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| + | ==Alloimmune haemolytic anaemia of the newborn== |
| − | Also known as: '''''Feline Neonatal Isoerythrolysis (FNI) — NI — Equine Neonatal Erythrolysis — ENI
| + | 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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| − | ==Introduction==
| + | 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. |
| − | Neonatal isoerythrolysis is a disease of humans and domestic animals and has been most commonly observed in newborn cats and horses. Rarely it has also been described in other species following [[:Category:Transfusion Medicine|blood transfusions]], [[Vaccines|vaccination]] or previous pregnancy. The disease is characterised by [[Immune Mediated Haemolytic Anaemia|immune-mediated haemolytic anaemia]] due to ingestion of maternal colostral antibody directed against surface antigens on neonatal red blood cells. This leads to a [[Type II Hypersensitivity|type II hypersensitivity]] reaction causing extravascular and intravascular haemolysis during the first few days of life.
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| − | ==Pathogenesis== | + | ==Neonatal Isoerytholysis (NI)== |
| − | ===Equine Neonatal Isoerythrolysis===
| + | Occurs in some foals, and always occurs in mules due to the incompatibility of the sire and dams blood types. |
| − | In foals, the condition results when a foal inherits red blood cell antigens (which the dam does not have) from its sire. The Aa and Qa antigens are most strongly antigenic and exposure of the mare to these antigens during a previous pregnancy or whole blood transfusion leads to the mare producing alloantibodies to the foal's red blood cells. At birth the foal ingests large numbers of red blood cell antibodies in the colostrum, leading to severe haemolytic disease. During pregnancy however, the foal is unaffected because blood and antibodies are unable to cross the placenta. First foals are rarely affected, as a sensitization reaction (usually during an earlier pregnancy) is usually required.
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| − | ===Feline Neonatal Isoerythrolysis===
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| − | [[Blood Groups - Cat|Cats have three main blood types]], type A, type B and type AB. Worldwide, the most common blood type in cats is type A and type A is dominant over type B. Queens with type B blood have high levels of naturally occurring alloantibodies to type A blood. Feline neonatal isoerythrolysis (FNI) develops when type B blood mothers mate with type A tomcats producing kittens with type A/B blood.
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| − | ==Clinical Signs==
| + | '''First pregnancy from a stallion with incompatible blood type to the mare:''' |
| − | ===Horses===
| + | * Mare is mated with a stallion with an incompatible blood type. |
| − | Affected foals appear clinically normal at birth, and clinical signs develop from several hours up to a week after ingestion of colostrum. Foals with NI usually become progressively weak, lethargic and depressed and develop [[icterus]], tachycardia and tachypnoea. Although the signs are not pathognomonic for NI, a foal displaying '''haemoglobinuria and icterus''' born to a multiparous mare should be strongly suspected to have the disease. If the foal becomes severely hypoxic, seizures may occur. '''Neurological abnormalities''', such as somnolence or seizures, may also occur due to the phenomenon of '''kernicterus'''. Excessive amounts of unconjugated bilirubin are able to cross the blood-brain barrier in foals and lead to a bilirubin encphalopathy which can be permenent. '''Death''' usually occurs if NI is not diagnosed and treated promptly.
| + | * The neonate may inherit the sire's blood type. |
| | + | * At parturition, or because of placentitis, RBCs from the foal enter the maternal circulation. |
| | + | * The surface of the foal's RBCs possess an antigen (usually Aa or Qa) that the mare's RBCs lack. |
| | + | * The mare begins to mount an immune response towards the foal's RBCs. |
| | + | * 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. |
| | + | * 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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| − | ===Cats===
| + | '''Subsequent pregnancy from the same stallion or same blood group as previously exposed to''' |
| − | Although FNI is rare, the mortality associated with the disease is high. Purebred cats are more commonly affected than domestic shorthair cats. Similarly to affected foals, kittens are born and nurse normally and clinical signs develop within a few hours or days. Signs may be variable and kittens are occasionally found dead within a few hours of the onset of clinical signs. Clinical signs may include failure to thrive, weakness, dark red/brown urine, icterus, and [[Regenerative and Non-Regenerative Anaemias|anaemia]]. Affected kittens may separate themselves from the rest of the litter, stop nursing and appear weak. Signs may vary in severity within a single litter; this is thought to be related to differences in colostral intake. Other features of the disease may include necrosis and sloughing of the tail tip and [[DIC|disseminated intravascular coagulation]]. Affected kittens rarely survive the first week of life.
| + | * Foal is born and suckles from the mare. |
| | + | * Colostrum already contains alloantibodies against the foal's RBCs causing there to be RBC destruction or removal from the circulation [[Type II Hypersensitivity|(type II hypersensitivity reaction)]] leading to haemolytic anaemia and jaundice. |
| | + | * 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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| − | ==Diagnosis==
| + | Almost all mule pregnancies result in NI due to the mare lacking a factor called donkey factor. |
| − | To definitively diagnose the condition in '''horses''', a minor cross-match is performed using the foal's red blood cells and the mare's serum. A positive agglutination indicates a diagnosis of NI.
