Immature platelet fraction and reticulated platelet parameters as potential indicators of bone-marrow-related platelet production in dogs and cats: A scoping review

Background Evaluating bone marrow is an invasive and expensive procedure that frequently necessitates sedation or anesthesia in dogs and cats. The immature platelet fraction (IPF(and related immature or reticulated platelet parameters, has been suggested as a non-invasive alternative for assessing megakaryocytic activity. However, a comprehensive assessment of the depth and balance of evidence across the two most prevalent companion animal species has not been conducted previously. Objective Aim of this scoping review was: (1) to map and classify primary studies that report on IPF or reticulated platelets in the context of thrombopoietic activity or bone-marrow activity in dogs and/or cats, (2) to classify the subjects, assays, reference criteria, clinical information, findings etc; and (3) to highlight principal evidence gaps and identify if the evidence generated is adequate and comparable for the systematic review or for a future meta-analysis. Methods Following the Population-Concept-Context (PCC) framework and the PRISMA Extension for Scoping Reviews (PRISMA-ScR guidelines, an exhaustive search was conducted in PubMed/MEDLINE, Web of Science, Scopus, and CAB Abstracts. The parameters of immature and reticulated platelets have been examined in relation to bone marrow and platelet status. Records were reviewed to ensure eligibility, and a standard data sheet was used to extract data. Results Of 35 records identified, 10 met the eligibility criteria. Nine of the ten included studies reported data only in dogs; a single retrospective study reported data in both dogs and cats, and no study addressed cats exclusively. Only one study used a direct bone-marrow reference standard (megakaryocyte cytology); the remainder relied on indirect or clinical classification. Conclusions Evidence for IPF/reticulated platelets as a bone-marrow marker is considerably more developed in dogs than in cats. Feline data are essentially limited to a single retrospective analyzer study. Given the small number of studies and marked methodological heterogeneity, a full systematic review with meta-analysis is not currently feasible; a scoping review is the appropriate and informative synthesis at this stage.