Epidemiologic survey of thrombocytopenia in dogs: a report on 987 cases

Thrombocytopenia was documented in 987 of 18,910 (5.2%) dogs admitted to North Carolina State University, College of Veterinary Medicine, Veterinary Teaching Hospital, between 1983 and 1989. Classifying thrombocytopenic dogs by etiologic groups revealed the following proportionate ratios: 5% (48/987) immune-mediated thrombocytopenia; 13% (130/987) neoplasia-associated thrombocytopenia; 23% (224/987) inflammatory/infectious thrombocytopenia; and 59% (585/987) miscellaneous thrombocytopenia. Dogs with immune-mediated thrombocytopenia had significantly (P < 0.05) lower platelet counts (mean 36,760 +/- 50,288 microliter) than dogs in the other three groups, and Doberman Pinschers were overrepresented in all groups except the immune-mediated thrombocytopenic group. We conclude that thrombocytopenia is a prevalent and potentially important diagnostic finding in a variety of disease states.     

Immune‐mediated hemolytic anemia and severe thrombocytopenia in dogs: 12 cases (2001–2008)

Objective – To identify and characterize the syndrome of immune‐mediated hemolytic anemia (IMHA) with concurrent severe thrombocytopenia (≤15.0 × 10⁹ platelets/L; [15.0 × 10³ platelets/μL]), and to evaluate prognostic factors, clinicopathologic findings, complications, treatment, outcome, and survival of dogs with this hematologic disorder. Design – Retrospective, observational study. Setting – Veterinary teaching hospital. Animals – Twelve client‐owned dogs with IMHA and severe thrombocytopenia (≤15.0 × 10⁹ platelets/L; [15.0 × 10³ platelets/μL]), without evidence of overt disseminated intravascular coagulation. Interventions – The following data were recorded and analyzed from the electronic medical record: signalment, history, concurrent diseases, clinical signs at presentation, clinicopathologic data, diagnostic testing, radiographic findings, treatment modalities, length of hospitalization, complications, and clinical outcome. All dogs were treated with immunosuppressive doses of corticosteroids. Measurements and Main Results – Twelve dogs were identified with the diagnosis of IMHA and severe thrombocytopenia; of these, 9 (75%) survived, 3 (25%) were euthanized, and none died. Dogs that survived were significantly younger than nonsurvivors (P=0.03). There were no specific clinical signs or therapies associated with survival. Conclusions – Dogs in this study had a mortality rate similar to reported rates for dogs with either disease alone. Overall, younger dogs were more likely to survive. No association between different treatment modalities and overall survival was identified.     

Effects of aspirin dose escalation on platelet function and urinary thromboxane and prostacyclin levels in normal dogs

Established “low” aspirin dosages inconsistently inhibit platelet function in dogs. Higher aspirin dosages consistently inhibit platelet function, but are associated with adverse effects. The objectives of this study were to use an escalation in dosage to determine the lowest aspirin dosage that consistently inhibited platelet function without inhibiting prostacyclin synthesis. Eight dogs were treated with five aspirin dosages: 0.5 mg/kg q24h, 1 mg/kg q24h, 2 mg/kg q24h, 4 mg/kg q24h and 10 mg/kg q12h for 7 days. Utilizing aggregometry and a whole‐blood platelet function analyzer (PFA‐100), platelet function was evaluated before and after treatment. Urine 11‐dehydro‐thromboxane‐B₂ (11‐dTXB₂) and 6‐keto‐prostaglandin‐F_1α (6‐keto‐PGF_1α), were measured. Compared to pretreatment, there were significant post‐treatment decreases in the maximum aggregometry amplitude and increases in the PFA‐100 closure times for all dosages expect 0.5 mg/kg q24h. There was no difference in amplitude or closure time among the 2 mg/kg q24h, 4 mg/kg q24h, and 10 mg/kg q12h dosages. Compared to pretreatment values, there was a significant decrease in urinary 11‐dTXB₂‐to‐creatinine and 6‐keto‐PGF_1α‐to‐creatinine ratios, but there was no dose‐dependent decrease for either metabolite. An aspirin dosage of 2 mg/kg q24h consistently inhibits platelet function without decreasing prostacyclin synthesis significantly more than lower aspirin dosages.     

