Vaccination is a process by which we stimulate the immune system to produce a defence mechanism against selected diseases. In Australia, we can vaccinate our horses against Tetanus, Strangles, EHV, Salmonella, Rotovirus, and Hendra. Most of these vaccines are given depending on a risk assessment of the horse and may apply to breeding horses specifically. The most common vaccines for horses is Tetanus and Strangles which is in a combined single injection and is called Equivac 2in1.
This is an important disease as horses are very susceptible, and if untreated, death can be very painful. It is very difficult and expensive to treat and therefore prevention is essential. Vaccines are very effective against the disease, and the only animals that this practice have ever had to treat were unvaccinated.
Tetanus is caused by a toxin that is produced by bacteria that contaminate wounds, often these can be pin pricks and can easily be missed by owners. Due to diligent vaccination this disease is becoming less of a problem in the equine world. However, if you have a horse with an injury, and you are unsure of the vaccination status a veterinary should be contacted to administer a Tetanus shot to ensure immediate cover.
This is a much less significant disease as it rarely causes death and can be readily treated with antibiotics. However, it is highly infectious and mainly effects young animals.
Vaccination for Strangles is essential in high risk areas where outbreaks have been recorded and in young horses as they are particularly susceptible. Unlike the Tetanus vaccine, Strangles vaccinations do not offer 100% coverage to the horse but will significantly reduce the symptoms if it does contract it, and slow the transmitting to other horses.
Special Consideration for foaling mares:
It is recommended that pregnant mares be vaccinated 4-6 weeks prior to foaling. This allows the mare to produce antibodies that can be passed into the colostrum, hence passing on to the newborn foal. This provides an immunity for the first few weeks of its life until its immune system is mature enough to respond to vaccines.
With October here, it is one month since foaling season began in Australia so today is the perfect day to discuss pregnancy and foaling in mares. We discuss what to expect during pregnancy and foaling, and the foal’s health after birth.
Duration of Pregnancy
The duration of pregnancy in horses is usually between 335 and 342 days but this can be quite variable ranging between 305 to 400 days. One of the most common concerns for clients is that their mares are going over their due date - so remember mares can go up to 400 days and still be ok.
One month before a mare is due, it is important to ensure that the mare is wormed and vaccinated for at least Tetanus/Strangles to give the foal the best immunity during its first three months of life. These antibodies are passed through the colostrum on the first day the foal suckles.
Signs of impending birth
Before a mare foals, she will display some physical signs. These signs can be quite varied depending on the mare’s history or lack of, but the most consistent sign is the filling up of the udder and teats with milk/colostrum, commonly known as “bagging up”. This can start a couple of weeks before birth and usually 24-48 hours before the foaling dry, waxy colostrum appears on the teats commonly termed “waxing up”. Other signs include lengthening of the vulva and loosing of muscles towards the back of the rump.
The three stages of labour
There are three main stages of labour in horses.
Stage 1 – getting ready
The first stage can start up to 4-5 hours before active labour begins. The uterus starts to contract and position the foal in preparation for birth. The mare becomes uncomfortable and restless and may start to sweat. She will walk around with her tail raised, may urinate frequently, and seem restless, getting up and down constantly.
Eventually, the allantochorion ruptures (water breaks) and this marks the start of stage two of labour.
Stage 2 – active labour
In the second stage of labour, mares are forcefully straining, and the foal is usually born within 20 minutes of commencement. The mare may lie down and strain for a few minutes and then get up and change position or rest. If there is active forceful straining for more than 20-30 minutes with no progression, there may be a problem and veterinary assistance should be obtained. The foal must be positioned with its two front feet first followed by the nose. If this is not observed a vet needs to be contacted immediately to assess the situation.
Upon presentation of the two front hooves and nose, the foaling should be quick once the shoulders pass through the pelvic passage. The amniotic sac will break on its own accord when the foal is expelled, however, you may remove it from the foal’s head once born. Allow the umbilical cord to break on its own accord and let the mare rest until she is ready to get up.
It is important to allow the mare to deliver with minimum interference and in a quiet, relaxed environment. This is especially important for maiden mares that may be made anxious by too much human involvement.
Stage 3 – post birth
The placenta should be expelled within 3 hours. If it does not veterinary assistance will be needed as the mare may have a retained membrane, which can be quite harmful. You should examine the placenta by spreading it out to ensure it is intact. Note: remembering that there will be a hole from the opening of the sack to allow the foal out.
After birth, the foal should stand within one hour and start sucking the mare within 2 hours, any longer than 2 hours to stand or longer than 3-4 hours to suck will require you to contact your vet immediately. The first milk or colostrum is absorbed during the first 24 hours of life, so for the best immunity, the foal should be sucking effectively within this time.
The foal’s first bowel movement or meconium is passed normally within 12 hours and ensures the bowels are working efficiently. Often colts will retain their meconium due to the narrowing of their pelvis compared to that of the females, this may cause colic. If the foal shows signs of non-productive straining or colic, there may be retained meconium and a veterinarian should be called.
After 24 hours it is important that the foal has an IgG blood test to ensure it has received enough antibodies from the mare’s colostrum. If it is low, then a plasma transfusion may be recommended.
It is important to remember that most of the time a mare will foal with no assistance and instinct takes over. However, owners can play an important role by observing the process to ensure everything is on the right track, and problems are dealt with promptly by contacting your veterinarian.