Primary Immune-mediated Thrombocytopenia Research Articles

Retrospective evaluation of the short-term response of human intravenous immunoglobulin therapy in the management of canine immune-mediated thrombocytopenia (2010-2015): 27 cases.

To describe the short-term response, early prognostic markers, and survival after treatment of canine immune-mediated thrombocytopenia (ITP) with human intravenous immunoglobulin (hIVIG) and methylprednisolone. Retrospective cohort study. Private referral veterinary medical center. Twenty-seven client-owned dogs with primary or secondary ITP. All dogs received 2mg/kg IV methylprednisolone once daily and a single infusion of 5% hIVIG administered over 6-12hours. A substantial increase in platelet count within 60±12hours post-hIVIG infusion (T60) was observed in 19 of the 27 (70%) dogs with ITP (responders). Thirty-four variables, including serum immunoglobulin (Ig) G concentration 24±12hours post-hIVIG infusion (T24IgG) and increase in serum IgG concentration 24±12hours post-hIVIG infusion (T24ΔIgG), were compared between responders and nonresponders at 5 different time points. Mortality rates of responders and nonresponders were evaluated 14days post-hIVIG infusion. Serum T24IgG and serum T24ΔIgG were both significantly higher at T60 in responders. All responders were alive 14days post-hIVIG infusion, and their mortality rate was significantly lower compared with nonresponders. Responder dogs had an excellent 14-day survival rate. Serum T24IgG and serum T24ΔIgG concentrations accurately predicted response status at 60hours post-hIVIG infusion.

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

Romiplostim, a thrombopoietin analog, is commonly used to treat immune-mediated thrombocytopenia (ITP) in humans, but its use in dogs remains limited. Evaluate the effects and adverse events of romiplostim administration in dogs with thrombocytopenia caused by various underlying diseases. Forty-two client-owned dogs with naturally occurring thrombocytopenia at 2 referral animal hospitals. Retrospective, multi-institutional analysis to evaluate the outcomes of romiplostim treatment in dogs. 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. 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.

High Frequency of Genetic Variants Influencing Diagnosis and Bleeding Pattern in Patients with Presumed Primary Immune Mediated Thrombocytopenia (ITP)

