Changes

===Platelet Number===

===Platelet Number===

A platelet count can give valuable information in all critically ill animals and is an essential laboratory test for patients where there are concerns about abnormal bleeding. Platelet numbers may be rapidly estimated by examination of a stained blood smear, or quantified by manual or automated counting techniques. Platelet clumping can give an artificially low platelet count when using manual or automated counting methods. To estimate the platlet number using a blood smear, the slide should first be scanned for evidence of clumping that would artificially reduce the count. The average number of platelets in ten oil-immersion fields should be counted, and a mean calculated. Each platelet in a high-power field represents 15,000 platelets per microlitre². A "normal" platelet count therefore gives around 10-15 platelets per oil-immersion field.

A platelet count can give valuable information in all critically ill animals and is an essential laboratory test for patients where there are concerns about abnormal bleeding. Platelet numbers may be rapidly estimated by examination of a stained blood smear, or quantified by manual or automated counting techniques. [[Platelet_Abnormalities#Artefactual_or_spurious_thrombocytopaenia|Platelet clumping]] can give an artificially low platelet count when using manual or automated counting methods. To estimate the platlet number using a blood smear, the slide should first be scanned for evidence of clumping that would artificially reduce the count. The average number of platelets in ten oil-immersion fields should be counted, and a mean calculated. Each platelet in a high-power field represents 15,000 platelets per microlitre². A "normal" platelet count therefore gives around 10-15 platelets per oil-immersion field.

The reference range given for platelet number is usually around 200-500x10⁹ per litre, although this varies depending on the laboratory used. Clinical signs due to thrombocytopenia are not commonly encountered until the platelet count drops below 50X10⁹/l, when increased bleeding times may be seen. Haemorrhage during surgery becomes a concern with counts lower than 20X10⁹/l, and spotaneous bleeding arises when platelets are fewer than 5X10⁹/l². These cut-offs are lowered if platelet function is concurrently affected, for example by the use of non-steroidal anti-inflammatory drugs¹.

The reference range given for platelet number is usually around 200-500x10⁹ per litre, although this varies depending on the laboratory used. Clinical signs due to thrombocytopenia are not commonly encountered until the platelet count drops below 50X10⁹/l, when increased bleeding times may be seen. Haemorrhage during surgery becomes a concern with counts lower than 20X10⁹/l, and spotaneous bleeding arises when platelets are fewer than 5X10⁹/l². These cut-offs are lowered if platelet function is concurrently affected, for example by the use of non-steroidal anti-inflammatory drugs¹.