One of the first questions a veterinarian is likely to ask when a foal has become ill is: ‘Did you have the blood tested?’ In other words: was a ‘Snap Foal Test’ carried out to find out if the foal has ingested sufficient antibodies? As with all other mammals, the immune system of newborn foals has not yet fully developed. The production of antibodies takes longer than in mature horses, even when the pathogens are present in the direct environment. What’s more, and contrary to other mammals, foals do not get antibodies via the placenta. So foals are born without antibodies and the only way to obtain them is by drinking the mare’s beestings. When the foal has not ingested sufficient antibodies the chances are fairly high it will become ill or even contract a fatal infection.
Antibodies are the result of a complex system in the body, i.e. the immune system, where all sorts of cells and mechanisms work together to fight off pathogens and eliminate them from the body. Antibodies are only produced after the body has been exposed to the pathogen and each pathogen has its own specific antibodies. As soon as this pathogen re-enters the body the antibodies attach themselves to the pathogen and start breaking it down. So this is how antibodies contribute to the resistance of the animal. The immune system of any newborn mammal is still incomplete and starts to develop over the first few weeks and months of its life. To make sure they have sufficient resistance against pathogens in their direct environment, most unborn mammals receive antibodies from their mums via the placenta. Unfortunately, this is not the case with foals, which is why they are extra vulnerable and their dam’s milk is so crucially important.
During the last month of gestation the mare produces antibodies in her milk. These are antibodies specific to the pathogens in the surrounding area or that were produced after vaccinations. With this in mind it is not a good idea to move mares to another stable shortly before the time of birth. The time will be too short for them to produce antibodies against germs present in the new environment so that the foal will not be protected against these new germs.
The first milk, called beestings, is rich in antibodies and is only produced during the first hours before and after birth. It is therefore crucial for the foal to drink from the beestings and become more or less protected. After drinking, the antibodies from the beestings are absorbed by the small intestines and transported to the blood via the lymphatic vessels. But this is where the catch is: the small intestines only absorb the antibodies during the first 24 hours of the foal’s life. After that time the small intestines lock out larger proteins such as antibodies and absorption of antibodies can no longer take place via the intestines. So the sooner the beestings are ingested the better the absorption of antibodies will be.
It is important that the foal drinks enough shortly after birth to have sufficient antibodies against various germs.
Foals that have not absorbed adequate amounts of antibodies from the mare are very vulnerable to pathogens such as bacteria, viruses or parasites. Sadly, they will soon become ill. Common diseases are diarrhoea, inflammation of the umbilicus or joints, pneumonia or other infections. It’s not uncommon to see infections elsewhere in the body too, which can very quickly lead to weakness, fever, refusing to drink and even death.
From eighteen hours after its birth the foal’s blood can be tested for the amount of antibodies. This can be done with the so-called Snap Foal Test. Most of the time this test is carried out when there is some doubt about the amount of the foal’s intake of beestings. It would be more common sense however to use this test for every foal, because no one can tell what the quality of the beestings is. When the beestings contain few antibodies the foal will still be insufficiently protected even after an adequate intake of the milk.
If the foal has not ingested enough antibodies it is key these antibodies are administered manually. There are two ways to do this, depending on the foal's age.
When the foal is younger than eighteen hours and the foal has clearly hardly drunk from the milk, the mare can be milked so that the beestings can be administered to the foal with a stomach tube. At this stage the antibodies can still be transported to the blood through the wall of the small intestines. Once the foal is older than eighteen hours the intestinal wall will be incapable of absorbing enough antibodies and in this case the antibodies must be directly injected into the bloodstream via a sterile drip, using plasma from a healthy animal.
When the foal doesn’t drink at all or not enough it has obviously not ingested sufficient antibodies. Foals that cannot stand upright due to weakness, illness, deviating conformation or a slippery surface will not drink. Often, big foals also struggle to drink. Other reasons for not drinking could be distraction by their surroundings or a very difficult birth. When the foal struggles to stand or to find the udder it is an option to try and guide the newborn foal to the mare’s udder. When this doesn’t go smoothly and the foal gets exhausted the mare must be milked and the foal should be bottle-fed with the beestings. That gives it a chance to regain energy so that it can try suckling from the mare on its own.
It’s not always the foal who is responsible for insufficient antibodies, it could just as well be the mare. Some mares stream milk before foaling, wasting good-quality beestings. In case you have noticed this it is advisable to organise a different source of antibodies from elsewhere before the foal is born, for example beestings from another mare or plasma. Feeding these sources of antibodies to the newborn foal must be done several times. Alternatively, it is possible that the mare refuses to let the foal drink because of pain, weakness or inexperience. If this happens best practice is to hold the mare or tie her up so that the foal gets a chance to drink from the beestings. Maybe the beestings don’t contain sufficient antibodies. So even when the mare produces enough milk and the foal drinks well, the foal can still be inadequately protected. This is why it is sensible to ask the veterinarian to check the quality of the beestings.
To avoid a shortage of antibodies in foals it is important to make sure the mare is healthy and well-vaccinated and can give birth in a quiet, clean and if possible familiar place. Furthermore, good observation after the foal’s birth to check if it is drinking properly is vital. If you notice that the intake of beestings is not taking place for one reason or another, it is absolutely key to intervene as early as possible and if necessary call the veterinarian so that the beestings can be administered by way of a tube or a plasma infusion. No matter whether the foal drinks or not, the best advice is to carry out a Snap Foal Test when the foal is older than eighteen hours. That is the only way to be sure the foal has ingested sufficient antibodies and is adequately protected.
To avoid a sick foal, it is important that the mare foals in a quiet, clean and, if possible, familiar environment.