Romiplostim for treatment of thrombocytopenia in dogs: A retrospective assessment and clinical outcomes.

BACKGROUND: Romiplostim, a thrombopoietin analog, is commonly used to treat immune-mediated thrombocytopenia (ITP) in humans, but its use in dogs remains limited. OBJECTIVES: Evaluate the effects and adverse events of romiplostim administration in dogs with thrombocytopenia caused by various underlying diseases. ANIMALS: Forty-two client-owned dogs with naturally occurring thrombocytopenia at 2 referral animal hospitals. METHODS: Retrospective, multi-institutional analysis to evaluate the outcomes of romiplostim treatment in dogs. RESULTS: Among the dogs treated with romiplostim, 27 experienced an increase in platelet count and 26 maintained a platelet count within the reference range. Platelet count improvement was observed in various conditions: primary ITP (90%, n = 18/20), pancytopenia of unknown etiology (42.9%, n = 3/7), chemotherapy-induced thrombocytopenia (50%, n = 3/6), babesiosis (100%, n = 1/1), radiotherapy-induced thrombocytopenia (0%, n = 0/1), and disseminated intravascular coagulopathy (33.3%, n = 2/6). The median time for platelet recovery (>50 000/µL) after romiplostim administration was 4 days, and the median time for platelet count normalization was 7 days. Median hospitalization time for the improvement group (I) was 5 days. The survival-to-discharge rates were 85%, 40%, and 28.6% for dogs with primary ITP, secondary thrombocytopenia, and thrombocytopenia of unknown etiology, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Romiplostim is a well-tolerated and promising treatment for primary ITP in dogs, suggesting its potential as a valuable therapeutic option for dogs with thrombocytopenia caused by various underlying conditions. These findings emphasize the need for further research to optimize romiplostim dosing and understand its role in treating secondary thrombocytopenia and pancytopenia of unknown etiology.

Can neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios be used as markers for hypercortisolism in dogs?

Changes in neutrophil-to-lymphocite ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been identified in dogs with hypercortisolism (HC), but, no studies have investigated the changes in these inflammatory biomarkers as cost-effective and available parameters for the diagnosis and management of HC. This study was performed to evaluate whether NLR and PLR could be used as biomarkers for the diagnosis and treatment response in dogs with HC. This retrospective study included 67 dogs with HC, 58 dogs with non-adrenal illness (NAI), and 39 healthy dogs. NLR and PLR were compared among the three groups. Cut-off values of NLR and PLR for HC screening and percent change in biomarkers for assessing treatment response were evaluated. In addition, the NLR and PLR were compared before and after trilostane treatment. NLR and PLR were significantly higher in the HC group than in the NAI and healthy groups. The NLR cut-off value of 4.227 had a sensitivity of 67.16% and specificity of 65.52%, and the PLR cut-off value of 285.0 had a sensitivity of 56.72% and specificity of 70.69% for differentiating between dogs with HC and those with NAI, respectively. Furthermore, a significant decline in NLR was observed after treatment in the well-controlled HC group. The cutoff value of percent change in NLR to identify well-controlled HC was -7.570%; sensitivity and specificity were 100% and 63.64%, respectively. Therefore, NLR and PLR might be used cautiously as supportive biomarkers for HC diagnosis, and NLR could be a potential monitoring tool in assessing the treatment response of HC in dogs.

Evaluation of clopidogrel, hypercoagulability, and platelet count in dogs undergoing splenectomy for splenic masses.