Introduction Immune mediated thrombocytopenia (ITP) is a platelet disorder in which the immune system attacks and destroys the body's own platelets. Mechanisms leading to low platelet count in ITP are multifactorial, involving both increased peripheral platelet destruction and decreased platelet production. This is caused by autoantibodies targeting megakaryocytes and platelet-specific glycoproteins, as well as cytotoxic T cells directly acting on platelets. Although antibodies in some cases can be found in patients with ITP, there is no well-established diagnostic test and the diagnosis is thus, one of exclusion. While most cases of ITP resolve within 3 months with or without treatment, some patients do not respond to conventional treatment and develop a refractory ITP. It is likely that in the group of patients diagnosed with refractory ITP, some does not have an immune mediated thrombocytopenia, but other causes of low counts (PLC)s. With the development of high throughput sequencing and the increasing knowledge of inherited bleeding disorders, the possibility to identify the underlying cause of disease in these patients is steadily growing. In ITP, there is a high degree of interindividual differences in bleeding rates, where some patients have no bleeding symptoms despite of unmeasurable PLC, whereas other patients show severe bleeding symptoms at PLC > 30 x10 9 /L. The underlying etiology of these discrepancies is currently unknown and complicates the clinical care of these patients. We hypothesize that genetic defects influence the bleeding pattern in true ITP patients as well as being one of the underlying causes of thrombocytopenia in patients misdiagnosed with “refractory ITP”. The aim of this pilot study was to investigate whether upfront genetic screening of patients suspected of ITP could be a valuable diagnostic tool to determine presence of inherited thrombocytopenia, secondary thrombocytopenia and genetic variants that might affect bleeding pattern. Method Patients were included after informed consent following the declaration of Helsinki. We performed whole genome sequencing (WGS) in patients diagnosed with presumed ITP at the Skåne University Hospital, Sweden. Whole genome sequencing was performed at the Center for Genomic Medicine at Rigshospitalet, Copenhagen. An in-silico gene panel consisting of 113 genes known to be associated with bleeding disorders as well as 86 genes associated with ITP (Using the VarSeq gene prioritisation algorithm phorank) was analysed and pathogenicity was classified according to the ACMG/AMP guidelines. Patients' medical records were examined, laboratory work up was performed and clinical data regarding demographics and information regarding bleeding was collected. A final evaluation of susceptible variants took place at multiple disciplinary team conferences. Results Twenty-one patients were enrolled (9 women, 12 men, 17 were adults and 4 children). Mean age of adult patients was 50,5 years and mean age of paediatric patients was 11,5 years. Out of 21 patients, 7 were shown to have genetic variants with relevance to their disease. All variants were found in adult patients. Two patients had variants related to inherited thrombocytopenia (X-linked thrombocytopenia(WAS) and monoallelic Bernard-Soulier Syndrome(GP1BB)), 4 had variants in genes related to secondary ITP (3 with variants associated with common variable immunodeficiency (NFKB1, TNFRSF13B) and 1 with systemic lupus erythematosus (TREX1)) and 1 had a variant associated with platelet dysfunction (platelet delta storage pool deficiency (UNC13D)). Only the variant associated with X-linked thrombocytopenia was previously described (class 5) whereas the remaining 6 variants were initially classified as variants of unknown significance (VUS). Functional work-up and co-segregation studies indicated them as probably pathogenic (class 4) but confirming studies are still pending. Conclusion In this pilot study, 33% of patients with presumed primary ITP had variants with relevance to their clinical phenotype, and we were able to diagnose 1 patient with an inherited bleeding disorder (X-linked thrombocytopenia). Whole genome sequencing seems to be a useful diagnostic tool in the work up of patients with thrombocytopenia where ITP is suspected to ensure the diagnosis and could also add important information when assessing bleeding risk in individual patients.

Causes of thrombocytopenia in dogs in the United Kingdom: A retrospective study of 762 cases.

Thrombocytopenia is a common laboratory abnormality in dogs, and numerous diseases have been associated with its development. Estimates for the sensitivity and specificity of the degree of reduction of platelet concentration for the diagnosis of primary immune-mediated thrombocytopenia (pITP) have not been reported. To report the prevalence of different causes of thrombocytopenia in dogs in the United Kingdom and to investigate the utility of platelet concentration to differentiate causes of thrombocytopenia. Medical records of 762 dogs with thrombocytopenia presented to seven referral hospitals from January 2017 to December 2018 were retrospectively reviewed. Cases were assigned into the following categories: pITP, infectious diseases, neoplasia, inflammatory/other immune-mediated disorders and miscellaneous causes. The prevalence of the different categories was estimated, and platelet concentrations were compared. Receiver-operating characteristic (ROC) curves were used to investigate the utility of platelet concentration to differentiate between causes of thrombocytopenia. The most common disease category associated with thrombocytopenia was neoplasia (27.3%), followed by miscellaneous causes (26.9%), pITP (18.8%), inflammatory/immune-mediated disorders (14.4%) and infectious diseases (12.6%). Dogs with pITP had significantly lower platelet concentrations (median 8×109 /L, range: 0-70×109 /L) than dogs in the other four categories. Platelet concentration was useful for distinguishing pITP from other causes of thrombocytopenia (area under ROC curve=0.89, 95% confidence interval 0.87, 0.92), with a platelet concentration ≤12×109 /L being 60% sensitive and 90% specific. Severe thrombocytopenia was highly specific for a diagnosis of pITP, which was more prevalent in this UK population of thrombocytopenic dogs compared with previous epidemiological studies. Conversely, the proportion of dogs with infectious diseases was lower than in previous reports from other locations.

