Coagulopathy in the equine critical care patient

Disseminated intravascular coagulation (DIC) is a clinicopathologic syndrome resulting from a multitude of underlying causes that manifests itself clinically as hemostatic/fibrinolytic failure. There is much debate on the definition, diagnosis, and treatment of DIC, a situation that is most likely the result of the multifaceted clinical presentation of the syndrome and the fact that patient outcome is often influenced by the underlying disease process. The fact that DIC increases morbidity and mortality in critical care patients is well established, but the exact mechanism of what specifically occurs on a microvascular level is still often argued.

The Incidence of Disseminated Intravascular Coagulation in Dogs with Malignant Tumor

The incidence of DIC in 208 dogs with a malignant tumor was evaluated. The incidence of DIC was 9.6% in dogs with a malignant tumor which was a solid tumor in all. In 164 dogs with a malignant solid tumor, the incidence of DIC was 12.2%. The incidence of DIC in dogs with hemangiosarcoma, mammary gland carcinoma and adenocarcinoma of the lung was significantly higher than that in dogs with other malignant tumors. These results suggested that special care in looking for DIC should be taken in dogs with a malignant solid tumor.

Evaluation of a canine D-dimer point-of-care test kit for use in samples obtained from dogs with disseminated intravascular coagulation, thromboembolic disease, and hemorrhage

OBJECTIVE

To evaluate a canine D-dimer point-of-care (cD-d POC) test kit for use in healthy dogs and dogs with disseminated intravascular coagulation (DIC), thromboembolic disease (TED), and hemorrhage.

ANIMALS

12 healthy dogs, 18 dogs with DIC, 23 dogs with TED (19 acute and 4 chronic), and 18 dogs with hemorrhage.

PROCEDURE

The cD-d POC, canine D-dimer ELISA (cD-d ELISA), human D-dimer latex agglutination (hD-d LA), and fibrin degradation product (FDP) tests were performed on citrated plasma.

RESULTS

All healthy dogs had negative cD-d POC test results and mean cD-d ELISA value of 0.2 U/mL. All dogs with DIC had positive cD-d POC test results and mean cD-d ELISA value of 44 U/mL. Dogs with acuteTED had a mean cD-d ELISA value of 34 U/mL, and 17 of 19 had positive cD-d POC test results. Mean cD-d ELISA value in dogs with hemorrhage was 14 units/mL, and 15 of 18 had positive cD-d POC test results. The cD-d ELISA values in dogs with hemorrhage were significantly higher than those of healthy dogs but lower than those of dogs with DIC and acute TED. The cD-d POC, cD-d ELISA, and hD-d LA tests were comparable in differentiating healthy dogs from dogs with DIC, acute TED, or hemorrhage and appeared to be superior to measurement of FDPs.

CONCLUSIONS AND CLINICAL RELEVANCE

The cD-d POC test kit can be quickly and easily used and reliably detects dogs with DIC or acute TED. Positive results may also be seen in dogs with internal hemorrhage.

Plasma D-dimer for the diagnosis of thromboembolic disorders in dogs

D-dimer is formed during thrombus formation when factor XIIIa crosslinks the terminal D-domains of fibrin. The D-dimer epitope is exposed when the thrombus is lysed by plasmin. Thus, D-dimer represents both thrombin and plasmin activation and is specific for fibrinolysis. D-dimer concentrations are increased in dogs with DIC or other thromboembolic disorders, but because D-dimer is an indicator of physiologic or pathologic fibrinolysis, values are elevated in other conditions associated with fibrinolysis, including orthopedic surgery, neoplasia, and internal hemorrhage. It can be used as an ancillary test for the diagnosis of DIC but is not recommended as a sole test for this purpose. D-dimer has the potential to be a useful laboratory test for the detection of pulmonary thromboembolism in dogs. Further studies are needed to determine the appropriate applications for this test in veterinary patients to aid in clinical decision making, treatment, and patient care.

