Background The myeloperoxidase index (MPXI), on ADVIA hematology analyzers, reflects the mean neutrophil myeloperoxidase staining. It is used as a marker of inflammation in animals and people, but assay variability and storage stability are unknown. Objective We aimed to determine MPXI precision and stability with refrigerated storage of canine and equine EDTA‐anticoagulated blood and compared MPXI results between two analyzers. Methods Inter‐assay coefficients of variations (CVs) were determined from three human‐based controls assayed before and after a 20‐ or 21‐day calibration. Blood from 14‐16 dogs and 26 horses was assayed 4‐10 times within 1 day for intra‐assay CV measurements. Median control and single run results from 18 canine and 35 equine samples were compared between analyzers. Blood from 10‐12 dogs and 10‐11 horses was analyzed after collection, and 24, 48, and 72 hours of refrigerated storage. Results Inter‐assay CVs of controls were 10.7%‐15.9% and 6.4%‐9.6% before and 4.3%‐7.7% and 2.8%‐17.5% after calibration, for ADVIA 1 and 2, respectively. Calibration altered peroxidase gain settings and improved precision. Intra‐assay CVs were 0.6%‐64% and 3%‐350% for canine and equine samples, respectively. Median MPXI results differed significantly between the analyzers, likely from calibration‐associated changes in gains. MPXI decreased with storage, and with variable changes between animals and analyzers. Platelet clumps and lipid contributed to the variability in replicate MPXI measurements. Conclusion MPXI has a higher variability in equine samples than in canine samples. Equivalent results might not be obtained between analyzers. Results change unpredictably with repeated analyses over 72 hours. MPXI measurements might only be useful in controlled research settings.

Previous reports of leukemia in hedgehogs are limited. We describe clinicopathologic features of leukemia in 9 hedgehogs, including eosinophilic leukemia (n = 3) and acute leukemia/leukemic phase of lymphoma (n = 6). All 3 hedgehogs with eosinophilic leukemia were older than 2 years of age; in contrast, 4 of 6 cases of acute leukemia/lymphoma were <2 years old. Hedgehogs presented for non-specific clinical signs of anorexia and lethargy. On hematologic testing, hedgehogs with eosinophilic leukemia had a marked leukocytosis, consisting mostly of eosinophilic precursors with fewer mature eosinophils, whereas there were 43-97% immature cells (blasts) in the blood of hedgehogs with acute leukemia/lymphoma. Anemia (n = 6) and/or thrombocytopenia (n = 6) were concurrent findings. Increased liver enzyme activities (alanine aminotransferase, alkaline phosphatase) and hypoalbuminemia were the common findings on biochemical panels. All cases of eosinophilic leukemia and 4 cases of acute leukemia/lymphoma died shortly after diagnosis (median 7 days, range 0-41 days), whereas 2 cases of acute leukemia/lymphoma lived for 94 or 101 days. Postmortem examination in 5 cases (1 eosinophilic leukemia, 4 acute leukemia/lymphoma) showed bone marrow infiltrates, confirming eosinophilic leukemia and acute leukemia in 1 and 3 cases, and bone marrow necrosis in 1 animal with acute leukemia/lymphoma. Immunohistochemical staining of bone marrow sections confirmed a T-cell acute leukemia in 1 case. Several hedgehogs had concurrent carcinomas. Hedgehogs suffer from eosinophilic leukemia and acute leukemia/lymphoma. However, classification of acute leukemia by lineage was not possible due to lack of hedgehog cross-reactive or species-specific reagents.

A 12-y-old castrated male domestic longhaired cat had progressive paraparesis and neurolocalization of L4–S3. MRI revealed a circumscribed intradural-extraparenchymal mass from L5 to S1 that was T2 and short tau inversion recovery hyperintense and strongly contrast-enhancing. Cytologic interpretation of a blind fine-needle aspirate obtained through the L5–L6 space was a tumor of probable mesenchymal origin. A pair of suspect neoplastic cells was seen on a cytocentrifuged preparation of the atlanto-occipital CSF sample, despite a normal nucleated cell count (0 × 106/L) and total protein (0.11 g/L) with only 3 RBCs × 106/L. Clinical signs progressed despite increasing doses of prednisolone and cytarabine arabinoside. Repeat MRI on day 162 demonstrated tumor progression from L4 to Cd2 vertebral segments with intraparenchymal extension. Surgical tumor debulking was attempted, but an L4–S1 dorsal laminectomy revealed diffusely abnormal neuroparenchyma. Intraoperative cryosection favored lymphoma, and the cat was euthanized intraoperatively 163 d following presentation. Postmortem examination was performed, and the final diagnosis was a high-grade oligodendroglioma. This case illustrates the cytologic, cryosection, and MRI features of a unique clinical presentation of oligodendroglioma.