Retrospective evaluation of fresh platelet concentrate administration in dogs: Patient characteristics, outcomes, and transfusion practices in 189 transfusion episodes (2008-2019).

To describe patient characteristics, underlying disease processes, clinical outcomes, transfusion dose and type (therapeutic or prophylactic), platelet count changes, and adverse events associated with platelet concentrate (PC) administration in dogs. Retrospective study. University teaching hospital. A total of 149 dogs, representing 189 PC transfusion episodes. None. In this population, 39 of 149 dogs (26.2%) were diagnosed with primary immune-mediated thrombocytopenia, 22 of 149 (14.8%) had decreased bone marrow production, 12 of 149 (8.0%) received PC during a massive transfusion, 3 of 149 (2.0%) had congenital thrombocytopathia, 59 of 149 (39.6%) had severe thrombocytopenia of other causes, and 14 of 149 (9.4%) underwent transfusion for miscellaneous causes without a documented severe thrombocytopenia. In 117 of 149 dogs (78.5%), >1 site of hemorrhage was noted. The most common sites of hemorrhage were the gastrointestinal (GI) tract in 89 of 149 (59.7%) and the skin in 78 of 149 (52.3%). Overall survival to discharge was 59.1% (88/149). The median PC dose was 0.8 units per 10kg of body weight per transfusion episode (range: 0.2-6.7). Of 189 episodes, 29 of 189 (15.7%) were prophylactic, and 158 of 189 (83.6%) were therapeutic. For 99 of 189 transfusion episodes, paired pre- and postplatelet counts were available within 24hours. The median platelet count change was 5.0×109 /L (5000/μL; range: -115×109 /L to 158×109 /L [-115,000 to 158,000/μL]); the posttransfusion platelet count was significantly higher than pretransfusion (P<0.0001). The increase in platelet count after transfusion was greater in the prophylactic group than the therapeutic group (P=0.0167). Transfusion reactions were suspected during 2 of 168 episodes (1.2%). Immune-mediated thrombocytopenia was the most common disease process that resulted in PC transfusion. PC was more frequently administered to animals with active hemorrhage rather than prophylactically, and most dogs had evidence of hemorrhage in multiple organ systems, particularly the GI tract and skin. PC transfusions typically appeared safe, and the median platelet count increased after transfusion.

Canine immune-mediated thrombocytopenia

Immune-mediated thrombocytopenia (IMT) is a common disease in dogs. Primary IMT is idiopathic, while secondary IMT can result from a variety of infectious agents or some treatments. Symptoms may include lethargy, anorexia and mild pyrexia, together with a low platelet count and associated bleeding disorders. Prognosis is generally positive, but reduced with presence of melena or raised blood urea nitrogen. Treatment will include some form of immunosuppressive therapy, such as prednisolone, which can have multiple side effects. Nursing the IMT patient will aim at monitoring and reducing spontaneous haemorrhage and managing treatment side effects. To ensure owner understanding and compliance, it is vital to discuss these side effects and any appropriate home adjustments so an achievable plan can be developed for home care.

Long-term outcome of primary immune-mediated thrombocytopenia in dogs.

To determine the incidence of relapse after discharge from the hospital in dogs with a diagnosis of presumed primary immune-mediated thrombocytopenia, risk factors associated with relapse and whether or not indefinite use of immunosuppressive medication influences risk of relapse. Medical records from August 2007 through July 2016 were reviewed to identify dogs with a diagnosis of presumed primary immune-mediated thrombocytopenia. Data collection included signalment, initial diagnostic tests, treatment, incidence of relapse, survival duration and follow-up testing. A total of 45 dogs were diagnosed, treated and monitored for at least oneyear for presumed primary immune-mediated thrombocytopenia. 89∙6% of patients survived to discharge and 31% of those experienced a relapse following discharge. The median time from diagnosis to relapse was 79 days. Of dogs that experienced a relapse, 50% had at least one further relapse. There was no difference in age, body weight, gender, breed, platelet count at presentation, nadir packed cell volume during hospitalisation, incidence of melaena or initial treatment between the relapsing and non-relapsing groups. In the relapsing group, time to platelet recovery was significantly longer and these patients were more likely to have received a blood transfusion. This study does not provide evidence to support the use of long-term immunosuppressive medications to prevent relapse. However, the data suggest that patients with more severe disease at the time of diagnosis or that have already experienced a relapse should be monitored more closely.