Dogs that had splenectomy are predisposed to fatal thrombotic conditions, and thrombocytosis is a risk factor for post-splenectomy hypercoagulability. However, in veterinary medicine, there are no specific therapeutic approaches for managing this hypercoagulability. This study aimed to determine the preventive effect of clopidogrel on post-operative hypercoagulability during the first 2 weeks post-splenectomy in dogs with splenic masses. This study included 12 dogs that had splenectomy. Seven dogs received no treatment (group A), and five were treated with clopidogrel (group B). Clopidogrel was loaded at 10 mg/kg on day 2 and continued at 2 mg/kg until day 14. Blood samples were collected on the day of surgery and 2, 7, and 14 days after splenectomy in both groups. In group B, thromboelastography (TEG) was performed on the same days. In group A, there was significant elevation of platelet counts on days 7 (p = 0.007) and 14 (p = 0.001) compared to day 0. In group B, the platelet counts were significantly elevated on day 7 (p = 0.032) but no significant difference was found on day 14 compared to day 0. Platelet counts on day 14 were significantly higher in group A than in group B (p = 0.03). The lower platelet counts were correlated with alterations in TEG parameters, and no significant differences were found in the K and α-angle values at all postoperative assessment points compared to day 0. Our study suggests that clopidogrel may reduce post-operative thrombocytosis and hypercoagulability in dogs that undergo splenectomy for splenic masses.

Kanamycin treated-ethylenediamine tetraacetic acid-dependent pseudothrombocytopenia in blood specimen of cats.

Background: Pseudothrombocytopenia is a commonly obtained false negative result when analyzing feline platelet (PLT) count by an automated machine. It is related to ethylenediamine tetra-acetic acid (EDTA), a widely utilized anticoagulant in blood collection tubes, resulting in EDTA-dependent pseudothrombocytopenia (EDTA-PTCP). Aim: To investigate whether treated with kanamycin enhanced the quantity of PLT aggregations in feline blood specimens collected using EDTA-PTCP. Methods: Thirty-one blood samples were obtained using EDTA tubes. The complete blood count was analyzed using an automated Mindray BC-5000Vet. Both Manual cell counts and thin blood smears were performed to estimate the amount of red blood cell, white blood cell, and PLTs as well as to evaluate the severity scores of PLT clumping, respectively. Comparisons were made between those pre-treated and those treated with kanamycin in the EDTA tube. Results: There were significantly different mean PLT counts in the samples before and after they were treated with kanamycin, both on automated (156.6 ± 76.4 vs. 260.3 ± 115.5; p < 0.001) and manual (168.5 ± 92.1 vs. 262.8 ± 119.6; p < 0.001) readings, with a 95% confidence interval of 0.19 (0.022-0.365). Conclusion: This study suggests that in clinical laboratory practice, kanamycin should be added to feline blood specimens with EDTA-PTCP.

Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer's solution or 6% tetrastarch 130/0.4.

OBJECTIVE: To describe and compare prothrombin time (PT), activated partial thromboplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measurements in a hemorrhage/over-resuscitation model. DESIGN: Randomized crossover study. SETTING: University teaching hospital. ANIMALS: Six cats. INTERVENTIONS: Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR-no controlled hemorrhage and sham resuscitation; LRS-controlled hemorrhage and lactated Ringer's solution (LRS) for resuscitation; and Voluven-controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T - 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixed model approach (significance was P < 0.05). MEASUREMENTS AND MAIN RESULTS: Total median blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 and T120 compared to NHR (P < 0.001). On TEG, the reaction time, kinetic time, and alpha-angle were within reference intervals for cats at all time points in all treatments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, and T120 during Voluven and at T60 and T120 during LRS compared to NHR (both P < 0.001). The HCT and platelet count were significantly lower at T60 and T120 during LRS and Voluven compared to NHR (P < 0.001). CONCLUSIONS: Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strength may have been caused by hemodilution and platelet loss.

Evaluation of darbepoetin therapy on platelet count and function in healthy cats and cats with surgically induced chronic kidney disease.

