Blood calcium, glucose and haematology profiles of parturient bitches diagnosed with uterine inertia or obstructive dystocia.

Bitches with dystocia most often present with clinical signs of uterine inertia (UI). The aetiology of myometrial dysfunction in most of these cases is still not elucidated. We compared blood ionized calcium (iCa) and glucose concentrations in bitches diagnosed with primary UI (PUI, n = 14), secondary UI (SUI, n = 6) or obstructive dystocia (OD, n = 6), and we described their haematology profiles. Bitches diagnosed with UI had a patent birth canal and delivered no puppies yet (PUI) or only part of the whole litter (SUI). The OD group had no UI and showed strong abdominal contractions. Blood iCa did not differ between the PUI, SUI and OD groups and was not influenced by litter size. There was a significant positive relationship (R2  = .241, p = .013) between iCa concentrations and the dam's body weight. Glucose concentrations were also not significantly different between dystocia groups or influenced by body weight and litter size. Hypocalcaemia was detected in 11 bitches, and hypoglycaemia in two bitches. Pregnancy-associated anaemia was seen in about one-third of the bitches. Eight of 12 dogs had increased platelet counts, and ten had leukocytosis with mature neutrophilia. Although iCa did not differ between dystocia groups, low concentrations may have contributed to the development of UI in some of the small size bitches. Hypoglycaemia was uncommon, and therefore, we consider low glucose concentrations not to have played an important role in the pathogenesis of UI in our study population. Pregnancy-associated anaemia, thrombocytosis, leukocytosis and mature neutrophilia were common findings in otherwise healthy bitches diagnosed with different forms of dystocia.

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.

Starvation and the clinicopathologic abnormalities associated with starved dogs: a review of 152 cases.

The objectives of this retrospective study were to identify the most common clinicopathologic abnormalities in starved dogs, assess the time required for those abnormalities to resolve, and determine whether clinicopathologic abnormalities recorded at time of intake to the hospital influenced time to regain weight. Records of 152 very underweight or emaciated dogs seized by the American Society for the Prevention of Cruelty to Animals (ASPCA) Humane Law Enforcement (HLE) division were reviewed. Dogs were classified as emaciated if the admission body weight was estimated to be ≥ 30% below the anticipated ideal body weight and classified as very underweight if the admission weight was estimated to be 20-29% below the anticipated ideal body weight. An initial minimum database was obtained on each animal, and when possible, clinicopathologic abnormalities were serially assessed. The most common initial abnormalities, present in ≥ 25% of dogs, were hypoalbuminemia, thrombocytosis, anemia, elevated blood urea nitrogen (BUN), elevated BUN/creatinine ratio, and hypocalcemia. Mean time to gain 20% of admission body weight was similar for the abnormalities studied. Although there was some evidence that dogs with anemia and/or hypoalbuminemia required more days to gain weight, future studies are required for confirmation.

Thrombocytosis in 158 cats (2011-2018).

OBJECTIVES: Thrombocytosis is an uncommon hematologic abnormality that is associated with various physiologic, metabolic, inflammatory and neoplastic conditions in people and dogs. Thrombocytosis is not a well-described abnormality in cats. The objective of this study was to classify thrombocytosis in cats based on underlying disease processes and severity, and to compare this with a control population of cats. METHODS: A retrospective study was conducted by reviewing the medical records of cats with increased (>600 × 103/µl; thrombocytosis group) and normal (200-600 × 103/µl; 2:1 age-matched control group) platelet counts between 2011 and 2018. Platelet counts were estimated based on blood smear assessment in all cats. Cats were classified by the severity (mild, moderate or marked) of thrombocytosis. Diagnoses were recorded for all cases, and were classified broadly into either neoplasia, endocrine or inflammatory disease. RESULTS: In total, 158 cats were identified with thrombocytosis, with 315 cats in the control group. Non-neoplastic inflammatory disease was the most common diagnosis in both groups (54.4% in cats with thrombocytosis and 56.2% in controls; P = 0.77); however, gastrointestinal diseases were more common in cats with thrombocytosis (75.6%) when compared with controls (34.5%; P <0.0001). Neoplasia was diagnosed more frequently in cats with thrombocytosis (44.3%) compared with the control group (25.4%; P <0.0001). Round cell tumor was the most common neoplasia diagnosis in both groups, but gastrointestinal and multicentric lymphoma were diagnosed more frequently in cats with thrombocytosis compared with control cats. No association between the severity of thrombocytosis and etiology was identified. CONCLUSIONS AND RELEVANCE: Thrombocytosis in cats is more commonly associated with gastrointestinal, hepatobiliary or immune-mediated diseases when compared with a control population. Neoplasia, especially multicentric and gastrointestinal lymphoma, was more commonly diagnosed in cats with thrombocytosis when compared with control cats.