The Utility of Plasma D-dimer to Identify Thromboembolic Disease in Dogs

This prospective study was designed to investigate D-dimer concentrations in clinically healthy dogs, clinically ill dogs without thromboembolic disease (TE), and dogs with TE. The goals of this study were to determine whether the coagulation cascade is activated in nonembolic metabolic and inflammatory conditions and whether differentiation from TE is possible. Group 1 consisted of 30 clinically healthy dogs presented for routine care. Group 2 consisted of 67 clinically ill dogs without TE. This group was subdivided into the following categories: postoperative surgical procedures, congestive heart failure, renal failure, hepatic disease, and neoplastic disease. Group 3 consisted of 20 dogs diagnosed with TE. A CBC and a measurement of prothrombin time (PT), activated partial thromboplastin time (PTT), fibrinogen degradation product (FDP) concentration, and plasma D-dimer concentration was performed on dogs in all groups. D-dimer concentrations were highest in dogs with TE; next highest was the hepatic disease group. Only these 2 groups had median D-dimer concentrations markedly different from clinically healthy dogs. The frequency of platelet abnormalities was markedly greater for the TE and neoplastic disease groups. The sensitivity of D-dimer concentrations >500 ng/mL for predicting TE was 100%; however, the specificity of D-dimer for TE at that concentration was 70%. The specificity of D-dimer concentrations >1,000 ng/mL to predict TE was 94% (sensitivity, 80%), and the specificity of D-dimer concentrations >2,000 ng/mL was 98.5% (sensitivity, 36%). FDPs were not high in any TE patient; thus, they may be an insensitive indicator of thromboembolism, with or without overt disseminated intravascular coagulation (DIC).

Changes in coagulation and markers of fibrinolysis in horses undergoing colic surgery

Activation of coagulation can be frequently found in horses with colic. However, it has also been demonstrated as a sequela of surgical trauma alone in humans. The purpose of the present study was to determine changes in coagulation and fibrinolysis in horses that underwent colic surgery and to evaluate whether these changes were secondary to the colic or the surgery and wound healing. Thirty horses that underwent colic surgery with uncomplicated recovery were included. Ten horses with a Forssell's procedure served as control group with a standardized surgical trauma. Besides daily physical examinations during the observation period of 10 days, activated partial thromboplastin time (aPTT), prothrombin time and thrombin time as well as fibrin monomer (FM), D-Dimer (DD) and antithrombin (AT) III were determined. Compared with the control group the aPTT was the only standard coagulation test that was significantly prolonged before and after the event of colic surgery. After surgery, hyperfibrinogenaemia occurred in all groups. In colic groups FM and DD concentrations were within reference range at admission,and were significantly greater than in control horses after surgery. AT III activity decreased after colic surgery, but did not change in the control group. It was concluded that an activated coagulation state after colic surgery has to be expected, resulting not only from the colic disease, but also from the event of surgery.

Prognostic factors for mortality and thromboembolism in canine immune-mediated hemolytic anemia: a retrospective study of 72 dogs

Medical records of 72 dogs diagnosed with immune-mediated hemolytic anemia (IMHA) were reviewed to find risk factors for the disease, for mortality, and for thromboembolism. Coagulation data of 32 patients were evaluated for mortality or thromboembolism risk factors. Cocker Spaniels were at increased risk for IMHA (P = .012). Timing of vaccination was not associated with development of IMHA. PCV ranged from 5 to 33%, with a mean of 16 +/- 5%. Autoagglutination was present in 42% of the dogs. Platelet counts (n = 60) varied from 3,000 to 793,000/microL (mean, 160,117 +/- 133,571; median, 144,000). Thrombocytopenia (platelet count, <200,000/microL) was present in 70% of the dogs, with severe thrombocytopenia (platelet count, <50,000/microL) being present in 22%. One-step prothrombin time (OSPT) was prolonged in 28% of the dogs tested, and activated partial thromboplastin time (APTT) was prolonged in 47% of the dogs tested. Fibrin(ogen) degradation products (FDPs) were detected in 16 of 28 dogs tested (57%). Disseminated intravascular coagulation (DIC) was diagnosed in 10 of 31 (32%) dogs and was suspected in 8 dogs. Thromboemboli were found in 20 of 25 dogs given postmortem examinations. Mortality rate was 58%. Thrombocytopenia (P = .008) and serum bilirubin concentration of >5 mg/dL (P = .015) were risk factors for mortality, and hypoalbuminemia approached significance (P = .053). Severe thrombocytopenia (P = .046), serum bilirubin concentration of >5 mg/dL (P = .038), and hypoalbuminemia (P = .016) were risk factors for thromboembolism. On evaluation of continuous data, decreased platelet count (P = .057), increased bilirubin (P = .062), and decreased albumin (P = .054) approached significance for decreased survival. A higher risk for thrombosis was found with increased alkaline phosphatase (ALKP) (P = .042), increased bilirubin (P = .047), and decreased albumin (P = .012).