OBJECTIVE: To evaluate the effects of darbepoetin on platelet population and reactivity in healthy cats (HCs) and azotemic cats with remnant kidney (RK) model-induced chronic kidney disease. ANIMALS: 12 purpose-bred domestic shorthair cats (n = 6 HCs and n = 6 RK). METHODS: In this pilot study, all cats received darbepoetin (1 µg/kg, SC) on days 0, 7, and 14. Blood was sampled at baseline and on days 3, 10, 15, 17, 20, and 21. At each time point, a CBC was performed, platelet aggregometry was assessed by impedance and optical methods, and platelet P-selectin (CD62P) was quantified before and after thrombin stimulation. Additionally, reticulated platelets were quantified using both thiazole orange staining and proprietary analysis by the CBC analyzer. For RK cats, systemic blood pressure (BP) was serially measured. RESULTS: No adverse effects of darbepoetin were seen. There was no statistically significant change in platelet count between or within groups at any time point. Hematocrit increased significantly over time in the RK but not the HC group. RBC reticulocyte numbers in both groups increased over time. Reticulated platelet percentage did not increase in either group. Differences in platelet reactivity within or between groups were not seen in the aggregometry or flow cytometric assessments. In RK cats, indirect BP did not significantly change during the study. CLINICAL RELEVANCE: This preliminary investigation did not find evidence that darbepoetin administration impacted platelet number, reactivity, nor reticulated platelet count. Anemic RK cats experienced increased hematocrit and RBC reticulocytes as expected with darbepoetin therapy.

Utility of immature platelet fraction in the Sysmex XN-1000V for the differential diagnosis of central and peripheral thrombocytopenia in dogs and cats.

BACKGROUND: The immature platelet fraction (IPF), a parameter obtained by the Sysmex XN-1000V analyzer, is used in humans to differentiate between central (CEN) and peripheral (PER) thrombocytopenia (TP) but has not been evaluated in small animals. OBJECTIVES: Compare IPF between healthy, clinical non-TP and TP dogs and cats, study IPF in different causes of TP in dogs and cats and, establish IPF reference intervals (RIs), and study the effect of age and sex on IPF in healthy dogs and cats. ANIMALS: A total of 3281 dogs and 726 cats. METHODS: Retrospective review of medical records. Animals were classified as nonthrombocytopenic (healthy group and group of clinical patients without TP [NTP]) or TP. These latter animals were subclassified as pseudothrombocytopenia (PSE), CEN and PER, based on evaluation of platelet clumps, estimated platelet count in blood smears and final diagnosis. Blood samples were evaluated using a Sysmex XN-1000V with a specific platelet channel (PLT-F). RESULTS: The IPF was significantly different between each subtype of TP in both species. Immature platelet fractions <6.9% in dogs or 13.6% in cats, once PSE has been eliminated by review of blood smears, are indicative of CEN. Reference intervals for IPF were 0.5%-8% in healthy dogs and 1%-40.3% in healthy cats. CONCLUSIONS AND CLINICAL IMPORTANCE: We determined that IPF can differentiate between CEN and PER in dogs and cats, guiding additional testing and avoiding more invasive procedures (bone marrow sampling). A blood smear always should be evaluated to rule out platelet clumping.

Effects of canine influenza infection and DA2PP vaccination on the development of platelet-associated immunoglobulins and platelet counts in dogs.

BACKGROUND: Immune thrombocytopenia (ITP) is commonly associated with platelet-associated immunoglobulins (PAIg). Demonstration of PAIg can help determine etiologies for thrombocytopenia. In humans, ITP and thrombocytopenia have been associated with various vaccinations and influenza infections, respectively. OBJECTIVES: We aimed to evaluate platelet counts and PAIg in research dogs with H3N2 and in research and client-owned dogs routinely vaccinated for distemper, adenovirus-2, parainfluenza, and parvovirus (DA2PP). The hypotheses were that H3N2 infection but not DA2PP vaccination would decrease platelet counts, and neither would result in the detection of PAIg. METHODS: Three pilot studies. Platelet counts and PAIg, measured by direct flow cytometry as %IgG, were evaluated in eight research Beagles following experimental infection with H3N2 (experiment 1), nine research Beagles vaccinated for DA2PP (experiment 2), and thirty client-owned dogs vaccinated for DA2PP (experiment 3). All animals were considered healthy at the start of the experiments. RESULTS: Transient, self-resolving decreases in platelet counts and increases in %IgG occurred following H3N2 infection, and one dog became thrombocytopenic and positive for PAIg. Following DA2PP vaccination, %IgG increased in research and client-owned dogs, but only one dog was considered positive for PAIg with a concurrent increase in platelet count. Mean PAIg increased from baseline in client-owned dogs following vaccination. CONCLUSIONS: Transient PAIg and thrombocytopenia can occur following H3N2 infection, while routine vaccination for DA2PP in this group of dogs was not associated with the development of thrombocytopenia or clinically relevant formation of PAIg.