Interleukin-6 and thrombopoietin concentrations in dogs with carcinoma with and without thrombocytosis.

BACKGROUND: Carcinoma-associated thrombocytosis involves tumor production of mediators such as interleukin-6 (IL-6) and thrombopoietin (TPO) that increase thrombopoiesis and may play a role in tumor evasion and metastasis. Carcinoma-associated thrombocytosis is described in people, but has not been described in dogs. HYPOTHESIS/OBJECTIVES: Evaluate the concentrations of IL-6 and TPO in dogs diagnosed with carcinoma with or without thrombocytosis. We hypothesized that IL-6 and TPO concentrations would be higher in dogs with carcinoma compared to healthy dogs, and that IL-6 and TPO concentrations would be higher in dogs with carcinoma and thrombocytosis when compared to dogs with carcinoma and normal platelet counts. ANIMALS: One-hundred sixteen dogs: 63 with carcinoma and 53 healthy control dogs. METHODS: Complete blood count was performed in all dogs, and they were stratified for sub-group analysis based on the presence or absence of thrombocytosis (platelet count > 500 103/µL). Serum TPO and IL-6 concentrations were measured by ELISA. Results of selected numeric variables were compared using Wilcoxon rank sum tests for pairwise comparisons. A value of P < .05 was considered significant. RESULTS: Twelve of the dogs with carcinoma (12/63, 19.0%) and none of the healthy control dogs (0%) had thrombocytosis. Thrombopoietin concentrations (median [range]) were significantly higher in dogs with carcinoma when compared to controls (87.42 pg/mL [0 to >600] vs 15.99 pg/mL [0 to >600], P < .001). Interleukin-6 concentrations (median [range]) were not different between dogs with carcinoma and healthy control dogs (9.70 pg/mL [0-181.53] vs 3.03 pg/mL [0-280.77], P = .15). In dogs with carcinoma, the TPO and IL-6 concentrations were not different between dogs with thrombocytosis and dogs with normal platelet count. CONCLUSIONS AND CLINICAL IMPORTANCE: Thrombopoietin concentrations were significantly higher in dogs with carcinoma, regardless of platelet count. Thrombopoietin is likely to be 1 of multiple factors that can impact platelet number, production, and consumption in dogs with carcinoma.

Postoperative thrombocytosis and thromboelastographic evidence of hypercoagulability in dogs undergoing splenectomy for splenic masses.

OBJECTIVE: To determine the frequency and severity of thrombocytosis and thromboelastographic evidence of hypercoagulability during the first 2 weeks after splenectomy in dogs with splenic masses and to investigate relationships between platelet counts and thromboelastography values. ANIMALS: 34 dogs undergoing splenectomy for splenic masses. PROCEDURES: Blood samples for platelet counts and thromboelastography were obtained at induction of anesthesia (day 0) prior to splenectomy and on days 2, 7, and 14. RESULTS: Mean platelet counts were 167.9 × 103/µL, 260.4 × 103 µ/L, 715.9 × 103/µL, and 582.2 × 103/µL on days 0, 2, 7, and 14, respectively, and were significantly higher at all postoperative assessment points than on day 0. Thrombocytosis was observed in 3% (1/34), 6% (2/33), 81% (21/26), and 69% (18/26) of dogs on days 0, 2, 7, and 14. Platelet counts > 1,000 × 103/µL were observed in 1 dog on day 2 and in 5 dogs on day 7. One or more thromboelastography values suggestive of hypercoagulability were observed in 45% (15/33), 84% (26/31), 89% (24/27), and 84% (21/25) of dogs on days 0, 2, 7, and 14. At each assessment point, higher platelet counts were correlated with thromboelastography values suggestive of hypercoagulability. CONCLUSIONS AND CLINICAL RELEVANCE: Marked thrombocytosis and thromboelastography values suggestive of hypercoagulability were common during the first 2 weeks after splenectomy for the dogs of this study. If present, hypercoagulability could increase the risk for development of postsplenectomy thrombotic conditions such as portal system thrombosis and pulmonary thromboembolism.

