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as a result of blood groups: ICTERUS |
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| It has been known for many years that foals can die when the difference between the lood groups of mare and stallion is too great. For a long time, it was a familiar problem among English thoroughbreds and riding horses such as the ones registered by the KWPN. It was not until recently that this problem was cropping up and possibly increasing among Friesian horses. This article is more practical than theoretical in nature. After all, it is more important to try to avoid this misery or to recognize it in the early stages. How does it develop? In general, it is comparable to what happens among Rhesus monkeys and human babies. When the father is Rh positive and the mother is Rh negative, the baby can also be Rh positive and have problems even before birth. Although horses do not have an Rh factor, they do exhibit other blood group factors, e.g., Aa and Qa. The Qa has never been observed among Friesian horses, but the Aa has. Once fertilization has occurred, all the blood groups of the foal have been determined. When the stallion passes on his Aa blood group to the foal and the mother lacks this blood group, problems can occur. The unborn foal develops and grows inside the uterus which offers an effective barrier between mare and foal. There is no contact between the blood of mother and foal as long as no wounds occur. It can happen, however, that a foal can kick hard enough to cause a wound in the uterus so that blood cells from the foal have access to the mare's circulation system. In itself, such an exchange of blood cells is not so serious; the wound will usually close, and the owners will not notice anything has occurred. Inside the mare, however, something has indeed occurred. The blood cells from the foal contain the blood groups received from both sire and dam. The blood groups inherited from the dam produce no problems, but those from the sire sometimes do if they are not the same as those of the mare. When the mare has no Aa blood group, and the foal does, the mare's body reacts to these 'foreign bodies' by developing antibodies as a form of protection against the Aa blood group. This is a process similar to the body's reaction to an invasion of germs that enter through a wound. Since these antibodies cannot reach the unborn foal because of the barrier formed by the uterus, nothing happens to the foal during the mare's pregnancy. After the foaling takes place These antibodies, however, show up in the mare's colostrum. When the foal starts to nurse, these antibodies enter his circulatory system and cause a reaction in which the red blood cells degenerate. The more antibodies he absorbs, the more and the faster the degeneration of blood cells. If it goes too far, the foal can even die. What symptoms does the foal display? Usually, these are strong foals that quickly drink a lot of colostrum. It is not uncommon that the foal becomes weak within '12 to 18 hours and displays yellow in the white of the eye and mucous membranes. The foal will often die quickly. The yellow color develops due to the products of decomposition from the damaged blood cells. In other cases, when it is not so acute, the foal becomes weak after 2 to 4 days, can no longer stand and then dies. In these less acute cases, the yellow color is often less conspicuous. What to do Call your veterinary! In a number of cases, the foal can be saved with a blood transfusion. For the donor, it is best to use a horse that has never been pregnant (yearling or gelding). Afterward, keep the foal away from the mare for five days following the birth. During this time, the mare will have to be milked. Not every foal that dies, however, dies as a result of a conflict in blood groups. How can you be sure that the cause of death has been a result of conflicting blood groups? Certain steps have to be taken to make sure of the diagnosis.
An old wives' tale
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