Platelet Dysfunction Associated With Immune-Mediated Thrombocytopenia in Dogs

The effect of antiplatelet antibody on in vitro platelet function was investigated in 15 dogs with immune-mediated thrombocytopenia (ITP). Platelet aggregation was assessed after addition of serum from healthy dogs (n = 5) or dogs with ITP (n = 15) to platelet-rich plasma from a healthy donor dog. The aggregation responses to adenosine diphosphate, thrombin, and collagen/epinephrine were measured as the maximum aggregation observed after 2 minutes. In 13 of 15 dogs with ITP, maximal aggregation was significantly inhibited in response to ADP, thrombin, or collagen/epinephrine. The slope of the aggregation curve was decreased after addition of serum from 9 of 15 patients. A polyclonal rabbit anti—dog platelet antiserum induced inhibition of aggregation with all 3 agonists.
Serum from control dogs neither inhibited nor activated platelet aggregation. Aggregation experiments were repeated with all 3 agonists after addition of patient immunoglobulin (lg)G or IgG from a healthy dog to platelet-rich plasma. The IgG fraction from 9 of 10 dogs with ITP suppressed platelet aggregation. The IgG fraction from polyclonal rabbit anti—dog platelet antiserum inhibited platelet aggregation with all agonists. These results suggest that many canine ITP patients have circulating antibodies that, in addition to causing platelet destruction, may cause platelet dysfunction.     

Osteomyelitis Associated With Disseminated Blastomycosis in Nine Dogs

Blastomycosis, a common disease entity of dogs in the southeastern United States, may be encountered elsewhere. Blastomyces dermatitidis, the cause of this disease, is a soil-borne fungal organism. B. dermatitidis is introduced into the host by inhalation of infective spores. This results in a primary lung infection. Dissemination of the organism occurs by lymphohematogenous means and may involve any body tissue. Other tissues frequently involved are the skin, male genitals, lymph nodes, eyes, and bone. Osteomyelitis was diagnosed in nine dogs with disseminated blastomycosis. Six of nine dogs had solitary bone lesions. All nine dogs had a clinical lameness. Only two dogs had clinical signs of respiratory disease. A total of 25 bone lesions were observed in these dogs, with 19 lesions located in the tubular bones of the extremities. Typically, osteolytic lesions appeared at the ends of long bones; only two lesions were observed proximal to the stifle. No extremity lesions were seen proximal to the elbow. Approximately half of the bone lesions had an associated periosteal response or soft tissue enlargement, while no sinus or fistulous tracts were observed. Blastomycosis was confirmed in all dogs by a positive reaction to the gel immunodiffusion test and/or identification of the B. dermatitidis organism. 0rganisms were retrieved and identified from a variety of tissues, including three bone biopsy specimens and one joint aspirate. In seven of nine dogs, initial diagnosis was by identification of the organism. The radiographic differential diagnoses included primary bone neoplasia, soft tissue neoplasia with secondary bone involvement, fungal osteomyelitis, and bacterial osteomyelitis. These differential diagnoses were based on the distribution, localization, and aggressiveness of the lesions observed. The 32 percent incidence of blastomycosis-associated osteomyelitis reported here is significantly higher than reported previously.     

Thrombocytopenia Associated With Acute Bovine Virus Diarrhea Infection in Cattle

Thrombocytopenia was observed in 15 of 146 cases of clinically acute bovine viral diarrhea virus (BVDV) infection in adult cattle. Platelet counts ranged from 2,000 to 33,000/microliters. Clinically, a bleeding tendency was manifested by bloody diarrhea, petechial and ecchymotic hemorrhage, epistaxis, and abnormal bleeding from injection sites. Coagulation testing (six cases) gave no evidence of disseminated intravascular coagulation. Bone marrow aspirates were suggestive of active marrow necrosis (two cases) or recent repopulation (three cases). Treatment, when given, was supportive and empirical in nature. Six animals experienced complete clinical recoveries; the others died or were euthanatized. Although the pathogenesis of the thrombocytopenia was not definitively determined, thrombocytopenia associated with acute BVDV infection should be considered in the differential diagnosis for cattle with bleeding disorders.     