Prevalence and disease associations in feline thrombocytopenia: a retrospective study of 194 cases

To assess the prevalence of thrombocytopenia in a referral population of cats in the UK, to identify disease processes associated with thrombocytopenia and to assess the proportion of thrombocytopenic cats that tested positive for feline leukaemia virus or feline immunodeficiency virus. Retrospective analysis of medical records at a UK referral hospital. Cats were grouped by mechanism of thrombocytopenia and disease process (where known). Prevalence of thrombocytopenia was 5·9%. The most common disease processes associated with thrombocytopenia were haematological or infectious disease and neoplasia; 11% of thrombocytopenic cats tested were positive for feline leukaemia virus, which is lower than reported previously. Cats presenting with unexplained haemorrhage had significantly lower platelet counts than other thrombocytopenic cats. Primary immune-mediated thrombocytopenia was less commonly diagnosed than in dogs and associated with the most severe platelet depletion in this study. Thrombocytopenia in cats may be more prevalent than previously reported and severe thrombocytopenia may be associated with spontaneous haemorrhage. Severe thrombocytopenia in cats appears less commonly immune-mediated than in dogs. Thrombocytopenia did not appear to be associated with retroviral infections.

Treatment of presumptive primary immune-mediated thrombocytopenia with mycophenolate mofetil versus cyclosporine in dogs.

The objective of this study was to compare hospitalisation duration, survival times, adverse events and cost of therapy in dogs with presumptive primary immune-mediated thrombocytopenia undergoing therapy with mycophenolate mofetil and corticosteroids versus cyclosporine and corticosteroids. A retrospective study of medical case records of dogs with presumed primary immune-mediated thrombocytopenia was conducted. Data collected included signalment, presenting complaints, haematologic and biochemical profiles, vector-borne disease testing, thoracic and abdominal radiographs, abdominal ultrasound, medications administered, duration of hospitalisation, 30- and 60-day survival, adverse events and cost of therapy. Variables were compared between dogs treated solely with mycophenolate mofetil and corticosteroids or cyclosporine and corticosteroids. A total of 55 dogs with primary immune-mediated thrombocytopenia were identified. Eighteen were excluded because multiple immunosuppressive medications were used during treatment. Hospitalisation times, 30-day survival and 60-day survival times were similar between both groups. Dogs in the mycophenolate mofetil/corticosteroid group experienced fewer adverse events than the cyclosporine/corticosteroid group. Therapy with mycophenolate mofetil was less expensive than that with cyclosporine. These results suggest that using the combination of mycophenolate mofetil and corticosteroids appears to be as effective as cyclosporine and corticosteroids in the treatment of presumed primary immune-mediated thrombocytopenia in dogs. Adverse events were less common and cost of therapy was lower in the mycophenolate mofetil group. Additional larger prospective, controlled, double-masked, outcome-based, multi-institutional studies are required to substantiate these preliminary findings.

Clinical data, clinicopathologic findings and outcome in dogs with amegakaryocytic thrombocytopenia and primary immune-mediated thrombocytopenia.

