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→Platelet Number
===Platelet Number===
===Platelet Number===
A platelet count can give valuable information in all critically ill animals and is an essential laboratory tests for patients with bleeding concerns. Platelet numbers may be rapidly estimated by examination of a stained blood smear, of quantified by manual or automated counting techniques. 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 microlitre<sup>2</sup>. A "normal" platelet count therefore gives aroung 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 with bleeding concerns. Platelet numbers may be rapidly estimated by examination of a stained blood smear, of quantified by manual or automated counting techniques. 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 microlitre<sup>2</sup>. A "normal" platelet count therefore gives around 10-15 platelets per oil-immersion field.
The reference range given for platelet number is usually around 200-500x10<sup>9</sup> 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 50X10<sup>9</sup>/l, when increased bleeding times may be seen. Haemorrhage during surgery becomes a concern with counts lower than 20X10<sup>9</sup>/l, and spotaneous bleeding arises when platelets are fewer than 5X10<sup>9</sup>/l<sup>2</sup>. These cut-offs are lowered if platelet function is concurrently affected, for example by the use of non-steroidal anti-inflammatory drugs<sup>1</sup>.
The reference range given for platelet number is usually around 200-500x10<sup>9</sup> 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 50X10<sup>9</sup>/l, when increased bleeding times may be seen. Haemorrhage during surgery becomes a concern with counts lower than 20X10<sup>9</sup>/l, and spotaneous bleeding arises when platelets are fewer than 5X10<sup>9</sup>/l<sup>2</sup>. These cut-offs are lowered if platelet function is concurrently affected, for example by the use of non-steroidal anti-inflammatory drugs<sup>1</sup>.