Thrombocytopenia Associated With Neoplasia in Dogs

Ten percent (214/2,059) of all dogs with cancer at North Carolina State University Veterinary Teaching Hospital had thrombocytopenia. The thrombocytopenia was associated with infectious/inflammatory etiologies in 4%, miscellaneous disorders (therapy, bone marrow failure, disseminated intravascular coagulation) in 35%, and neoplasia without identifiable secondary factors in 61% of cancer-bearing dogs. Classifying these dogs by tumor groups revealed the following proportionate ratios: lymphoid, 29%; carcinoma, 28%; sarcoma, 20%; hemic neoplasia, 7%; multiple, 5%; unclassified, 3%; benign, 3%; brain, 3%; and endocrine, 3%. Dogs with hemangiosarcoma, lymphoma, and melanoma were at increased risk of developing thrombocytopenia. Cytotoxic therapy was the major factor increasing the risk of thrombocytopenia in dogs with melanoma. Golden Retrievers were the only breed recognized with a predisposition to develop thrombocytopenia. If thrombocytopenia is identified in a dog with cancer, we recommend thorough evaluation of the coagulation system before surgery or therapy, and careful consideration of the risks and potential benefits of myelosuppressive or L-asparaginase therapy.     

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.     

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.     

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.     

Anemia Is Associated with Decreased Survival Time in Dogs with Lymphoma

Background: Anemia is a common complication in human patients with neoplasia and has been associated with decreased survival time and a poorer quality of life.
Hypothesis: The presence of anemia at diagnosis is negatively associated with survival and remission times in dogs with lymphoma, but not in dogs with osteosarcoma.
Animals: Eighty-four dogs with lymphoma and 91 dogs with osteosarcoma that presented for treatment at the Animal Cancer Center, Colorado State University.
Methods: Retrospective, case-control study. Medical records were reviewed to determine the presence or absence of anemia (PCV < 40) at initial presentation. Median survival and remission times were identified by the Kaplan-Meier product limit method and the association between anemia and survival was determined by a multivariable Cox proportional hazard regression analysis.
Results: Cancer-related anemia is more frequent in dogs with lymphoma than in control dogs or dogs with osteosarcoma. Dogs with lymphoma and anemia had a significantly decreased survival time compared with dogs without anemia. There was no effect of anemia on remission time in dogs with lymphoma. Anemic dogs with osteosarcoma did not have decreased survival or remission time compared with nonanemic dogs with osteosarcoma.
Conclusions and Clinical Importance: Shortened survival time in dogs with lymphoma and anemia at initial presentation has important prognostic significance. Understanding cancer-related anemia in dogs might offer new opportunities to improve quality of life and survival times in these patients.     

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.     

Comparison of Axillary And Heating Block Methods of Activated Clotting Time (ACT) in Dogs

The activated clotting time (ACT) is commonly used in veterinary medicine as an assessment of dysfunction within the intrinsic clotting cascade. Performing the test requires little techincal expertise and no special equipment except for a heating block or constant temperature waterbath, neither of which is routinely found in veterinary practices. The purpose of this study was to determine whether performing the test using a human axilla as the heat source was accurate for both normal dogs and clinically ill dogs (with prolonged ACT's) when compared to using a heating block as the head source. The results of this study reveal that the axillary method of ACT determination has acceptable clinical agreement with the heating block method. Thus, the axillary method of ACT determination is an acceptable alternative when no constant temperature heating source is available.     

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.     

Ultrasonographic Characteristics of the Adrenal Glands in Dogs With Pituitary-Dependent Hyperadrenocorticism: Comparison With Normal Dogs

Ultrasonographic evaluation of the adrenal glands was performed in 10 dogs with pituitary-dependent hyperadrenocorticism (PDH) and in 10 age- and weight-matched healthy control dogs. Thickness, shape, and echogenicity were determined for each adrenal gland. Adrenal thickness in dogs with PDH (median, 10 mm-left; 8.5 mm-right) was significantly greater than thickness in control dogs (median, 6 mm-left; 6 mm-right). Other ultrasonographic characteristics associated with PDH included bilaterally symmetrical adrenomegaly and maintenance of normal adrenal shape. Adrenal echogenicity was homogeneous and less than that of the adjacent renal cortex in 8 of 10 dogs with PDH and in 10 of 10 control dogs. Heterogenous echogenicity was present in 2 of 10 dogs with PDH, and was associated with nodular cortical hyperplasia in one of those dogs. Results of this study confirm the difference in sonographic appearance between PDH-induced bilateral cortical hyperplasia and functional adrenocortical neoplasia, and show a difference in so-nographically determined adrenal size between healthy dogs and dogs with PDH. J Vet Intern Med 1996; 10:110–115. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

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.     

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.     

Factitious Hyperkalemia in Dogs With Thrombocytosis

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.     

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.