Evaluation of platelet indices and complete blood count in canine mammary tumors

Malignant mammary tumors in humans and bitches cause hematological disorders such as anemia, erythrocytosis, thrombocytosis, hyperproteinemia, and leucopenia. Novel studies have been conducted on the predictive and prognostic values of platelet (PLT) indices in human breast cancer (HBC). However, there is little information about the alterations in hematological parameters in canine mammary tumors (CMTs). The aims of this study were to evaluate the platelet indices and complete blood count (CBC) parameters in bitches with and without mammary tumor and to assess the above mentioned parameters with regard to histological tumor types and grades. A total of 71 bitches were enrolled in this study. The bitches in the study group were divided into 2 groups which consisted of malignant epithelial mammary tumors (group EMT; n = 43) and malignant mixed mammary tumors (group MMT; n = 12). Control group (group C) consisted of clinically and gynaecologically healthy 16 bitches. Blood samples were obtained to perform the CBC and PLT indices analysis. Histopathological examinations were carried out under a light microscope. Histological tumor types and malignancy grades were classified. The bitches with mammary tumor showed significantly increased PLT values and decreased hematocrit (HCT), hemoglobin (HGB) and mean corpuscular hemoglobin (MCH) values versus the healthy ones, regardless of the tumor type. However, in comparisons with the group C, mean platelet volume (MPV) and mean corpuscular hemoglobin concentration (MCHC) values were different only in the group MMT, while plateletcrit (PCT) and mean corpuscular volume (MCV) values were different only in the group EMT. Also white blood cell (WBC), PLT and PCT values were higher than the referenced laboratory ranges in grade 3 tumors. In the presented study, MPV was considerably correlated with PLT, platelet distribution width (PDW) and PCT. Also, PCT and PLT had high sensitivity and specificity to distinct EMT and MMT from the healthy bitches. Microcytic and hypochromic anemia occurs due to the decrease in the amount of HGB. Levels of MCV, MCH, and MCHC in the HBC group were reported to be significantly lower than in humans without breast cancer. Although anemia did not occur in EMT and MMT groups, obtained significances in the HCT, HGB, MCV, MCH, and MCHC levels between the bitches with and without mammary tumor were in line with the previous reports. In this study, WBC levels in grade 3 tumors were significantly higher than grade1 tumors (P < 0.05). Whereas levels of WBC in grade 1 and grade 2 tumors were in referenced laboratory ranges, it was higher in grade 3. Increased level of WBC in grade 3 was supposed to be due to the rise in malignancy as previously reported. Thrombocytosis was detected in 48.83% and 41.66% of the bitches in EMT and MMT groups, respectively. The higher percentage of CMTs with thrombocytosis in this study might be due to the difference in referenced upper limit of PLT in previous studies. The elapsed time between tumor formation and clinical presentation could be another influencing factor. Although PLT and PCT values were not significant according to the histological grading in this study, both parameters were found to be higher in grade 3 than the normal reference values. Further studies conducted with higher populations may lead the differences in these parameters to significance. With the support of further studies, alterations in the above mentioned parameters in bitches may contribute in the diagnosis process, management of treatment and may constitute an easy way to have an idea about the prognosis of mammary tumors.(AU)

Protocols for preparation of platelet rich plasma (PRP) in Quarter Horses / Protocolos para o preparo de plasma rico em plaquetas (PRP) em cavalos Quarto de Milha

