Foals and Colostrum
By Brandi Holohan, DVM, Pilchuck Veterinary Hospital
A new foal is a wondrous thing when the delivery goes well, the mare-foal pair bond, and nursing successfully happens soon after foaling. But when is it a concern that the foal is not nursing appropriately? What are the time constraints? What are the things to be watchful for? What tests should be run to confirm the foal has ingested enough life-giving immunoglobulins/ antibodies to keep the foal healthy until its immune system kicks in?
The acquiring of immunity via the first milk, colostrum, is referred to as passive transfer. The antibodies are absorbed directly through the GI system of the foal within the first 24 hours of life. It is best for the foal to be up and nursing well in the first 2 hours after birth to maximize the amount absorbed. The ability of the foal to absorb these large proteins rapidly declines 6 hours after foaling. Most of the absorption takes place in the first 8 to 10 hours. (This ability of the GI tract to absorb these special proteins also allows it to absorb ingested bacteria, so it is advisable to have your foaling area be relatively clean and dry. Foals, like small children, put their mouths on everything while they are learning to nurse.)
The mare typically starts to produce colostrum in the days preceding foaling. This special secretion from the mammary gland is thick, sticky and sweet and has an amber hue. If the mare starts to drip or stream milk for a period of time prior to or after foaling, she may lose all her colostrum to the ground. If you notice your mare is dripping/streaming milk for longer than a few hours, it would be a concern that her supply may be depleted. If the foal is not catching on to the nursing skill, you can catch the dripping milk in a clean container to administer to the foal later. A mare can also make poor-quality colostrum (inadequate amount of needed antibodies).
If there is concern about the foal’s intake of colostrum, several things can be done shortly after birth. If the foal is not catching on to the skill of nursing and the mare hasn’t lost too much milk, the mare can be milked and your veterinarian can administer the colostrum to the foal by passing a tube up the nostril, down the esophagus and into the stomach. This can also be done with colostrum that was saved and frozen from another mare. It should be thawed in a warm water bath. Do NOT microwave or overheat because the proteins can be damaged by excessive heat. This should be done within the first 6 to 8 hours after birth. Hyperimmune plasma can also be tubed to the foal.
A blood sample can be taken 18 to 24 hours after birth to determine if the foal has received an adequate amount of antibodies. This is a measurement called an IgG test. Results are often available within 4 to 24 hours, depending on the laboratory your veterinarian uses. This can also be done stall-side but is less accurate. If inadequate, the foal would need to be given hyperimmune plasma via a blood transfusion, as the foal can no longer absorb oral colostrum. If the number is less than 400 mg/dl, it is considered failure of passive transfer (FPT), and the foal will likely need one to two units of plasma. If the numbers are 400 to 800 mg/dl, it is partial failure of passive transfer, and the treatment would often be giving a plasma transfusion or prophylactic antibiotics depending on the actual numbers and other risk factors. Foals that have been diagnosed as FPT are at increased risk of fatal infections and subsequent early death. Because of the consequences of poor colostrum intake, it is advisable that all foals have their IgG levels tested as part of the new foal/post-partum mare exam.
Pilchuck Veterinary Hospital offers equine ambulatory care, referral hospital services and 24/7 emergency. Call 360.568.3111 to schedule a consultation with one of our equine practitioners.
Article added 2.10.15