Comparison of flow cytometry with the Sysmex XT2000iV automated analyzer for the detection of reticulated platelets in dogs

Background: Immature (reticulated) platelets (r‐PLT) are not routinely assessed by hematology analyzers, but may be useful in the evaluation of the bone marrow response to thrombocytopenia. Objective: The aim of this study was to compare the Sysmex XT2000iV hematology analyzer with standard flow cytometry for the determination of r‐PLT percentage in dogs. Methods: Blood samples were obtained from 40 healthy dogs, 12 thrombocytopenic dogs, and 6 dogs with normal platelet counts but with disorders associated with increased thrombopoiesis. The percentage of r‐PLT was determined with a FACscan flow cytometer (r‐PLT[F]) using CD61‐phycoerythrin antibody and thiazole orange, and with the PLT‐O channel of the Sysmex analyzer (r‐PLT[S]). Mean platelet volume, platelet distribution width, and platelet large cell ratio were also determined on the Sysmex. Repeatability (intra‐assay precision) and effect of storage were tested for the automated analyzer. Results: The reference interval (mean±1.96 X SD) for r‐PLT(F) was 1.91±1.29% (range 0.78–3.68%) and for r‐PLT(S) was 0.56±0.82% (range 0.11–2.16%). For both flow cytometry and the Sysmex, the patient group had a significantly higher mean percentage of r‐PLT compared with the control group (P<.0001, unpaired Student's t‐tests). Fair correlation (r=0.71; Spearman's regression analysis) was found for r‐PLT results between the 2 methods, and a negative proportional systematic bias of ?6.26 was found for the Sysmex (Bland–Altman analysis). Based on receiver operating characteristic curves and a cut‐off of ≥0.975%, a sensitivity of 94.7% and a specificity of 85.7% were obtained for detecting r‐PLT on the Sysmex, using flow cytometry as the reference method. Blood samples stored at 4 °C and 25 °C had a significant increase in the percentage of r‐PLT after 24 and 48 hours, respectively. Conclusions: The PLT‐O channel of the Sysmex XT2000iV is capable of detecting immature platelets in healthy, thrombocytopenic, and nonthrombocytopenic ill dogs.     

Precursor‐targeted immune‐mediated anemia in a dog with a stage IV mast cell tumor and bone marrow infiltration

A 12‐year‐old spayed female Shiba Inu dog was referred to our hospital for a suspected mast cell tumor (MCT) of the bone marrow (BM). Laboratory abnormalities included severe nonregenerative anemia (packed cell volume or PCV: 12.5%; reference interval (RI): 37.3‐61.7%; reticulocytes: 35.1 × 10³/µL; RI: 10‐110 × 10³/µL), and a few mast cells were visualized in the blood smear examination. The BM was hypercellular with hematopoietic cells, a decreased myeloid:erythroid (M:E) ratio (0.77; RI, 0.9‐1.8), and no dysplastic hematopoietic cells. Mast cells accounted for 11.5% of the total nucleated BM cells. Neoplastic mast cells and histiocytes phagocytizing erythroid progenitor cells were occasionally noted. The dog was diagnosed with precursor‐targeted immune‐mediated anemia (PIMA) concurrent and a stage IV MCT infiltrating the BM. Multimodal treatment included toceranib, imatinib, vinblastine, lomustine (CCNU), prednisolone, cyclosporine, mycophenolate mofetil, and a blood transfusion. The dog died due to MCT progression lasting 139 days after the initial BM examination. To the best of our knowledge, this is the first report of a dog presenting with PIMA and a stage IV MCT infiltrating the BM.     

Scoping review of quality of anesthetic induction and recovery scales used for dogs

ObjectiveTo compare, describe and assess the level of validation of all instruments measuring quality of induction and recovery from anesthesia in dogs.Databases usedA search was performed using the electronic database PubMed to find articles containing an induction quality scale, a recovery quality scale or both in dogs. Articles not directly accessible through PubMed were obtained through the Auburn University Library website and Google Scholar. The phrases ‘induction scoring systems dogs’, ‘recovery scoring systems dogs’, ‘anesthetic induction score dogs’, and ‘anesthetic recovery score dogs’ were used for searches using the ‘best match search’ function. The time frame searched was from 1980 to May 2020. The search was conducted from March 2020 to May 2020.ConclusionsA thoroughly tested and validated scale for measuring the quality of induction and recovery does not exist in the current veterinary literature. A large disagreement exists between studies on the use of induction and recovery scales, and many have reported inconsistent results with current instruments. It is recommended that an induction and recovery scale intended for wide-scale use be constructed and tested extensively for psychometric validation and reliability.     

Development of a limited‐sampling model for prediction of doxorubicin exposure in dogs

Understanding the relationship between drug dose and exposure (pharmacokinetics, PK) and the relationship between exposure and effect (pharmacodynamics) is an important component of pharmacology when attempting to predict clinical effects of anticancer drugs. PK studies can provide a better understanding of these relationships; however, they often involve intensive sampling over an extended period of time, resulting in increased cost and decreased compliance. Doxorubicin (DOX), one of the most widely used antineoplastic agents in veterinary cancer therapy, is characterized by large interpatient variability in overall drug exposure and the development and degree of myelosuppression following equivalent dosages. We have developed and validated a limited‐sampling strategy for DOX, in which three blood samples are obtained over 1 h post‐treatment, that accurately predicts patient exposure. This strategy could allow for refining of dosing variables and utilization of therapeutic drug monitoring to ensure optimized dosing.