This study compared two protocols for preparation of platelet rich plasma (PRP) and evaluated the association between manual and automated methods for platelet count using a prospective study design. Eight clinically healthy Quarter Horses had venous blood samples collected at rest. After collection, blood samples were centrifuged twice, using two different protocols including a period of sample resting, either at the start or at the end of the protocol. Platelet counting at the start of the protocol, during, and after obtaining PRP was conducted manually or with an automated counter, followed by comparison of the two methods. In order to investigate platelet degranulation during the protocol, vascular endothelial growth factor (VEGF) was measured at each preparation stage. The protocol with sample resting before centrifugation yielded a more concentrated PRP, and the study verified that both manual and automated methods are comparable and can be used interchangeably for platelet counting. VEGF concentration did not differ significantly between protocols, or among protocol stages. The results indicate that choice of protocol for PRP preparation will affect the quantity of platelets in the final product, although platelet degranulation was not observed as evidenced by the stable VEGF concentrations measured. A larger yield of non-degranulated platelets in PRP is desirable since more α-granules will be present, therefore Protocol II is recommended. Both manual and automated counts reliably allow clinicians to obtain platelet counts and the choice of utilizing a manual or automated method is unlikely to interfere with evaluation of the final PRP product.(AU)

Este estudo comparou dois protocolos de preparo de plasma rico em plaquetas (PRP) e avaliou a associação entre dois métodos de contagem plaquetária - um manual e o outro automático através de um estudo prospectivo. Sangue venoso de oito equinos da raça Quarto de Milha foi coletado e em seguida foi centrifugado duas vezes utilizando-se dois protocolos distintos: um com descanso antes da primeira centrifugação e outro após a segunda centrifugação. A contagem plaquetária ao início, no meio e ao final dos protocolos foi realizada manualmente e pelo método automatizado, seguida de comparação entre os dois métodos. Para investigar a degranulação plaquetária ocorrida durante o preparo do PRP, o fator de crescimento vascular endotelial (VEGF) foi mensurado em cada estágio dos protocolos. O método utilizando o descanso da amostra antes da primeira centrifugação proporcionou a obtenção de um PRP mais concentrado, além de o estudo verificar que ambos os métodos de contagem plaquetária (manual e automatizado) são comparáveis e podem ser usados indiferentemente. A concentração de VEGF não foi significativamente diferente entre os estágios de preparo do PRP. Os resultados indicam que o método de preparo afeta a quantidade de plaquetas obtidas no PRP, apesar da degranulação plaquetária não ter sido observada, como evidenciado pela concentração estável de VEGF. Uma maior concentração de plaquetas no PRP é desejável, pois indica que um maior número de α-grânulos estará presente na amostra, portanto, conclui-se que o Protocolo II é mais recomendável. Tanto o método manual, quanto o automatizado, pode ser usado de maneira confiável para a contagem plaquetária, não interferindo com a avaliação do produto final (PRP).(AU)

Criopreservação do plasma rico em plaquetas de equinos / Equine platelet-rich plasma cryopreservation

Avaliou-se o congelamento do plasma rico em plaquetas (PRP) de equinos, a -196ºC em nitrogênio líquido, utilizando-se como crioprotetor o DMSO em duas concentrações (3% e 6%), e, como ponto final, a avaliação da morfologia e da agregometria plaquetária. Foram utilizadas 12 amostras de PRP em duas repetições. Previamente ao congelamento, as amostras foram submetidas a um resfriamento lento (-0,07ºC/minuto) até a temperatura final de 4-5ºC. A criopreservação do PRP equino, incluindo um resfriamento lento a 4-5ºC, previamente ao congelamento a -197ºC em nitrogênio líquido, foi similar para as concentrações do crioprotetor DMSO a 3% ou 6%, quando avaliado o percentual de ativação e de agregação plaquetária.

Equine platelet-rich plasma (PRP) frozen at -196°C in liquid nitrogen using DMSO as a cryoprotectant in two different concentrations (3% and 6%) was evaluated, using platelet morphology and aggregometry as the final parameters. Twelve PRP samples were used in two repetitions. The samples were submitted to slow cooling prior to frozen (-0.07°C/minute) until they reached the temperature of 4-5°C. Platelet cryopreserved in 3% or 6% DMSO, presented similar efficacy when the percentage of activation and platelet aggregation was evaluated.