Cholestasis Associated With Extrahepatic Bacterial Infection in Five Dogs

Intrahepatic cholestasis associated with severe extrahepatic bacterial infection is well recognized in humans. A similar syndrome is not well characterized in veterinary medicine. Five dogs with severe extrahepatic bacterial infection that developed histologically confirmed intrahepatic cholestasis were selected from the authors' case files. The types of infections included pneumonia, peritonitis secondary to a rectal tear, urinary tract infection, bite wounds, and vegetative endocarditis. Escherichia coli was involved in two of the dogs, mixed infection in one dog, and a gram-positive cocci in the other two dogs. Total bilirubin concentrations ranged from 3.5 to 33.5 mg/dl. Serum liver enzyme activities showed only mild to moderate increases: alkaline phosphatase (ALP, 41-750 IU/l), alanine aminotransferase (ALT, 25-235 IU/l), and aspartate aminotransferase (AST, 99-255 IU/l). Fasting serum bile acids concentration was markedly elevated in the one dog in which it was measured (259 mumol/l). Histologically, the cholestasis was characterized by bile pigment accumulation in hepatocytes, canaliculi, and/or Kupffer's cells. Inflammatory parenchymal changes, when present, were minimal. The findings of hyperbilirubinemia, only a slight increase in the liver enzyme activities, and minimal inflammatory changes in liver tissue specimens in the five dogs with extrahepatic bacterial infections are similar to the findings in intrahepatic cholestasis associated with extrahepatic bacterial infection in humans.     

Hepatic Abscesses Associated With Diabetes Mellitus in Two Dogs

Two diabetic dogs were presented for anorexia, persistent fever, and poor control of hyperglycemia. Both had neutrophilia with left shift, hypoalbuminemia, and increased serum alkaline phosphatase (SAP) activity. Radiography indicated intrahepatic gas densities in 1 dog and a hepatic mass in the other. Abdominal sonography demonstrated multiple well-demarcated hypoechoic hepatic lesions consistent with abscesses. Both dogs were successfully treated by surgical resection of the abscessed liver lobes inconjunction with antibiotics and supportive therapy. Good control of hyperglycemia was achieved in both dogs after recovery. Intracellular and extracellular Gram-negative rod-shaped bacteria were abundant in the abscesses from both dogs. These cases suggest an association between diabetes mellitus and hepatic abscessation.     

Hematologic Changes Associated With Serum and Hepatic Iron Alterations in Dogs With Congenital Portosystemic Vascular Anomalies

Serum and hepatic iron determinations and hematologic parameters were measured in 10 dogs with congenital portosystemic vascular anomalies. Anemia, hypoferremia, and microcytosis were present in 70%, 70%, and 60% of the dogs, respectively. An increase in hepatic iron content was observed in all dogs. These results suggest a relationship between altered hepatic blood flow and abnormal iron metabolism in dogs with congenital portosystemic vascular anomalies.     

Artifactual Prolongation of the Activated Partial Thromboplastin Time Associated With Hemoconcentration in Dogs

An inappropriate blood-to-anticoagulant ratio can cause an artifactual prolongation of the activated partial thromboplastin time (APTT) and prothrombin time (PT). In a drug safety study in dogs, we observed a 4-to 5-second increase in the APTT from baseline coincident with increased hematocrit values (56% to 65%) secondary to drug-induced vomiting and diarrhea. The PT and platelet counts were unchanged, and there was no clinical evidence of bleeding associated with venipuncture. Although we were unable to sample the same dogs to investigate the possible effect of hemoconcentration on the prolonged APTT, the question was addressed by an in vitro study. The hematocrit value for citrated blood samples collected from healthy beagle dogs was increased by the addition of aliquots of red blood cell/plasma mixtures in vitro while maintaining a 9:1 blood-to-anticoagulant ratio. There was a 2-to 4-second prolongation of the APTT associated with hematocrit values of 55% to 61 %, but the PT was not prolonged. Adjustment of the blood-to-anticoagulant ratio corrected the prolongation. This study emphasizes the important relationship of the blood-to-anticoagulant ratio when measuring coagulation tests in hemoconcentrated samples.     

26例犬免疫介导性血小板减少症回顾性分析

旨在调查犬免疫介导性血小板减少症(immune thrombocytopenia,ITP)的发病和治疗情况,并探讨预后相关因素。本研究自2018―2019年于中国农业大学动物医院接诊的病例中筛选出26例符合要求的ITP病例,记录患犬的基本信息、临床表现、实验室检查结果以及治疗和预后情况,并进行统计学分析。结果显示,贵宾犬为主要的发病品种(58%);伊文氏综合征(Evans syndrome)与诊断后短期内(14 d)死亡显著相关(P=0.02);初诊时,所有患犬皆具有出血的临床表现,根据一种新型犬ITP出血评估工具(DOGiBAT)所得出的评分范围为3~10分,其中,评分>5的患犬与诊断后短期内死亡显著相关(P=0.03),提示出血评分对判断疾病转归有一定的指导意义。此外,出血评分>5的犬C反应蛋白(C-reactive protein, CRP)检测结果显著高于出血评分≤5的犬(P=0.01),初步提示CRP具有辅助判断ITP严重程度的意义。本研究建议在评估ITP预后时引入出血评分工具,相比单一的临床表现更能量化疾病的严重程度,并提供可靠的预后判断。     