The aim of this study was to identify distinguishing characteristics between dogs diagnosed with amegakaryocytic thrombocytopenia and those diagnosed with presumed primary peripheral immune-mediated thrombocytopenia. Presenting clinical and clinicopathologic data and outcomes were compared between the two groups. Retrospective study performed on seven client-owned dogs diagnosed with amegakaryocytic thrombocytopenia and 34 client-owned dogs with primary peripheral immune-mediated thrombocytopenia. All dogs in the amegakaryocytic thrombocytopenia group were anaemic on presentation with a median haematocrit of 23% (range 9·4 to 36), while the primary peripheral immune-mediated thrombocytopoenia group had a median presenting haematocrit of 35% (range 10 to 53). Dogs with amegakaryocytic thrombocytopenia had a median of five (range 4 to 7) clinical signs of bleeding compared to a median of three (range 0 to 6) in the primary peripheral immune-mediated thrombocytopenia group with 86% (6 of 7) of amegakaryocytic thrombocytopenia dogs requiring a blood transfusion compared to 41% (14 of 34) of primary peripheral immune-mediated thrombocytopenia dogs. Six of the seven amegakaryocytic thrombocytopenia dogs did not survive to discharge, while only five of the 34 primary peripheral immune-mediated thrombocytopenia dogs did not survive to discharge. The clinical presentation of dogs with amegakaryocytic thrombocytopenia and primary peripheral immune-mediated thrombocytopenia is similar, but dogs with amegakaryocytic thrombocytopenia had a more severe clinical course compared to primary peripheral immune-mediated thrombocytopenia dogs. The prognosis for dogs with amegakaryocytic thrombocytopenia is poor.

Associação do sulfato de vincristina no manejo terapêutico da trombocitopenia imunomediada canina: relato de caso

A trombocitopenia imunomediada, destruição plaquetária mediada pelas respostas humoral e celular, é observada com frequência na espécie canina, especialmente nas fêmeas de meia-idade das raças spaniel e Doberman. A primeira linha terapêutica envolve a administração de corticoides em doses imunossupressoras e, nos casos refratários, a associação farmacológica a outros agentes imunomoduladores faz-se necessária. A presente descrição de caso objetiva relatar o sucesso na associação do sulfato de vincristina à corticoideterapia (Dexametasona), durante o período de hospitalização de cão com trombocitopenia imunomediada primária e sangramentos espontâneos relacionados, bem como discutir as modalidades terapêuticas presentes na literatura.

Frequencies of regulatory T cells in the peripheral blood of dogs with primary immune-mediated thrombocytopenia and chronic enteropathy: A pilot study

Regulatory T (Treg) cells are specialized immune cells with a pivotal role in the maintenance of immune homeostasis and control of inflammation. However, relatively little is known about immune regulation in the peripheral blood of dogs with primary immune-mediated thrombocytopenia or chronic enteropathy. Using flow cytometry this study investigated Treg responses in the peripheral blood of dogs with respective autoimmune or chronic intestinal diseases and demonstrated that a reduction of Treg frequencies is observed in dogs with clinical signs compared to dogs undergoing remission and healthy dogs. These findings suggest that reduced frequencies of Treg cells in peripheral blood might be causally associated with the onset and/or progression of autoimmune and chronic intestinal diseases in dogs and that measurement of regulatory T cells might represent a useful tool in the monitoring of treatment response and disease progression.

Platelet volume and plateletcrit in dogs with presumed primary immune-mediated thrombocytopenia.

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.

In this issue – July 2014

In this issue – <scp>J</scp>uly 2014

Primary Immune-Mediated Thrombocytopenia in Cats

Feline primary immune-mediated thrombocytopenia (pIMT) is a rare condition, and only a few cases have been described in veterinary literature. Five cats with severe thrombocytopenia most likely due to pIMT are described. A flow cytometry platelet-bound antibody test was positive in all cats; underlying diseases or triggering factors causing thrombocytopenia were not detected. Three cats were transfused with blood type-compatible fresh whole blood; one cat received Oxyglobin as well. All cats were treated with prednisolone; one cat received chlorambucil in addition. Four cats responded to treatment and were discharged from the hospital. One cat was euthanized due to dyspnea. Primary immune-mediated thrombocytopenia is rarely diagnosed in cats, but it is important as a differential diagnosis in cats presented with surface bleeding.