Clinicopathologic evidence of disseminated intravascular coagulation in horses with acute colitis

OBJECTIVE

To detect subclinical disseminated intravascular coagulation (DIC) in horses with colitis and to determine any association between the diagnosis of subclinical DIC and outcome or occurrence of complications in horses with colitis.

DESIGN

Prospective study.

ANIMALS

37 horses admitted to a veterinary teaching hospital for treatment of acute colitis.

PROCEDURE

Coagulation profiles were obtained on each horse 0, 24, and 48 hours after admission. Six tests were performed: platelet count, plasma fibrinogen concentration, prothrombin time, activated partial thromboplastin time, antithrombin activity, and serum fibrin degradation products concentration.

RESULTS

A clinicopathologic diagnosis of subclinical DIC was made if 3 of the 6 tests had abnormal results at any 1 sample period. No horse had clinical signs of DIC at the time of sampling. Twelve of 37 (32%) horses met the criteria for diagnosis of subclinical DIC within a 1-year period. Outcome was defined as survival or nonsurvival. Five of 12 horses with subclinical DIC and 2 of 25 horses without subclinical DIC did not survive. Crude odds ratio analysis revealed a horse with acute colitis was 8 times as likely to die or be euthanatized if a diagnosis of subclinical DIC was made.

CONCLUSIONS AND CLINICAL RELEVANCE

Clinicopathologic evidence of DIC is common and is significantly associated with a poor outcome in horses with acute colitis. Treatment of subclinical DIC may influence outcome in horses with acute colitis.

Hypercoagulation and hypofibrinolysis in horses with colic and DIC

Changes in haemostasis in horses with colic were assessed by using specific and sensitive markers of coagulation and fibrinolysis activity. Blood samples from 41 horses with severe colic and from 30 healthy control horses were tested. Diagnosis of DIC was based on the findings of at least 3 of 6 abnormalities: thrombocytopenia, prolonged clotting times (PT and APTT), increased polyclonal FDPs, decreased fibrinogen and decreased AT-III activity. Plasma thrombin-antithrombin III complexes (TAT), monoclonal fibrin degradation products fragment D (D-dimer) and monoclonal fibrinogen degradation products (FgDP) were also tested by using ELISA kits. DIC was diagnosed in 16 of 41 horses with colic. Compared to control and non-DIC colic values, TAT was significantly (P < 0.000) greater in horses with colic and DIC (Control group, mean +/- s.d. 2.6 +/- 2; non-DIC colic group, 7.5 +/- 9, and DIC colic group, 30.9 +/- 36 ng/ml). Also, D-dimer was significantly (P < 0.000) less in the DIC group when compared to control and non-DIC colic values (mean +/- s.d. 677 +/- 119, 682 +/- 220 and 399 +/- 234 ng/ml, respectively). Compared to non-DIC colic values, FgDP was significantly (P < 0.05) lower in the DIC group (363 +/- 111, 437 +/- 230 and 293 +/- 187 ng/ml respectively). Both PT and APTT showed a significant positive correlation with TAT. DIC was more common among nonsurvivors and horses with ischaemic bowel. We conclude that a hypercoagulative state was detected in horses with colic, which was stronger in horses with colic and DIC. Hypofibrinolysis was present only in horses with DIC. Therefore, marked hypercoagulation together with hypofibrinolysis are associated with DIC in horses.

D-dimer concentrations in healthy dogs and dogs with disseminated intravascular coagulation

OBJECTIVE

To determine sensitivity and specificity of assays of D-dimer concentrations in dogs with disseminated intravascular coagulation (DIC) and healthy dogs and to compare these results with those of serum and plasma fibrin-fibrinogen degradation product (FDP) assays.

ANIMALS

20 dogs with DIC and 30 healthy dogs.

PROCEDURE

Semi-quantitative and quantitative D-dimer concentrations were determined by use of latex-agglutination and immunoturbidometry, respectively. Fibrin-fibrinogen degradation products were measured by use of latex-agglutination. A reference range for the immunoturbidometric D-dimer concentration assay was established; sensitivity and specificity of the assay were determined at 2 cutoff concentrations (0.30 microg/ml and 0.39 microg/ml).