Thrombocytosis and central nervous system involvement in a case of canine acute megakaryoblastic leukemia.

This case report presents a 14-month-old female Poodle mix with acute megakaryoblastic leukemia based on a marked thrombocytosis, abnormal platelet morphology, circulating dwarf megakaryocytes, and blast cells in the blood. Bone marrow abnormalities included dysmegakaryopoiesis dygranulopoiesis, and an increased number of blast cells was observed in the blood. Extensive leukemic involvement was also found in the liver, spleen, lymph nodes, lungs, kidneys, and brain. The cytopathologic features of the abnormal circulating cells were highly suggestive of being megakaryocytic in origin, which was supported by negative myeloperoxidase staining and positive von Willebrand factor staining on immunocytochemistry (ICC). The neoplastic cells were also CD61 positive and had variable von Willebrand factor expression on ICC. Although there were only 25% blast cells in the bone marrow, which theoretically supported myelodysplastic syndrome, the hypothesis that this case represented acute myeloid leukemia of megakaryoblastic origin was confirmed by the continuous increase in circulating blast cell numbers during follow-up visits and the extensive leukemic involvement of parenchymal organs.

Thrombocytosis in cats: a retrospective study of 51 cases (2000-2005).

Feline haematology profiles of patients presented to the University of Bristol Small Animal Hospital from January 2000 to October 2005 were evaluated for thrombocytosis (defined as a platelets count of >700x10(9)/l and confirmed on smear evaluation). Thrombocytosis was found in 79 cats (4.64% of the hospital feline population), with values ranging from 703 to 1895x10(9)/l. Signalment, clinical presentation, concurrence of other haematological abnormalities, diagnoses and outcome were evaluated in 51 cases in which complete medical records were available. Other variables (feline immunodeficiency virus/feline leukaemia virus status, thyroxine level, haemoplasma PCR, toxoplasma antibody titres) were also evaluated. No association was found between the presence of thrombocytosis and breed or gender. Gastrointestinal signs were the most common clinical presentation. Lymphopenia was the most common concurrent haematological abnormality. Based on final diagnosis reached, cats were grouped both according to the DAMNITV classification and according to the body system affected. Amongst the DAMNITV classification, inflammatory/infectious conditions were most commonly associated with thrombocytosis. According to body systems, gastrointestinal involvement was most represented, followed by endocrine cases. No association was found between the severity of thrombocytosis and outcome.

Magnitude of reactive thrombocytosis and associated clinical conditions in dogs.

Previous studies on the underlying causes of thrombocytosis have raised scientific interest in its clinical relevance in dogs. The purpose of this study was: (1) to explore the clinical conditions associated with thrombocytosis; (2) to compare platelet counts among these conditions; and (3) to identify possible interactions with other haematological variables and associated conditions. Medical records of 195 dogs with thrombocytosis (platelet count >500×103/µL) were reviewed for signalment, complete blood count results and definitive diagnosis. The prevalence of thrombocytosis was 6.02%. All cases included had reactive thrombocytosis, with non-neoplastic, non-inflammatory underlying conditions in 48.2%, inflammatory processes in 34.4% and neoplastic processes in 17.4%. Haemoglobin and white blood cell counts were negatively and positively associated with platelet count, respectively. This study revealed that mean platelet count in dogs with neoplasia and a packed cell volume of 35% or below was significantly higher than that for dogs with other disease categories. Therefore, for dogs with marked thrombocytosis and anaemia, it is recommended that neoplasia should be included in the list of differential diagnoses.

Thrombocytosis in 715 Dogs (2011-2015).

