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.

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.

Unfortunately strangles is a difficult disease to effectively vaccinate against. The first years’ course requires three shots 2 weeks apart followed by annual booster shots. These shots can be combined with tetanus vaccination to reduce the number of vet visits and injections. Vaccination may not prevent your horse getting strangles but it will be much less severely affected and will recover much more quickly.

Strangles is caused by the bacterium Streptococcus equi equi. It is highly contagious and can be passed from horse to horse via direct contact or on equipment or surfaces such as bridles and shared water troughs. The horse will get a high temperature followed by a snotty nose and swollen glands at the throat that often abscess and rupture. Occasionally internal lymph nodes can be affected which can be fatal. Most horses will eventually completely recover but will be out of action for many weeks. Some horses perpetually carry the organism in their guttural pouches; this is one way the disease persists.

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:

Innovator EHV-1/4 helps protect against respiratory disease caused by either of the 1 or 4 strains of herpes virus. The first injection should be given from 5 months of age and needs to be boosted 3 to 4 weeks later. To maintain protection a booster should be given every 6 months. This is recommended where there are a lot of young horses kept together such as studs and racing stables or if you want to reduce the chances your competition horse will develop a cold during the season.

Pneumabort-K+1B helps protect in-foal mares against the risk of herpes virus abortion or the birth of a sick foal. It should be given in the 5^th, 7^th and 9^th months of pregnancy. This vaccine is recommended for any mares going away to stud to foal as the risks are much greater. However any in-foal mare can abort due to herpes virus so it is also recommended for any valuable pregnancy.

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 8^th, 9^th and 10^th month of gestation. It will protect the foal via antibodies in the colostrum and while suckling the milk from the mare.

Equity Oestrus Control Vaccine. 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