Central Nervous System Infection Associated With Anaerobic Bacteria in Two Dogs and Two Cats

Central nervous system (CNS) infection caused by anaerobic bacteria (including Bacteroides, Fusobacterium, Peptostreptococcus, and Eubacterium) was diagnosed in two dogs and two cats. In one dog there was extensive meningomyeloencephalitis, presumably the result of hematogenous spread of bacteria from lung abscesses and bacterial endocarditis. Subdural empyema of unknown origin was found in a second dog and two cats. Clinical signs in all four animals included mental depression and focal neurologic deficits, without fever.     

Aggression in Dogs and Associated Neuropathology

The central nervous systems of eight dogs with behavioral changes were compared. Three had pathological lesions involving the limbic system. The nervous system and, in particular, the limbic system should be examined as a possible site for lesions in dogs with a history of behavioral changes.     

Clinical Tolerance and Bronchoscopic Changes Associated With Transtracheal High-Frequency jet Ventilation in Dogs and Cats

Eleven awake dogs and two cats received high-frequency jet ventilation (HFJV) via a transtracheal catheter for 6 hours to evaluate their clinical tolerance to the technique. A bronchoscopic examination was performed in all animals prior to and the morning of the day after the procedure to determine the gross effects of the technique on the tracheal epithelium.
All animals tolerated the technique well, exhibiting no discomfort and only a minimal amount of coughing. Only one dog exhibited coughing on the day following the procedure. No bronchoscopic changes were noted after HFJV in one dog. In one dog and one cat, the only observed change was an increase in the prominence of the vascularity compared to that observed prior to HFJV. The remaining animals exhibited more severe tracheal changes that included: an accumulation of mucus (seven dogs, one cat), focal spots of hemorrhage (two dogs), linear stretches of epithelial denuding (two dogs), and diffuse reddening and epithelial denuding (four dogs).
High-frequency jet ventilation by a transtracheal intravenous catheter is well tolerated for short-term ventilatory support in dogs and cats, but the magnitude of the tracheal damage observed in the present report may preclude long-term ventilatory support by this tecnique.     

Basal and Glucagon-Stimulated Plasma C-PeDtide Concentrations in Healthy Dogs, Dogs With Diabetes Millitus, and Dogs With Hyperadrenocorticism

Serum glucose and plasma C-peptide response to IV glucagon administration was evaluated in 24 healthy dogs, 12 dogs with untreated diabetes mellitus, 30 dogs with insulin-treated diabetes mellitus, and 8 dogs with naturally acquired hyperadrenocorticism. Serum insulin response also was evaluated in all dogs, except 20 insulin-treated diabetic dogs. Blood samples for serum glucose, serum insulin, and plasma C-peptide determinations were collected immediately before and 5,10,20,30, and (for healthy dogs) 60 minutes after IV administration of 1 mg glucagon per dog. In healthy dogs, the patterns of glucagon-stimulated changes in plasma C-peptide and serum insulin concentrations were identical, with single peaks in plasma C-peptide and serum insulin concentrations observed approximately 15 minutes after IV glucagon administration. Mean plasma C-peptide and serum insulin concentrations in untreated diabetic dogs, and mean plasma C-peptide concentration in insulin-treated diabetic dogs did not increase significantly after IV glucagon administration. The validity of serum insulin concentration results was questionable in 10 insulin-treated diabetic dogs, possibly because of anti-insulin antibody interference with the insulin radioimmunoassay. Plasma C-peptide and serum insulin concentrations were significantly increased (P < .001) at all blood sarnplkg times after glucagon administration in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Five-minute C-peptide increment, C-peptide peak response, total C-peptide secretion, and, for untreated diabetic dogs, insulin peak response and total insulin secretion were significantly lower (P < .001) in diabetic dogs, compared with healthy dogs, whereas these same parameters were significantly increased (P < .011 in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Although not statistically significant, there was a trend for higher plasma C-peptide concentrations in untreated diabetic dogs compared with insulin-treated diabetic dogs during the glucagon stimulation test. Baseline C-peptide concentrations also were significantly higher (P < .05) in diabetic dogs treated with insulin for less than 6 months, compared with diabetic dogs treated for longer than 1 year. Finally, 7 of 42 diabetic dogs had baseline plasma C-peptide concentrations greater than 2 SD (ie, >0.29 pmol/mL) above the normal mean plasma C-peptide concentration; values that were significantly higher, compared with results in healthy dogs (P < .001) and with the other 35 diabetic dogs (P < .001). In summary, measurement of plasma C-peptide concentration during glucagon stimulation testing allowed differentiation among healthy dogs, dogs with impaired β-cell function (ie, diabetes mellitusl, and dogs with increased β-cell responsiveness to glucagon (ie, insulin resistance). Plasma C-peptide concentrations during glucagon stimulation testing were variable in diabetic dogs and may represent dogs with type-1 and type-2 diabetes or, more likely, differences in severity of β-cell loss in dogs with type-1 diabetes. J Vet Intern Med 1996;10:116–122. Copyright © 1996 by the American College of Veterinary Internal Medicine.     

