Changes

==Description==

==Description==

Platelets (or thrombocytes) are responsible for primary haemostasis, the formation of a temporary platelet plug that initially seals any breach to a blood vessel wall.  Bleeding disorders may occur if platelets are deficient ('''thrombocytopaenia''') or if the platelets are unable to function adequately ('''thrombocytopathia''').  Thrombocytopaenia may be a '''primary disease''' due to disease of the bone marrow that reduces the production of platelets or it may occur '''secondary''' to another insult.

Platelets (or thrombocytes) are responsible for primary haemostasis, the formation of a temporary platelet plug that initially seals any breach to a blood vessel wall.  Bleeding disorders may occur if platelets are deficient ('''thrombocytopaenia''') or if the platelets are unable to function adequately ('''thrombocytopathia''').  Thrombocytopaenia may be a '''primary disease''' due to disease of the bone marrow that reduces the production of platelets or it may occur '''secondary''' to another insult.  '''Thrombocytosis''' refers to an increase in the blood platelet concentration above the normal level.

===Primary Thrombocytopaenic Disease===

===Primary Thrombocytopaenic Disease===

The aetiology of primary thrombocytopenic disease is often uncertain and it is therefore also known as '''idiopathic''' thrombocytopaenia.  Some cases of primary thrombocytopaenia may occur due to autoimmune responses directed at platelets and, although the [[Bone Marrow - Anatomy & Physiology|bone marrow]] may contain adequate normal megakaryocytes, this disease results in a reduced peripheral blood thrombocyte count.  [[Immune Mediated Thrombocytopaenia|Immune-mediated thrombocytopaenia]] occurs most commonly in young animals.

The aetiology of primary thrombocytopenic disease is often uncertain and it is therefore also known as '''idiopathic''' thrombocytopaenia.  Some cases of primary thrombocytopaenia may occur due to autoimmune responses directed at platelets and, although the [[Bone Marrow - Anatomy & Physiology|bone marrow]] may contain adequate normal megakaryocytes, this disease results in a reduced peripheral blood thrombocyte count.  [[Immune Mediated Thrombocytopaenia|Immune-mediated thrombocytopaenia]] occurs most commonly in young animals.

*Diseases that cause '''[[Bone Marrow - Anatomy & Physiology|bone marrow]] suppression'''

*Diseases that cause '''[[Bone Marrow - Anatomy & Physiology|bone marrow]] suppression'''

**'''Aplastic anaemia''' caused by ingestion of bracken, administration of oestrogens or of [[Chloramphenicol|chloramphenicol]] or [[Sulphonamides|sulphonamide]] antibiotics.  Prolonged use of phenylbutazone or salicylate may cause the same disease.

**'''Aplastic anaemia''' caused by ingestion of bracken, administration of oestrogens or of [[Chloramphenicol|chloramphenicol]] or [[Sulphonamides|sulphonamide]] antibiotics.  Prolonged use of phenylbutazone or salicylate may cause the same disease.

**'''Myelophthisis''', the displacement of the normal tissues of the bone marrow by another cell or tissue type may also reduce the function of the megakaryocytes.  Possible diseases include '''myelofibrosis''' and '''immunoprliferative''' or '''myeloproliferative''' neoplastic disease.

**'''Myelophthisis''', the displacement of the normal tissues of the bone marrow by another cell or tissue type may also reduce the function of the megakaryocytes.  Possible diseases include '''myelofibrosis''' and '''immunoproliferative''' or '''myeloproliferative''' neoplastic disease.

**'''Radiotherapy''' or myelosuppressive '''chemotherapy''' may cause reversible bone marrow suppression.

**'''Radiotherapy''' or myelosuppressive '''chemotherapy''' may cause reversible bone marrow suppression.

*Diseases that cause '''increased destruction of platelets'''

*Diseases that cause '''increased destruction of platelets'''

*Diseases that cause '''sequestration of platelets''' usually involve some enlargement to the spleen as this is the major organ where platelets are stored outside of the circulation.  Examples include:

*Diseases that cause '''sequestration of platelets''' usually involve some enlargement to the spleen as this is the major organ where platelets are stored outside of the circulation.  Examples include:

**[[Haemangiosarcoma]] of the spleen and liver

**[[Haemangiosarcoma]] of the spleen and liver

**Splenic enlargement under general anaesthesia with certain agents such as barbiturates and phenothiazines

**Splenic enlargement under general anaesthesia maintained with agents such as [[Barbiturates|barbiturates]] and [[Phenothiazines|phenothiazines]]

==Thrombocytopathia==

 

 

 

 

 

 

 

 

 

 

====Thrombocytopathia====

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Von Willebrands, Angiostrongylus, colloids, granule disease.

Von Willebrands, Angiostrongylus, colloids, Pelger Huet anomaly?.

* A rare inherited condition.

* A rare inherited condition.

* Recorded in the dog.   

* Recorded in the dog.   

** Poor aggregations.

** Poor aggregations.

** Poor platelet factor release.

** Poor platelet factor release.

[[Category:Haemorrhagic Diseases]]

[[Category:Haemorrhagic Diseases]]

[[Category:To Do - James]]

[[Category:To Do - James]]