BACKGROUND: Thrombocytosis is a hematologic abnormality in dogs that has been associated with various neoplastic, metabolic, and inflammatory conditions. OBJECTIVE: To classify thrombocytosis in dogs based on severity and evaluate whether there are associations between severity and underlying disease processes. ANIMALS: Seven hundred and fifteen dogs with thrombocytosis and 1,430 dogs with normal numbers of platelets. METHODS: Retrospective study. Medical records of dogs with increased (>500 × 103 /µL; thrombocytosis group) and normal (300-500 × 103 /µL; control group) platelet counts between 2011 and 2015 were reviewed. Dogs were characterized by severity of platelet increase and diagnosis. Diagnostic categories included neoplasia, endocrine disease, inflammatory disease, or miscellaneous. RESULTS: A total of 1,254 complete blood counts with thrombocytosis from 715 dogs were included in the study. Median platelet count in this population was 582 × 103 /µL (500-1,810 × 103 /µL). No correlation between severity of thrombocytosis and diagnosis was identified. Causes of secondary thrombocytosis included neoplasia (55.7%), endocrine disease (12.0%), and inflammatory disease (46.6%). Immune-mediated disease was common (22.2%), associated with frequent glucocorticoid administration, and had a significantly higher median platelet count (636 × 103 /µL [500-1,262 × 103 /µL] versus 565 × 103 /µL [500-1,810 × 103 /µL]) when compared to the other inflammatory processes (P < 0.001). The diagnoses in the thrombocytosis dogs differed significantly from the control population (P < 0.001). CONCLUSIONS AND CLINICAL IMPORTANCE: Thrombocytosis is commonly associated with carcinoma and immune-mediated disease in dogs.

[Effects of different liver diseases on the platelet count in dogs]. / Auswirkungen unterschiedlicher Lebererkrankungen auf die Thrombozytenzahl beim Hund.

Changes of the platelet count in liver diseases are described in humans. Thrombocytopenia was observed more frequently than thrombocytosis. There are only a few investigations on platelet counts in liver diseases in dogs. The goal of the present study was to investigate the influence of different liver diseases including degeneration, hepatitis and liver tumours, on the platelet count. Platelet counts of 52 dogs with different liver diseases were measured and compared with 52 healthy dogs. The results showed, that dogs with liver degeneration have thrombocytosis in 41% of the cases and a group of dogs with liver tumours (malignant histiocytosis, hepatoma, malignant lymphoma anaplastic sarcoma, cholangiocarcinoma, hepatocellular carcinoma) had thrombocytopenia in 50% of the cases. The dogs with hepatitis showed no specific changes in the platelet count. The statistical comparison of our patients with liver disease and a control group of healthy dogs showed significantly higher platelet counts in cases of liver degeneration (p < 0.0001) and significantly lower platelet counts in cases of liver tumour (p < 0.001). The comparison between the dogs with different liver diseases showed significantly lower platelet counts in dogs with liver tumours when compared to dogs with liver degeneration (p < 0.0001). There was no significant difference between dogs with liver tumours and dogs with hepatitis and between dogs with liver degeneration and dogs with hepatitis. Based on the results of this study the author recommends to assess platelet counts in all dogs with liver disease, especially if liver biopsy is planed.

Suspected myelodysplastic/myeloproliferative neoplasm in a feline leukemia virus-negative cat.

A 10-year-old castrated Domestic Short-Haired cat was presented to a primary care veterinarian for a wellness examination and laboratory examination for monitoring of diabetes mellitus. The CBC revealed marked thrombocytosis, leukopenia and macrocytic, normochromic anemia. The cat tested negative for FeLV and feline immunodeficiency virus, but was positive for Mycoplasma haemominutum by PCR. Hematologic abnormalities were not responsive to therapy, so a repeat CBC and a bone marrow aspiration for cytology were performed. Additional blood smear findings included anisocytosis with megaloblastic erythroid precursors, large platelets, eosinophilic myelocytes and metamyelocytes, and rare unidentified blasts. The bone marrow smear was highly cellular, and the cytologic pattern was consistent with myelodysplastic syndrome with an erythroid predominance. At that time, 15% blasts were present. The cat was treated with a vitamin K2 analog, doxycycline, and prednisolone, but without a clinical response. Within 3 months, euthanasia was elected due to declining quality of life, and a necropsy was performed. Postmortem bone marrow smears were highly cellular and dominated by monomorphic blasts of unknown line of origin (52%), persistent marked erythroid and megakaryocytic dysplasia, and ineffective erythropoiesis and granulopoiesis. Immunohistochemical, immunocytochemical, and cytochemical stains resulted in a diagnosis of acute myeloid leukemia of unclassified type. Additional histologic findings included mixed hepatitis with trematode infestation and lymphoplasmacytic interstitial nephritis with fibrosis. The marked thrombocytosis with myelodysplastic syndrome and the FeLV-negative status of this cat were unusual. The difficulty in classifying the myelodysplasia and subsequent leukemia highlights a need for further reporting and characterization of these types of disease.

