Bay Vets
Bay of Islands Veterinary Services has been providing top quality veterinary care to the animals of the beautiful Bay of Islands for over 50 years.
Strangles is a highly infectious disease passed between horses. Young horses in large groups and horses that come in contact with lots of others are most at risk. Risky activities include competitions, horse treks and going to stud. Strangles is still a common disease and outbreaks frequently occur on large studs amongst the young horses. If you are taking your horse to a stud or it is regularly in contact with lots of other horses it is advisable to vaccinate against strangles.
UPDATE 7 July 2026- Outbreaks of Strangles across multiple racing stables in the Waikato have been reported. Although it currently appears to be contained, spread beyond racing stables and the Waikato is likely to occur.
Strangles is a highly contagious bacterial infection of horses that causes severe illness, although death is rare. Affected horses can have a range of symptoms, but most commonly lethargy, fever, nasal discharge, and noticeable swelling of the lymph nodes around the throat. More severe cases can result in trouble breathing, swallowing, and abscessing of the lymph nodes. Horses at high risk of contracting strangles are those that travel and have exposure to lots of other horses. Strangles is passed through mucus from the nose and mouth, so contamination of equipment is possible, and direct horse-to-horse contact is not always required.
Monitoring the temperature of horses that travel regularly can help to recognise early disease. Vaccination is available to help prevent disease. There is currently a limited supply of strangles only vaccinations across New Zealand, but we do have 2in1 vaccine (strangles and tetanus) available. Horses require 3 vaccines two weeks apart before they have full protection.
If you suspect your horse may have strangles, isolate from other horses immediately and call our Waipapa clinic (401 6654)
Tetanus is an uncommon but invariably fatal disease in horses. Any horse can develop tetanus at any time from a wound so small you may not even be aware it exists. Every horse should be vaccinated against tetanus from three months of age. The vaccintaion programme requires two shots a month apart in the first year, then a booster shot a year later. After the first two years boosters are only required every five years. The vaccination can be combined with the strangles shots to reduce vet visits and the number of injections. Pregnant mares should be boosted two to four weeks before foaling to protect the mare during foaling and the foal in its’ first few months.
Tetanus is caused by the toxin from the bacteria Clostridium tetani. It causes the animals muscles to contract until it is unable to breath, an extremely unpleasant death. Horses become infected after the tetanus spores, that are everywhere in the environment, enter a skin wound. Small puncture wounds are often the worst as they create an anaerobic (without oxygen) environment favoured by the bacteria. This is why we commonly give an anti-toxin shot to any horse we see with a wound or foot abscess. The anti-toxin is not a vaccination; it is just short term protection against infection for any horse with an unknown vaccination history. But remember, your horse could pick up a tetanus infection from such a small wound that you may be unaware of it.
Equine Herpes Virus has a number of different strains that can cause a number of diseases. The most common is a viral cold which presents as a dull horse with a snotty nose. Infection can cause abortion in mares or the birth of sick foals that will die regardless of treatment. Less commonly, infection can cause neurological disease, horses develop paralysis from which they may never recover.
There are two different vaccines available depending on what the aim of vaccination is:
The neurologic form of herpes virus infection is rarely seen in New Zealand and there are currently no vaccines available that claim to protect against this form of the disease.
Herpes viruses are common in the horse population and once infected many horses will carry the virus for life hidden within certain cells of the body. At most times the horse will be totally unaffected by it but on occasion the virus can come out of hiding and cause disease, usually due to some stressor. Therefore, a horse in complete isolation can suffer from herpes virus disease or abortion. However, being in contact with other horses with clinical disease is the biggest risk factor for developing disease. If a mare aborts it is always a good idea to move any other in foal mares well away from any contaminated tissues, areas and equipment.
If your horse does develop a snotty nose, it is important to give it complete rest until resolved. Viral infections lower the body’s defences and can lead onto more serious bacterial infections such as those that cause pneumonia.
Salmonella is a serious infectious bacterial disease causing gastroenteritis in mares and young foals. Affected horses, particularly foals, will die without medication and intensive nursing care. Disease from Salmonella infection is rare in horses but outbreaks have occurred on large horse studs. If you have a mare going away to stud it is advisable to ask the stud if they recommend Salmonella vaccination, if they suspect they may have a problem they will recommend you vaccinate your mare. Humans can get sick from Salmonella carried by animals.
The vaccine is given to the pregnant mare 8 and 4 weeks prior to foaling. This will protect the mare directly and the foal via antibodies in the colostrum. The foal may be vaccinated directly from 4 months of age with a booster 4 weeks later. If the mare was not vaccinated the foal can be vaccinated from 1 week old but will require boosters 4 weeks and again 6 months later. After the first year just a single annual vaccination is required.
Rotovirus is a viral cause of gastroenteritis in foals. Rotovirus is generally only a problem on studs with a large number of foals; once there has been an outbreak it is likely the stud may have a problem every year. If you have a mare going away to stud it is advisable to ask if they recommend Rotovirus vaccination, if they know they may have a problem they will recommend you vaccinate your mare.
The vaccine is just given to pregnant mares in the 8th, 9th and 10th month of gestation. It will protect the foal via antibodies in the colostrum and while suckling the milk from the mare.
While oestrus (coming in season) is not a disease, there is a vaccine against it. It is designed to prevent oestrus related behavioural problems experienced by some mares such as squealing, nervousness, erratic performance etc.
The initial course requires two injections 4 weeks apart. Control of oestrus develops 10 to 14 days after the second dose and can be expected to last at least 3 months but may continue for 6 months or even longer. Booster doses can be given as needed but little information is available regarding the required frequency or duration of action as each horse will respond differently.
This vaccine should never be given to any mare or filly ever intended to be used for breeding.
Hilary Shaw, BVSc, BAgSc, Bay of Islands Veterinary Services
Bay of Islands Veterinary Services has been providing top quality veterinary care to the animals of the beautiful Bay of Islands for over 50 years.