Underlying diseases and clinicopathologic variables of thrombocytopenic dogs with and without platelet-bound antibodies detected by use of a flow cytometric assay: 83 cases (2004–2006)

To characterize underlying diseases and clinical and clinicopathologic variables of thrombocytopenic dogs with and without platelet-bound antibodies (PBAs) and to evaluate clinicopathologic variables of dogs with primary immune-mediated thrombocytopenia (IMT). Retrospective case series. 83 thrombocytopenic dogs. Medical records were reviewed to identify dogs in which PBA tests were performed between 2004 and 2006; PBAs were measured via flow cytometry. PBAs were detected in 37 of 83 (45%) dogs. Thirteen dogs were suspected of having primary IMT. Median platelet counts were significantly lower in dogs with PBAs, compared with counts in dogs without PBAs. Dogs suspected of having primary IMT had significantly lower median platelet counts, compared with counts for those with secondary IMT. Mean platelet volume (MPV) was increased (> 14.3 fL) significantly more often in dogs without PBAs (19/33 [58%]) than in dogs with PBAs (7/26 [27%]). No dogs suspected of having primary IMT had an increase in MPV. Examination of bone marrow aspirates revealed an increase in megakaryopoiesis in a higher percentage of dogs with PBAs (14/21 [67%]) than in dogs without PBAs (7/18 [39%]). An increase in megakaryopoiesis was detected in all dogs suspected of having primary IMT that had a bone marrow analysis. Platelet counts, results of bone marrow analysis, and MPV may be helpful in dogs for the differentiation between primary IMT and thrombocytopenia resulting from other diseases. An MPV within or less than the reference range did not rule out an increase in megakaryopoietic activity.

A Prospective, Randomized, Double‐Blinded, Placebo‐Controlled Study of Human Intravenous Immunoglobulin for the Acute Management of Presumptive Primary Immune‐Mediated Thrombocytopenia in Dogs

Immune-mediated thrombocytopenia (IMT) is a common hematologic disorder in dogs. Human intravenous immunoglobulin (hIVIG) may have a beneficial effect in canine IMT. A single hIVIG infusion (0.5 g/kg) in dogs with presumed primary IMT (pIMT) is a safe adjunctive emergency treatment to accelerate platelet count recovery and shorten hospitalization time without increasing the cost of patient care. Eighteen client-owned dogs with a presumptive diagnosis of pIMT. Prospective, randomized, double-blinded, placebo-controlled clinical trial. There were no identifiable immediate or delayed adverse reactions associated with hIVIG administration over a 6-month period. The median platelet count recovery time for the hIVIG group was 3.5 days (mean + or - SD: 3.7 + or - 1.3 days; range, 2-7 days) and 7.5 days (mean + or - SD: 7.8 + or - 3.9 days; range, 3-12 days) for the placebo group. The median duration of hospitalization for hIVIG group was 4 days (mean + or - SD: 4.2 + or - 0.4 days; range, 2-8 days) and 8 days (mean + or - SD: 8.3 + or - 0.6 days; range, 4-12 days) for the placebo group. There was no significant difference between groups with respect to expense of initial patient care, whereas significant reduction in platelet count recovery time (P= .018) and duration of hospitalization (P= .027) were detected in the hIVIG group. Compared with corticosteroids alone, adjunctive emergency therapy of a single hIVIG infusion was safe and associated with a significant reduction in platelet count recovery time and duration of hospitalization without increasing the expense of medical care in a small group of dogs with presumed pIMT.

Primary Immune-mediated Thrombocytopenia in 30 Dogs (1997–2003)

During a 6-year period, primary (idiopathic) immune-mediated thrombocytopenia was retrospectively evaluated in 30 dogs. Ages of the dogs ranged from 3 months to 10 years (median 4 years); female dogs were markedly overrepresented with 73%. Clinical examination revealed hemorrhages in 70% of the dogs. Platelet counts ranged from 0 to 111,000/microL (median 8000/microL); 77% of the dogs had platelet counts <30,000/microL. Seventeen dogs were anemic (hematocrit 9% to 36%; median 31%). Immunosuppressive therapy was performed in all but one dog. The recurrence rate of 19 dogs that were followed over an extended period (112 to 1684 days; median 340 days) was 26%. Twenty-nine (97%) dogs survived 14 days after initial presentation, and 27 (93%) dogs survived at least the following 15 to 1684 days (median 220 days).

