they can interfere with the natural draining of the abscesses. A vaccine is available in New Zealand and can reduce how bad an outbreak is, but it does not replace good biosecurity.
Getting the diagnosis right matters too. Lab testing should confirm Streptococcus equi subspecies equi, because a common relative, subspecies zooepidemicus, does not cause strangles and can confuse the picture. Testing may involve nasal swabs, PCR tests, blood tests, and, for tracking down carriers, an endoscope to sample the guttural pouches.
Not just a racing problem
Strangles can affect any horse in any discipline. Racing reacted fastest because racehorses travel and mix constantly, but sport horses, eventers and pleasure horses live much the same travelling life and face the same risk. Harness Racing New Zealand and Equestrian Sports New Zealand have both told members to watch for fever after travel and to keep new horses separate for 10 to 14 days. Because horses move between regions and disciplines, one population can carry the infection to another, which is why the whole industry is watching the Waikato outbreak, not just racing.
Where the outbreak stands
For now the Waikato outbreak looks contained, and the industry’s quick response has been widely praised. But strangles is endemic in New Zealand, and its habit of hiding in healthy-looking carriers means it is never far away. The best defence is a simple one, owners in every discipline taking their horses’ temperatures and being willing to stay home when the number climbs.
Have you dealt with strangles in your yard, or have a question about protecting your horses? Share your experience in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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