The average gestation of a horse is 340 days. Unfortunately, sometimes mares deliver early. Any foal with a gestational age less than 320 days is considered premature and is at risk for many life-threatening conditions. Several common complications of prematurity include failure to produce surfactant in the lungs, which can lead to severe pneumonia, failure to ingest adequate colostrum (failure of passive transfer), which can lead to septicemia, and immaturity of the small carpal and tarsal bones, which can lead to arthritis and angular limb deformity or laxity of the joints of the legs.
Failure of Passive Transfer (lack of colostrum)
When foals are born, they have no antibodies against pathogens in the environment until they stand and nurse colostrum from the mare. Colostrum is the antibody rich milk the mare makes for the foal to drink right after birth. Special cells in the intestinal tract of the newborn foal allow them to absorb the antibodies into their bloodstream for the first 12 hours of life only. After that, the antibodies are digested along with the milk. A foal can have failure of passive transfer three ways; if the foal does not nurse enough within 12 hours after birth, if the mare fails to make colostrum, or if the mare leaks the colostrum out of the mammary gland before the foal is born. A test can be performed on the foal’s blood to assess whether he or she has adequate antibody protection. One commonly used test is the SNAP test, usually performed 18-24 hours after birth. Foals should have an antibody level (IgG) of greater than 800 mg/dl. If the foal did not get enough antibody in it’s mother’s milk, a plasma transfusion and treatment with antibiotics is recommended. If failure of passive transfer goes unrecognized, the foal is at much greater risk for neonatal septicemia and a host of other life threatening problems.
The umbilicus, or navel is the stalk that connects the unborn foal to the mother before birth. It contains the urachus, a connection to the foal’s bladder, the umbilical vein and 2 umbilical arteries.After the foal is born, the umbilical stalk is broken when the mare stands up and the structures of the umbilicus quickly start to seal up. Unfortunately, sometimes bacteria may get into one of the structures before it seals and cause an umbilical abscess. Signs of an umbilical abscess include drainage from the umbilicus and swelling of the stump or the surrounding body wall. Often, the foal will have a fever as well. Treating the umbilical stump with a disinfectant can help prevent this problem, but it can occur in any foal. In most cases, umbilical abscesses must be removed surgically. Left untreated, these abscesses can invade the foal’s liver, break into the foal’s abdomen or bladder, or bacteria can get into the bloodstream and cause septicemia and infected joints.
How can these neonatal foal problems be prevented?
- Make sure the mare is vaccinated 2-6 weeks prior to foaling
- Make sure the breeding records are accurate so you know when to expect the foal. Always try to attend the foaling and make sure the foal is up and nursing within 3 hours of birth. If not, Call your veterinarian right away!
- Always have your veterinarian visit and examine your foal within the first 24 hours of life. He or she will examine your mare and foal and decide if any tests or treatments are necessary. Unfortunately, the problems described here are only a few of the problems that can affect the newborn foal. Early detection and prevention of the problems make for happy, healthy foals!