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| − | In '''cats''', diagnosis is performed on the basis of clinical signs and blood typing of the queen and kitten. If FNI is suspected all kittens should be blood typed; this can be achieved using placental blood.
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| − | ==Treatment==
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| − | Treatment in '''foals''' depends on rapid identification of sick foals and prevention of suckling the dam for 48-72 hours. If the foal is less than 24 hours old at the time of diagnosis, it should be muzzled and fed supplemental milk. As the foal's intestine becomes impermeable to absorption of colostral antibodies by 24 hours of age, prevention of nursing until the foal is 30 hours of age should be sufficient. The mare should be milked every two hours during this period to ensure continued milk production. Separation of the mare and foal is not recommended as this may lead to unnecessary stress of the compromised foal.
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| − | A blood transfusion should be considered if the anaemia is severe (PCV less than 15%) or the foal is weak and shocked. The best donor of blood for transfusion is the dam, but this means that the serum containing the alloantibodies must be removed ('washing' of the red blood cells). This is achieved by mixing the mare's blood with saline and performing repeated centrifugation. If washed red blood cells from the mare are not available, blood from an acceptable blood-typed donor horse may be used.
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| − | Affected '''kittens''' should be removed from the queen for a period of 24 hours and fed milk replacer or fostered onto a lactating queen with blood type A. After this period, intestinal permeability to antibodies is greatly reduced and the kittens may be returned to the original queen. Supportive management of hypoglycaemia and hypothermia may be necessary. Severely affected kittens may require a blood transfusion, preferably with Oxyglobin if available. If this is not possible, washed type B blood is preferred. Intraosseous administration of blood is recommended due to the small size of the patient.
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| − | ==Prevention==
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| − | The disease in horses is prevented by ensuring that mares are blood-typed before being mated. Mares who are negative for the blood antigens known for causing disease can be matched to stallions who are also negative. Similarly in cats, the disease is easily prevented if blood typing of cats is peformed prior to breeding.
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| − | {{Learning
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| − | |flashcards = [[Equine Internal Medicine Q&A 09]]
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| − | |literature search = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=neonat*&occuring1=title&rowId=2&options2=AND&q2=%22isoerythrolysis%22&occuring2=title&rowId=3&options3=AND&q3=cats&occuring3=od&x=53&y=9&publishedstart=yyyy&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all Neonatal Isoerythrolysis in cats publications]
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| − | [http://www.cabdirect.org/search.html?q=title%3A%28neonat*%29+AND+title%3A%28%22isoerythrolysis%22%29+AND+od%3A%28horses%29 Neonatal Isoerythrolysis in horses publications]
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| | ==References== | | ==References== |
| − | Mair, T. S. (1998) '''Equine Medicine, Surgery and Reproduction''' ''Elsevier Health Sciences''
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| − | Norsworthy, G. D., Crystal, M., Grace, S. F. (2006) '''The Feline Patient''' ''Wiley-Blackwell''
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| − | Silvestre-Ferreira, A. C., Pastor, J. (2010) '''Feline Neonatal Isoerythrolysis and the Importance of Feline Blood Types''' ''Veterinary Medicine International Volume 2010''
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| − | {{review}}
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| − | {{OpenPages}}
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| − | {{Learning |Vetstream = [https://www.vetstream.com/equis/Content/Disease/dis00064.asp Neonatal Isoerythrolysis]}}
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| | [[Category:Materno-Fetal Immunity|E]] | | [[Category:Materno-Fetal Immunity|E]] |
| | [[Category:Immunological Disorders]] | | [[Category:Immunological Disorders]] |
| − | [[Category:Immunological Diseases - Horse]][[Category:Immunological Diseases - Cat]] | + | [[Category:Horse]] |
| − | [[Category:Expert Review]] | + | [[Category:To Do - Blood]][[Category:To Do - SophieIgnarski]] |
Alloimmune haemolytic anaemia of the newborn
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.
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.
Neonatal Isoerytholysis (NI)
Occurs in some foals, and always occurs in mules due to the incompatibility of the sire and dams blood types.
First pregnancy from a stallion with incompatible blood type to the mare:
- Mare is mated with a stallion with an incompatible blood type.
- The neonate may inherit the sire's blood type.
- At parturition, or because of placentitis, RBCs from the foal enter the maternal circulation.
- The surface of the foal's RBCs possess an antigen (usually Aa or Qa) that the mare's RBCs lack.
- The mare begins to mount an immune response towards the foal's RBCs.
- 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.
- 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.
Subsequent pregnancy from the same stallion or same blood group as previously exposed to
- Foal is born and suckles from the mare.
- Colostrum already contains alloantibodies against the foal's RBCs causing there to be RBC destruction or removal from the circulation (type II hypersensitivity reaction) leading to haemolytic anaemia and jaundice.
- 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.
Almost all mule pregnancies result in NI due to the mare lacking a factor called donkey factor.
References