from the Vet Corner Archives
Part of Horse Previews Magazine website. Posted on 04/06/2000; 2:00:00PM.
Veterinary Corner 04/00: Colostrum - An Essential Ingredient for a Thriving Foal
by Frosty Franklin, DVM
Edgecliff Equine Hospital
S. 1322 Park Road, Spokane, WA 99212 * 509/924-6069
Spring has sprung and with it comes the anticipation of the arrival of new foals. Many of you may be patiently waiting for the big day. In a perfect world, the mare foals without any difficulty. She hasn't leaked any colostrum and it is of the best quality. The foal is up and nursing within an hour or two and absorbs more than enough immunoglobulins from the colostrum. When the veterinarian performs one of the many tests available to check and make sure passive transfer has occurred, it confirms that all is well. Most of the time, this is indeed the case and the new foal owner never gives another thought to colostrum. However, in some cases the foal does not receive enough colostrum and a failure of passive transfer (FPT) has occurred. It is in these cases that the importance of colostrum is brought to the forefront.
Colostrum is the mare's first milk which contains important immunoglobulins capable of protecting the foal from infection during its first months of life. The foal doesn't begin producing these until it is born. Thus, passive transfer of immunoglobulins from mare to foal via colostrum ensures that the newborn will have a line defense until its immune system is up and running. Produced in the mare's udder during the last 2-4 weeks of gestation in response to hormonal changes, colostrum is only produced once during the pregnancy. It is replaced with normal milk within 12 hours from the time the foal first suckles. Good quality colostrum is typically sticky, thick, and yellow, though appearance can be misleading and shouldn't be the only factor used to determine whether passive transfer has occurred. The mare will produce approximately 300 ml of colostrum per hour, and generally produces 5 liters in the first 18 hours.
The most common reason a foal does not receive adequate amounts of colostrum is premature lactation. For reasons that are not clearly understood, some mares will leak colostrum prior to giving birth. By the time the foal is born, all the colostrum is gone. Other reasons for failure of passive transfer include inadequate immunoglobulin content in the colostrum, failure of the foal to nurse and ingest large enough amounts of colostrum, and inability of the foal to absorb the colostrum.
Other than premature lactation which is easily seen, it is very difficult to determine whether the foal has received the immunoglobulins it needs by any means other than a blood test. For this reason, it is imperative that a veterinarian examine your newborn foal 12-24 hours after it is born. Using one of many tests available, the veterinarian can determine whether the foal has adequate levels of immunoglobulins in their blood. It is important not to wait too long to have your foal checked because if a FPT has happened isolation and/or treatment must begin immediately. Guidelines have been established which help the veterinarian and owner determine the best course of treatment. Keep in mind these are only guidelines and other factors like environment, overall health of the foal, etc. also come into play when deciding whether treatment is necessary. An IgG level above 800mg/dl is considered normal and no treatment is necessary. Levels between 200-400mg/dl are considered a partial FPT and may or may not require aggressive treatment. Levels below 200mg/dl are considered complete FPT and require some sort of treatment.
Regardless of the manner in which FPT has occurred, the next step in treating the foal is the same. The foal needs to receive a replacement for the immunoglobulins it did not get from its mother. The two most common means of replacing lost colostrum are giving colostrum which has been kept at a colostrum bank, if available, or giving the foal equine plasma. Colostrum can be stored for at least a year when frozen at -4 F (-20 C). Frozen immunoglobulins are stable for much longer than that but the overall quality of the colostrum deteriorates over time. Giving the foal thawed colostrum is the best option as it has high concentrations of immunoglobulin in it. However, in most cases frozen colostrum is not available and an alternative source of immunoglobulin must be used. The alternative is equine plasma which is readily available through your veterinarian. Because the levels of immunoglobulin are not as high in plasma, it is not as effective as giving colostrum and is often a costly option.
As you can see, colostrum is an important ingredient for a healthy foal. In most cases, adequate passive transfer occurs and an alternative method for giving the foal immunoglobulins isn't necessary. Some foals, however, will need either colostrum or equine plasma to help them fight infection for the first few months of their lives. In order to ensure that at risk foal will receive the best substitute for their own mother's colostrum, another mare's colostrum, we must continue to support our local colostrum bank. You can do this by collecting 200-250ml of colostrum 2-6 hours after birth from your mare after your foal has suckled several times and preferably from the teat opposite that which your foal first nurses. You need not worry about your foal not getting enough colostrum because 200-250ml represents only about 10% of the total colostrum. For more information about the colostrum bank and how you can donate, please call or visit the Horse Previews website at
http://www.horse-previews.com/colostrombank or alternatively call Horse Previews at 1-800-326-2223.
Until next month, happy trails.