Platelet Volume and Plateletcrit in Dogs with Presumed Primary Immune‐Mediated Thrombocytopenia

Abstract

BackgroundMean platelet volume (MPV) and plateletcrit (PCT) are indices used in evaluating immune‐mediated thrombocytopenia (IMT) in humans and in dogs with congenital macrothrombocytopenia. These indices may provide clinically valuable information in acquired thrombocytopenia.Hypothesis/ObjectivesDogs with presumed primary IMT will have increased MPV, and therefore platelet mass (PCT) will increase faster than platelet count (PLT) during recovery.AnimalsForty‐nine dogs with automated PLT < 30,000/μL because of presumed primary IMT and hematocrit (HCT), PCT, MPV, and platelet distribution width determined from the same complete blood count (CBC), and 46 healthy controls.MethodsCase‐control retrospective study; PLT, PCT, MPV, and platelet distribution width (PDW) were recorded from CBCs from 49 dogs, with 45 having data collected on the day of presentation. Fifteen were confirmed to have attained a PLT ≥ 75,000/μL on at least 1 CBC within 15 days after admission. The PCT equivalent to a PLT of 75,000/μL (assuming an average MPV) was calculated for comparison with PLT in terms of time to achieve a threshold of platelet mass by the 2 measures.ResultsMean platelet volume was higher in IMT dogs (17.3 fl) than the reference population (10.5 fl) (P < .0001). The PDW was not significantly different among the groups. The median time for PCT to reach threshold in confirmed responders was faster (3 days) compared with PLT (4 days).Conclusions and Clinical ImportanceImmune‐mediated thrombocytopenia is characterized by increased MPV. Time to achieve a threshold PCT tended to be shorter than PLT, suggesting that PCT may be a useful platelet parameter for monitoring dogs with IMT.

Intracorneal stromal hemorrhage in dogs and its associations with ocular and systemic disease: 39 cases

“…26 In addition, bleeding disorders such as immune-mediated thrombocytopenia directly impact primary hemostasis which will increase risk of spontaneous bleeding. 27 Hyperadrenocorticism may also play a role in hemostasis. It has been found that hyperadrenocorticism can cause a complex coagulopathy involving hypercoagulability and platelet hyporeactivity or dysfunction.…”

Detection and dynamics of anti‐platelet antibodies in thrombocytopenic dogs with and without idiopathic immune thrombocytopenia

“…In addition to platelet count, mean platelet volume (MPV) can be monitored; however, multiple mechanisms other than immune processes can result in an increased MPV so it is unlikely this can be used for determining relapse in dogs with ITP . Additionally, there are variable results as to whether dogs with idiopathic ITP consistently have an increased MPV . It is important to determine if a relapse is occurring because not only can life‐threatening bleeding events occur but it is important for appropriate case management and client communication.…”

Platelet indices in dogs with thrombocytopenia and dogs with normal platelet counts

“…An increased platelet size increases PDW levels just as an increased erythrocyte size increases RDW levels (Schwartz et al 2014). To our advantage, PDW can rise due to small variations in platelet morphology before MPV values are altered, similar to what occurs with the anisocytosis index, RDW, showing the greater sensitivity of PDW (Matos et al 2008).…”

“…Reinforcing this hypothesis, certain studies have already described how humans and dogs could respond to thrombocytopenia by increasing megakaryocyte numbers or by producing larger and more biologically active platelets (Minter andIngram 1971, Martin et al 1983). Schwartz et al (2014) suggested that presumptive primary immune-mediated thrombocytopenia in dogs is characterized by increased MPV levels due to large immature platelets` production during a regenerative process. However, this was not observed in our study.…”