Dr. Michele Roseburg, McKinlay & Peters Equine Hospital
Spring has finally reached Spokane! Running between melting drifts of snow are the first few foals of 2019. Ideally the veterinary-patient relationship with each new foal should begin in the first 12-24 hours of life. This is an ideal time to evaluate the foal for general well-being, identify and address limb deformities, and check the foal’s blood for level of transfer of antibodies from the mare.
Foals are born without any antibody protection against pathogens in their environment. They depend on protection received through drinking colostrum (the first milk) from their dam. The foal’s gut has the ability to absorb antibodies carried in the colostrum for the first 12-24 hours of life. After 24 hours, the lining of the gut changes and is no longer able to absorb these antibodies, which is why timing is so crucial. If the foal is tested prior to 24 hours of age, additional colostrum can be administered orally (if available) to try and increase the foal’s antibody levels. If the foal is already 24 hours old when tested, the gut has closed and supplementation must be done through intravenous administration of plasma specially formulated for the task.
To check transfer of antibodies from dam to foal, a stall-side test can be run on the foal’s blood. The test specifically looks for levels of Immunoglobulin G (aka IgG). Failure of passive transfer is how we describe an insufficient level of antibodies in the foal. This does not guarantee that the foal will become sick, it just puts them at a higher risk of being susceptible to infection from bacteria and viruses in their environment. Failure of passive transfer can occur for a few different reasons, including poor quality colostrum from the dam, excessive leakage of milk prior to giving birth, or the foal not nursing properly.
To ensure that a mare’s colostrum has the most beneficial antibodies it is important to vaccinate your mare according to veterinary recommendations. Mares should receive vaccine boosters 4-6 weeks prior to their due date to ensure that the foal will receive antibodies associated with those vaccines through the colostrum. This is extremely important so that the foal is immediately protected against preventable diseases such as tetanus since foals cannot be vaccinated themselves until three or four months of age.
As the saying goes, an ounce of prevention is worth a pound of cure. All of us at MPEH are looking forward to meeting your new foals.