A retrospective study of 61 cases of spontaneous canine epistaxis (1998 to 2001)

To determine the prevalence and identify possible clinicopathologic indicators of the diseases associated with canine epistaxis. The medical records of 61 dogs with epistaxis were reviewed. Systemic diseases, diagnosed in fifty-six dogs, included canine leishmaniasis in twenty-three dogs, canine monocytic ehrlichiosis in twenty-two, concurrent canine leishmaniasis and canine monocytic ehrlichiosis in six, rodenticide toxicity in two and primary immune-mediated thrombocytopenia, suspected oestrogen toxicity and systemic arterial hypertension in one dog each. Intranasal diseases were documented in the remaining five dogs, including transmissible venereal tumour in three dogs, and nasal adenocarcinoma and nasal aspergillosis in one dog each. Mucosal pallor and a generalised bleeding tendency were significantly more common among dogs with canine monocytic ehrlichiosis compared with those with canine leishmaniasis, whereas the opposite was true for peripheral lymphadenomegaly. Also, dogs with canine monocytic ehrlichiosis presented with pancytopenia more frequently compared with those with canine leishmaniasis; in the latter dogs, the median values of haematocrit, leucocyte and platelet counts and serum total protein concentrations were higher. Canine leishmaniasis and canine monocytic ehrlichiosis are the leading causes of canine epistaxis in Greece. Mucosal pallor, bleeding tendency and pancytopenia are more likely to be indicative of canine monocytic ehrlichiosis, as opposed to peripheral lymphadenomegaly and hyperproteinaemia in canine leishmaniasis.

Treatment of Severe Immune‐Mediated Thrombocytopenia with Human IV Immunoglobulin in 5 Dogs

Background: Glucocorticoids with or without other immunotherapy are the initial treatment of choice for dogs with severe immune‐mediated thrombocytopenia (IMT). The majority of treated dogs will have improvements in platelet counts within 5 to 7 days of starting therapy, but complications from hemorrhage often occur before a response is seen. Human IV immunoglobulin (hIVIG) blocks Fc receptors on mononuclear phagocytic cells in dogs; it is used in people with idiopathic thrombocytopenic purpura.Hypothesis: The purpose of this study was to describe adverse effects and benefit of hIVIG in addition to conventional immunosuppressive therapy in dogs with severe IMT.Animals: Five client‐owned dogs with severe primary IMT.Methods: Case series. The hospital database was searched for dogs with primary IMT treated with hIVIG.Results: No adverse effects were noted during or after hIVIG infusion in any treated dog. Over a 6‐month follow‐up, all dogs were clinically normal when using conventional immunosuppressive therapy. Human IVIG was administered 3 days after initiation of immunosuppressive therapy in 4 dogs, and, after 2 days, in 1 dog. In all dogs, the mean platelet counts pre‐and 24 hours post‐hIVIG infusion (0.28–0.76 g/kg) were 2,500/μL and 50,600/μL (62,750/μL for the 4 responders), respectively. One dog failed to respond as promptly to hIVIG (0.34 g/kg), and the platelet count increased to 66,000/μL after 9 days of immunosuppressive therapy. The mean duration of hospitalization post‐hIVIG in all 5 dogs was 1.8 days (12 hours for responders), and the mean total length of hospitalization was 4.6 days (3.5 days for responders). Active hemorrhage resolved and no packed red blood cell transfusions were required after hIVIG infusion for responders.Conclusions and Clinical Importance: Human IVIG was well tolerated and appeared to be associated with rapid platelet count recovery and amelioration of clinical signs in most dogs with IMT.