RESULTS

Reference range for the immunoturbidometric D-dimer concentration assay was 0.08 to 0.39 microg/ml; median concentrations were significantly higher in dogs with DIC than in healthy dogs. Latex-agglutination D-dimer and serum and plasma FDP assays had similar sensitivity (85 to 100%) and specificity (90 to 100%); the immunoturbidometric assay had lower specificity (77%) at the 0.30 microg/ml cutoff and lower sensitivity (65%) at the 0.39 microg/ml cutoff. Sensitivity or specificity of the latex-agglutination D-dimer assay was not significantly improved when interpreted in series or parallel with FDP assays.

CONCLUSIONS AND CLINICAL RELEVANCE

Measurement of D-dimer concentrations by latex-agglutination appears to be a sensitive and specific ancillary test for DIC in dogs. Specificity of D-dimer concentrations in dogs with systemic disease other than DIC has not been determined, therefore FDP and D-dimer assays should be performed concurrently as supportive tests for the diagnosis of DIC in dogs.

Thrombosis of the caudal vena cava presenting as an unusual cause of an abdominal mass and thrombocytopenia in a dog

Thrombosis of the caudal vena cava in a dog secondary to metastatic neoplasia is described. The dog had a palpable abdominal mass and persistent thrombocytopenia due to a thrombosed caudal vena cava that was surgically removed. A few days after its removal, the dog died and neoplastic cells of neural crest origin were identified at the edge of the thrombus. Massive thrombosis can be an unusual cause of platelet consumption, leading to thrombocytopenia and disseminated intravascular coagulation. Deep vein thrombosis of the vena cava can occur in dogs and may mimic an abdominal mass. Multiple mechanisms may be involved in the development of venous thrombosis, including endothelial damage by neoplastic cells and the presence of a hypercoagulable state secondary to neoplasia. Extensive collateral circulation may allow removal of diseased vena cava.

Evaluation of point-of-care tests for diagnosis of disseminated intravascular coagulation in dogs admitted to an intensive care unit

OBJECTIVE

To evaluate the accuracy of point-of-care tests for the diagnosis of disseminated intravascular coagulation (DIC) in dogs and assess the correlation and agreement of results between point-of-care and laboratory tests in the evaluation of hemostatic function.

DESIGN

Prospective case series.

ANIMALS

59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs.

PROCEDURES

Accuracy of the point-of-care tests (activated clotting time [ACT], estimated platelet count and number of schizocytes from a blood smear, plasma total solids [TS] concentration, and the protamine sulfate test) was evaluated, using receiver operating characteristic curves and likelihood ratios. A strategy, using likelihood ratios to calculate a posttest probability of DIC, was tested with 65% used as a threshold for initiation of treatment. Results of laboratory tests (coagulogram and plasma antithrombin III activity) were used as the standard for comparison in each dog.

RESULTS

ACT and estimated platelet count provided the best accuracy for detection of DIC. The plasma TS concentration, schizocyte number, and protamine sulfate test had poor accuracy. The strategy using post-test probability of DIC identified 12 of 16 affected dogs that had DIC. Estimated platelet count was correlated and had acceptable clinical agreement with automated platelet count (r = 0.70). The plasma TS (r = 0.28) concentration and serum albumin (r = 0.63) concentration were not accurate predictors of plasma antithrombin III activity. The ACT did not correlate with activated partial thromboplastin time (r = 0.28).

CONCLUSIONS AND CLINICAL RELEVANCE

Strategic use of likelihood ratios from point-of-care tests can assist clinicians in making treatment decisions for dogs suspected to have DIC when immediate laboratory support is unavailable.

Diagnosis of disseminated intravascular coagulation in dogs admitted to an intensive care unit

OBJECTIVE

To describe and evaluate hemostatic function in critically ill dogs with clinical signs of diseases that predispose to disseminated intravascular coagulation (DIC).

DESIGN

Prospective case series.

ANIMALS

59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs (control dogs).

PROCEDURE

Activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin clotting time (TCT), plasma fibrinogen concentration, serum concentration of fibrin and fibrinogen-related antigens (FRA), and plasma antithrombin III (AT III) activity were determined for all dogs. Results from affected dogs were compared with those of control dogs. In some affected dogs, postmortem tissue specimens were examined for evidence of microvascular thrombosis. A diagnosis of DIC was made by fulfilling at least 3 of the following criteria: 1) abnormal aPTT, PT, or TCT value, 2) low plasma fibrinogen concentration, 3) low plasma AT III activity, 4) high serum FRA concentration, or 5) low platelet count. To evaluate the severity of hemostatic dysfunction, 3 arbitrary categories (mild, moderate, and severe) were proposed.

