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| − | | + | [[Neonatal Isoerytholysis]] |
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| − | =Alloimmune haemolytic anaemia of the newborn=
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| − | An alloantigen is an antigen existing in alternative (allelic) forms in a species, thus inducing an immune response when one for is transferred to members of the same species who lack it. So alloimmune haemolytic anaemia occurs when a neonate inherits the sire's blood type and drinks colostrum from the dam, which contains antibodies against the sire and thus the neonate's red blood cells.
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| − | It can naturally occur in humans (Rhesus disease) and foals (neonatal isoerytholysis) and can be induced in pigs and cattle by vaccines containing allotypic red blood cell antigens.
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| − | ==Neonatal Isoerytholysis (NI)==
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| − | Occurs in some foals, and always occurs in mules due to the incompatibility of the sire and dams blood types.
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| − | '''First pregnancy from a stallion with incompatible blood type to the mare:'''
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| − | * Mare is mated with a stallion with an incompatible blood type.
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| − | * The neonate may inherit the sire's blood type.
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| − | * At parturition, or because of placentitis, RBCs from the foal enter the maternal circulation.
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| − | * The surface of the foal's RBCs possess an antigen (usually Aa or Qa) that the mare's RBCs lack.
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| − | * The mare begins to mount an immune response towards the foal's RBCs.
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| − | * There are no antibodies against the foal's RBCs in the mare's colostrum as there has not been sufficient time to mount an immune attack and secrete them into the colostrum.
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| − | * The foal's intestine stops absorbing maternal antibodies after 30 hours (as previously discussed) and thus, when the alloantibody is secreted in the milk, it does not affect the foal.
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| − | '''Subsequent pregnancy from the same stallion or same blood group as previously exposed to'''
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| − | * Foal is born and suckles from the mare.
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| − | * Colostrum already contains alloantibodies against the foal's RBCs causing there to be RBC destruction or removal from the circulation [[Type II Hypersensitivity - WikiBlood|(type II hypersensitivity reaction)]] leading to haemolytic anaemia and jaundice.
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| − | * When the foal's intestines are no longer able to absorb maternal antibody (approximately 30 hours post partum) it is safe to return the foal to the mare.
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| − | Almost all mule pregnancys result in NI due to the mare lacking a factor called donkey factor.
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| − | =References=
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| − | Books
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| − | A.H. Andrewa '''Bovine Medicine - Diseases and Husbandry of Cattle''' Blackwell Publishing 2004 2nd Edition
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| − | Koterba, Drummound and Kosch '''Equine Clinical Neonatology''' Williams and Wilkins 1990
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| − | P. Lydyard, A. Whelan and M.W. Fanger '''Immunology''' Garland Science 2nd Edition 2004
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| − | Websites
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| − | www.sheepandgoat.com
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| − | [[Category:Materno-Fetal Immunity]]
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