Effect of Haemaphysalis punctata infestation on growing lambs and rabbits.

Lambs infected with adult Haemaphysalis punctata and rabbits infected with nymphs developed a macrocytic normochromic anaemia during seven and six successive infestations, respectively. The anaemia was directly proportional to the degree of infestation but disappeared several days after the termination of infestation. A leucocytosis, due to neutrophilia, was seen in both lambs and rabbits. Rabbits developed a thrombocytosis and reticulocytosis. Infested lambs grew less rapidly than uninfested animals. Signs of tick toxicosis and several other clinical manifestations appeared in both infested sheep and rabbits. Circulating antibodies against salivary antigen of adult H punctata were demonstrated in the sera of infested lambs by the micro-ELISA test. Titres were first detected on day 3 after infestation and increased gradually as infestation progressed. No precipitating antibodies in either infested sheep or rabbits were detected.

Factitious hyperkalemia in dogs with thrombocytosis. The effect of platelets on serum potassium concentration.

To determine the effect of platelet count on the accurate assessment of serum electrolyte concentrations, simultaneous platelet counts and electrolyte determinations were performed on serum and plasma from 40 dogs. Dogs were grouped according to platelet count as follows: thrombocytopenic (less than 150,000/microliters), normal (150,000 to 600,000/microliters), or thrombocytotic (greater than 600,000/microliters). Serum potassium concentration was significantly higher than plasma potassium concentration in normal dogs (mean difference, 0.63 +/- 0.17 mEq/l) and in dogs with thrombocytosis (mean difference, 1.55 +/- 0.73 mEq/l). This difference in potassium concentration between serum and plasma was positively correlated with platelet count (r2 = 0.86). In the blood of dogs with thrombocytosis, the serum-plasma potassium difference was further increased when the time period between blood collection and separation of serum or plasma from cells was lengthened. Differences between serum and plasma concentrations of sodium or chloride were not seen in any platelet group. These results suggest that a portion of the measured serum potassium concentration is released from platelets during the clotting process. In fact, profound elevations in serum potassium concentrations can occur factitiously in dogs with thrombocytosis. Therefore, the actual concentration of potassium in blood is determined more accurately by measuring the plasma concentration rather than the serum concentration of this electrolyte.

Thrombocytosis in 24 horses (1989-1994).

The records of horses presented to the Veterinary Teaching Hospital of North Carolina State University College of Veterinary Medicine between January 1, 1989 and April 30, 1994 were evaluated to determine risk factors associated with thrombocytosis. Of the 2,346 horses for which a CBC was performed, 24 (1.0%) had a platelet count > 400,000/microL. Demographic, diagnostic, physical examination, and clinicopathologic variables from these cases were compared with a reference population consisting of 189 horses with a normal platelet count presenting during the same period. Infectious/ inflammatory disorders were observed more commonly in horses with high platelet counts than in horses with normal platelet counts. Initial independent evaluation of demographic variables revealed that horses more than 3 years of age, females, and geldings were less likely to have thrombocytosis than were younger horses or stallions. Independent analysis of clinicopathologic variables revealed that horses with thrombocytosis were more likely to have hyperfibrinogenemia, leukocytosis, hypoproteinemia, and anemia than were horses with normal platelet counts. Physical examination parameters associated with thrombocytosis included tachycardia and pyrexia. In the final multivariable model, the variables with the strongest association with thrombocytosis included leukocytosis, anemia, and hyperfibrinogenemia. Thrombocytosis rarely causes clinical problems in horses and is not likely to require specific antiplatelet therapy. The strong association of thrombocytosis with infectious/inflammatory disorders, however, should lead clinicians to suspect these types of conditions in horses with high platelet counts.

