Practical Matters: Recheck low platelet counts in asymptomatic patients

Of all the values on a general blood panel (complete blood count, serum chemistry profile), the platelet count may have the greatest potential to fool you. I have had several patients referred for severe thrombocytopenia that had normal platelet counts when I rechecked their complete blood counts. The problem is that blood clots and platelet clumps can dramatically lower the manual and automated counts. Usually, the laboratory will comment on platelet clumps, but occasionally the clumps are either not reported or seem to have been missed.

Todd Deppe, DVM, DACVIM

In all the cases mentioned above, the animals had no clinical signs of thrombocytopenia. With these patients in mind, my advice is if an animal has signs of spontaneous bleeding (petechia, hematuria, hematochezia or melena, prolonged bleeding from venipuncture sites), believe the first low platelet count and take appropriate action. But if an animal has no clinical signs of thrombocytopenia, recheck the platelet count before performing an extensive workup or initiating treatment. Recheck the platelet count quickly (the next day if possible) because the consequences of waiting too long to treat a patient with thrombocytopenia are potentially severe. If a laboratory is not immediately available, a high-quality blood smear read in-house by an experienced person can provide inexpensive, rapid confirmation of severe thrombocytopenia.

Todd Deppe, DVM, DACVIM (internal medicine)

Veterinary Medical and Surgical Group

2199 Sperry Ave.

Ventura, CA 93003