Hemostatic Abnormalities in Dogs With Hemangiosarcoma

The hemostasis profiles of 24 dogs with histologically confirmed hemangiosarcoma were prospectively evaluated. Microangiopathic hemolysis was defined as the presence of schistocytes; disseminated intravascular coagulation was defined as 1) thrombocytopenia, 2) fibrin(ogen) degradation products greater than 10 micrograms/mL, 3) prolongation of one or more coagulation times (activated partial thromboplastin time or one-stage prothrombin time) by greater than 25% of the control, 4) fragmented red blood cells (greater than or equal to 1+ based on a semiquantitative grading scale), and 5) fibrinogen less than or equal to 80 mg/dL. Three of the five criteria listed above had to be met for disseminated intravascular coagulation to be diagnosed. Fifty percent of the dogs were considered to have disseminated intravascular coagulation at presentation. Thrombocytopenia was present in 75% of the dogs and was the most common abnormality. The mean platelet count was 137,800/microL. Twenty-five percent of the dogs died as a result of the hemostatic abnormalities. Only 12% of the dogs had microangiopathic hemolysis without other evidence of disseminated intravascular coagulation. Hemostatic abnormalities are present in many dogs with hemangiosarcoma at the initial clinical presentation and represent an important clinical finding.     

Levamisole Reduces the Thrombocytopenia Associated with Myxovirus Vaccination

Mature dogs were vaccinated with a myxovirus vaccine. At this time, half of the dogs were also given a subcutaneous injection of levamisole hydrochloride (2.2 mg/kg). Blood platelets were counted daily. The dogs that had received only the vaccine showed, after 48 hours, a 48% decrease in platelets. Levamisole reduced the thrombocytopenia associated with myxovirus vaccination. Levamisole could have a protective effect on platelets by preventing their aggregation induced by viral neuraminidase.     

Intracranial Lesions in Dogs With Hemangiosarcoma

A retrospective analysis of 85 dogs with hemangiosarcoma (HSA) that underwent complete necropsy, including gross examination of the brain, was conducted. Grossly identifiable intracranial lesions were present in 17 dogs. Twelve of 85 dogs (14.2%) had brain metastases. Four of 85 dogs (4.7%) had hemorrhagic lesions and/or ischemic necrosis without identifiable tumor. One dog had a primary central nervous system tumor. Signs of intracranial disease were present in six of 85 dogs (7.1%) with HSA; four had brain metastases and two had nonneoplastic lesions. Metastases had a propensity for cerebrum and gray matter. Dogs with brain metastases had more widely disseminated disease than dogs without brain metastases (P less than 0.001). Dogs with pulmonary metastases were at greater risk for developing brain metastases than dogs without pulmonary metastases (odds ratio = 8.31). Although thoracic radiography accurately identified ten of 12 dogs (83%) with pulmonary metastases, too few cases were available to assess the applicability/accuracy of thoracic radiography in predicting the presence or absence of brain metastases in dogs with malignancy and signs of intracranial disease.     

Platelet Hyperfunction in Dogs With Malignancies

In vitro platelet aggregometry was performed on whole blood samples from 59 dogs with malignancies and 24 control dogs. Three reagents were used for the aggregation studies: collagen, arachidonic acid, and adenosine diphos-phate (ADP). The parameters measured to evaluate response to collagen included delay in the aggregation response, slope of the aggregation curve, maximum aggregation, and adenosine triphosphate (ATP) secretion. The platelets of dogs with malignancies exhibited significantly ( P < .05) shorter delays in the aggregation response, higher maximum aggregation, and higher ATP secretion when compared to control dogs. For the weaker reagents, ADP and arachidonic acid, the lowest concentration resulting in aggregation was determined. Platelets of dogs with malignancies tended to aggregate in response to lower concentrations of ADP than did those of controls ( P < .05). The response of platelets to the concentrations of arachidonic acid employed in this study was poor, with few samples achieving measurable aggregation. The findings of this study suggest that dogs with malignancies have hyperaggregable platelets.