RESULTS

A diagnostic strategy based on moderate hemostatic dysfunction identified DIC in 16 of 59 (27.1%) affected dogs. The AT III activity was < 70% in 15 of 16 dogs with DIC. Microvascular thrombosis was observed in tissue specimens from 7 of 8 affected dogs. Serum FRA and plasma fibrinogen concentrations did not contribute in establishing a diagnosis of DIC.

CONCLUSIONS AND CLINICAL RELEVANCE

A diagnosis of DIC can be made when hemostatic dysfunction is moderate in dogs with clinical signs of diseases associated with DIC.

Evaluation of kits for the detection of fibrin(ogen) degradation products in dogs

The sensitivities and specificities of 3 commercial serum fibrin(ogen) degradation product (FDP) kits and 1 plasma FDP kit for the detection of FDPs in dogs were determined. Blood was collected for measurement of serum and plasma FDP concentrations from 30 healthy dogs and from 20 dogs that fulfilled clinical and laboratory criteria for disseminated intravascular coagulation. To determine the effect of hemolysis on FDP results, blood was collected simultaneously into Bothrops atrox venom-based and thrombin-based serum collection tubes for measurement of FDPs using a single serum FDP kit. The sensitivity (80-95%) and specificity (90-100%) for a positive or negative FDP result, regardless of concentration, was similar for all kits. Kits yielded discordant results in individual dogs and FDP concentrations obtained from 1 serum FDP kit were consistently higher than those from the other kits. Serum prepared from venom-based collection tubes was significantly more hemolyzed than serum prepared from thrombin-based collection tubes or citrated plasma. Hemolysis did not affect the FDP results. On the basis of these results, we conclude that commercial latex agglutination kits for detection of FDPs in serum and plasma samples from human patients are valid for use in dogs. The plasma FDP assay is a viable alternative to currently used serum FDP assays and has the advantage of using a single (citrated plasma) sample for measuring coagulation parameters and FDP concentration.

Hypercalcemia and parathyroid hormone-related protein in a dog with undifferentiated nasal carcinoma

Hypercalcemia was discovered in a 7-year-old, castrated male basset hound with a suspected nasal tumor. The dog died the day after admission and nasal carcinoma and disseminated intravascular coagulation were diagnosed on postmortem. Detectable levels of serum PTHrP support a diagnosis of hypercalcemia of malignancy.

Unusual metastatic behavior and clinicopathologic findings in eight cats with cutaneous or visceral hemangiosarcoma

Eight cats with visceral or cutaneous hemangiosarcoma were evaluated, and unusual metastatic and clinicopathologic behavior was evident in each. Cutaneous hemangiosarcoma is generally believed to be locally aggressive and slow to metastasize. These 8 cats with cutaneous hemangiosarcoma, however, developed metastatic disease after initial surgical resection; only 1 had local regrowth of the tumor. All cats with visceral hemangiosarcoma had metastasis at the time of diagnosis, which is consistent with cats of other reports. Three of 8 cats had evidence of disseminated intravascular coagulation, including increased prothrombin time and partial thromboplastin time, decreased number of platelets, and anemia. These potential complications need to be considered when planning diagnostic and treatment protocols.

[Disseminated intravascular coagulation and hyperfibrinolysis in dogs with metastasizing mammary carcinoma]

The alterations of the haemostatic system (platelet count, activated partial thromboplastin time [APTT], thromboplastin time [standard test, modified test], thrombin time, fibrinogen concentration, activity of the coagulation factors II, V, VII, X, VIII:C, IX, XI, XII, of prekallikrein, high molecular weight kininogen, antithrombin III, protein C, plasminogen and alpha 2-plasmin inhibitor, concentration of soluble fibrin and fibrin(ogen) degradation products [FDP], resonance thrombogram) were described in seven dogs with haemorrhagic diathesis in consequence of an infiltrative, growing mammary carcinoma with multifocal invasion of lymphatic and blood vessels. In most of the cases metastases in different organs could be demonstrated. In every case a serious stage of disseminated intravascular coagulation and hyperfibrinolysis was existent. This was indicated by the distinctly increased concentration (p < 0.0001) of soluble fibrin (27.7 [16.0-79.2] micrograms/ml, median [minimum-maximum], reference range [RR.]: < 9.4 micrograms/ml) and FDP (340 [50-860] micrograms/ml, RR.: < 18 micrograms/ml) as well as a diminished plasma level of nearly all components of the coagulation and fibrinolytic system concerning especially the concentration of fibrinogen (0.16 [0.01-0.46] g/l, RR.: 1.17-3.09 g/l), the activity of factors V (30 [21-40]%, RR.: 75-158%) and VIII:C (9 [4-16]%, RR.: 72-136%) as well as the activity of protein C (8 [3-13]%, RR.: 68-139%) (each: p < 0.0001).