Basophilic leukemia in a dog.

Basophilic leukemia with thrombocytosis was diagnosed in a 4-year-old Shih Tzu. This diagnosis was based on cytochemical staining and cytologic examination of blood and bone marrow smears. Hydroxyurea, an inhibitor of DNA synthesis, at a dose of 50 mg/kg PO bid induced hematologic remission after 7 days of treatment. Adverse effects observed included pruritus, erythema of the ventral abdomen, generalized alopecia, and possibly, diabetes mellitus. The dog remained in remission for 21 months before becoming lethargic, at which time the owners requested euthanasia but did not allow a necropsy.

Systemic toxicosis associated with azathioprine administration in domestic cats.

Five cats were treated with an azathioprine suspension (2.2 mg/kg of body weight on alternate days) and 2 cats were given vehicle (controls) for 9 weeks. Complete blood and platelet counts and serum biochemistry variables were monitored weekly. Bone marrow aspirates were evaluated every 3 weeks, and core bone marrow biopsy was performed at the end of the study. Profound neutropenia (less than 600 cells/microliters) was observed in all treated cats, and 1 cat developed pancytopenia. Treatment was discontinued if the WBC count was less than 3,000 cells/microliters. Four weeks after discontinuation of azathioprine, 1 treated cat again was given azathioprine at a lower dosage (1.1 mg of azathioprine/kg on alternate days) and neutropenia recurred within 2 weeks. During treatment, 3 cats developed thrombocytosis, and 2 developed thrombocytopenia. In 4 of 5 cats, neutropenia and thrombocytopenia resolved when azathioprine was discontinued. Bone marrow cytologic examination during treatment revealed reduction of the neutrophil line, with relative increase in monocytes. Core bone marrow biopsy at the completion of the study revealed hypocellular marrow with marked decrease in the myeloid series in cats given azathioprine. One of the cats that was treated with azathioprine had a hypercellular marrow with increased numbers of mature granulocytes and precursors; however, azathioprine had been discontinued 3 weeks prior to biopsy. Alterations in serum biochemical variables were not associated with azathioprine. Two cats that were treated with azathioprine developed respiratory tract infections, and 1 of them was euthanatized during the study.

Thrombocytosis associated with a myeloproliferative disorder in a dog.

A dog with a myeloproliferative disorder and thrombocytosis had clinical signs that were consistent with a diagnosis of essential thrombocythemia. The dog was treated with aspirin, radioactive phosphorus, and melphalan. Eighteen months after referral, the disorder progressed to chronic granulocytic leukemia, and treatment was switched to hydroxyurea. Fourteen months later, the dog was euthanatized because of uncontrollable atrial fibrillation.

Treatment of basophilic leukemia in a dog.

Basophilic leukemia in a 6-year-old dog was characterized by marked splenomegaly, anemia, and leukocytosis in which 89% of the circulating leukocytes were basophilis. After an attempt at busulfan therapy, the dog was treated with hydroxyurea and was maintained on this drug for 2 months. After withdrawl of hydroxyurea, the dog remained in remission and was still in remission at the time of writing (8 months later).

Diagnosis of microthrombocytosis and immune-mediated thrombocytopenia in dogs with thrombocytopenia: 68 cases (1987-1989).

The mean platelet volume (MPV) was evaluated in 68 dogs with thrombocytopenia attributable to various causes. Platelet size was high or low in some dogs. The most clinically useful observation was that low MPV (microthrombocytosis) was a specific indicator of immune-mediated thrombocytopenia (IMT) in these thrombocytopenic dogs. All but one case of microthrombocytosis (MPV less than 5.4 fl) was found in dogs with IMT. Microthrombocytosis was detected in 17 of 31 dogs with IMT and appeared at the onset of the disease. Macrothrombocytosis (MPV greater than 9.4 fl) indicated active thrombopoiesis, but was not unique to any disease category. Macrothrombocytosis was detected in 18 of 31 dogs with IMT, 3 of 17 dogs with disseminated intravascular coagulation, and 3 of 9 dogs with primary bone-marrow disease.