The sepsis-coagulant axis: a review

Activation of coagulation is a normal component of the acute inflammatory response. Inflammatory cytokines initiate coagulation events locally at sites of inflammation by converting endothelium from an antithrombotic surface to a prothrombotic surface; by stimulating tissue factor production, which activates both the extrinsic and intrinsic coagulation systems; and by stimulating production of platelet-activating factors. The fibrinolytic system is initially activated but is subsequently inhibited. This results in a marked imbalance in coagulation and fibrinolysis resulting in a net procoagulant state. When thrombin generation and platelet activation exceed the body's capacity to inactivate or remove these factors, disseminated intravascular coagulation (DIC) results. DIC directly contributes to multiple organ failure and death associated with sepsis. Presently available treatments (i.e., heparin and aspirin) are relatively ineffective in treating DIC; however, newer, more potent drugs may soon be available for clinical use.

Haemophagocytic syndrome with disseminated intravascular coagulation in a dog

Clinical signs and haematological abnormalities of haemophagocytic syndrome of unknown origin are described for a male, nine-year-old rottweiler referred because of weakness, depression, mild weight loss and relapsing fever. Mucous membranes were pale and the spleen was enlarged. Ultrasonography revealed diffuse irregular structures in the enlarged spleen, and cytological examination of multiple fine needle aspirates of the spleen demonstrated extramedullary haematopoiesis. Haematological examination revealed pancytopenia and disseminated intravascular coagulation. A bone marrow smear contained numerous marrow macrophages with a cytologically benign appearance, containing phagocytosed haematopoietic cells. The dog died one week after referral. The differential diagnosis is discussed.

Nephrotic syndrome resulting in thromboembolic disease and disseminated intravascular coagulation in a dog

Thromboembolic disease and progression to disseminated intravascular coagulation (DIC) are potential life-threatening complications for dogs with nephrotic syndrome. Platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), plasma concentration of fibrinogen degradation products (FDPs), antithrombin III (ATIII), protein C, and plasminogen were used to identify hemostatic abnormalities in a dog with nephrotic syndrome. Pulmonary thromboembolic disease was diagnosed by thoracic radiography, arterial blood gas analysis, and pulmonary scintigraphy. Prompt recognition and treatment of hemostatic complications is necessary in dogs with nephrotic syndrome.

Disseminated intravascular coagulation in chickens inoculated with Erysipelothrix rhusiopathiae

In a first experiment, 28 specific pathogen-free chickens aged 3 weeks showed clinical signs 1 to 5 days after intramuscular inoculation with Erysipelothrix rhusiopathiae. Twelve of 28 birds died 2 to 4 days after inoculation. Macroscopically, the liver, spleen and kidneys were seen to be enlarged and congested. Histologically, fibrinous thrombus formation, seen in the hepatic sinusoids, renal glomerular capillaries and small pulmonary blood vessels, was a characteristic feature. In addition, the liver showed marked congestion, increase of mononuclear cells and heterophils in the sinusoids, hyperplasia of sinusoidal lining cells, and vacuolar changes in hepatic cells. The spleen showed fibrinous exudation of the lymphoid follicles and ellipsoids with lymphocytic depletion, and hyperplasia of ellipsoidal reticular cells. There was oedema, congestion and cellular infiltration in the interstitium of the kidney. The bursa of Fabricius and thymus showed marked lymphocytic depletion. In a second experiment, the blood chemical values (uric acid, glutamic-oxalacetic transaminase, lactate dehydrogenase and gamma-glutamyl transpeptidase) of birds inoculated intramuscularly with E. rhusiopathiae were significantly higher than those of uninfected controls. The blood prothrombin times and activated partial thromboplastin times of the inoculated group were significantly greater than those of the control group. The pathological and haematological findings demonstrated that E. rhusiopathiae induced disseminated intravascular coagulation in the chickens.