Thrombocytes in vertebrates other than mammals, inter alia in fish, are analogues of platelets in mammals. In Osteichthyes, these cells take part in haemostatic processes, including aggregation and release reactions in cases of blood vessel damage, and in the immune response development as well. This paper discusses the development of thrombocytes in Osteichthyes, taking into account the need to make changes to the concept of grouping progenitor cells as suggested in the literature. The following pages present the morphological and cytochemical properties of thrombocytes as well as their defence functions, and also point out differences between thrombocytes in fish and platelets in mammals. The paper further highlights the level of thrombocytes’ immune activity observed in fish and based on an increased proportion of these cells in response to antigenic stimulation, on morphological shifts towards forms characteristic of dendritic cells after antigenic stimulation and on the presence of surface structures and cytokines released through, inter alia, gene expression of TLR receptors, MHC class II protein-coding genes and pro-inflammatory cytokines. The study also points out the need to recognise thrombocytes in Osteichthyes as specialised immune cells conditioning non-specific immune mechanisms and playing an important role in affecting adaptive immune mechanisms.

This report describes atypical chronic trypanosomosis in a three year male Spitz dog. Fever, lethargy and anorexia were the early presenting signs without any hemato-biochemical abnormality. Peripheral blood smear examination was non-diagnostic on three consecutive times. Trypanosma evansi was confirmed in the Leishman stained thin blood smears (moderate parasetemia) on fourth parasitological examination. Biochemical profile showed a remarkable elevation in total serum bilirubin (6.7 mg%) and activities of alanine amino transferase (ALT) (950 IU/L) and alkaline phosphatase (AKP) (1050 IU/L) after a month. Anemia, leucopenia, neutropenia, lymphopenia and thrombocytopenia suggestive of bone marrow depression appeared by about 73 days of presentation of case. A rapid complete clinical recovery occurred within a week after treatment with quinapiramine sulphate and chloride combination @ 3.5mg/kg bwt. Hemoglobin, leucocyte and thrombocyte count improved within six days, however, liver enzyme activity normalized slowly over three months.

Objective-To correlate tissue distribution with development of lesions after experimental infection with a virulent strain of noncytopathic bovine viral diarrhea virus (BVDV) type 2 in calves. Animals-Ten 14-day-old and two 2-month-old colostrum-deprived calves. Procedure-Calves were intranasally inoculated with BVDV type-2 strain 1373 from an outbreak of clinically severe bovine viral diarrhea (BVD). Two 14-day-old calves served as noninfected controls. Two calves each were euthanatized on postinoculation days 3, 6, and 12, and 1 each on days 8, 9, 13, and 14. Tissues were collected for immunohistologic and histologic examination. Results-Inoculated calves developed nonspecific clinical signs characterized by high fever and decreased numbers of leukocytes and thrombocytes. Viral antigen was detected focally in lymphoid tissues on day 3. On days 6, 8, 9, 12, and 14, viral antigen became increasingly widespread throughout organs and tissues. Viral antigen in lymphoid tissues was associated with severe depletion of all compartments. Lesions in other tissues were not well correlated with distribution of viral antigen. Depletion of lymphoid tissues was observed in a calf on day 13, but viral antigen had been cleared from most tissues and was detected in vascular walls only. Conclusions and Clinical Relevance-Infection with a virulent BVDV strain resulted in wide dissemination of viral antigen in host tissues. Severe lymphoid depletion developed in lymphoid tissues, whereas viral antigen was generally not associated with lesions in other tissues. Findings suggest that development of lesions in acute BVD is not solely a function of viral replication and is also attributable to host reaction to infection.

Objective-To develop a flow cytometric assay for detection of platelet-bound IgG in dogs. Sample Population-Negative-control platelets were obtained from 5 clinically normal Greyhounds. Positive-control platelets were platelets from 1 clinically normal dog, sensitized with dog anti-canine platelet alloantibodies. Procedure-Washed platelets were incubated with mouse anti-canine IgG conjugated to fluorescein isothiocyanate and analyzed by flow cytometry. Optimal dilution of antibody reagent and dose-response were determined, as were effects on platelet-bound IgG detection of storage time and temperature of K3EDTA-anticoagulated blood samples, variable platelet numbers, and variable filling of K3EDTA evacuated tubes. Results-A 1:128 dilution of antibody reagent was optimal. There was a linear increase in platelet-bound IgG when normal canine platelets were incubated with increasing concentrations of positive-control serum. Variable numbers of positive-control platelets tested and variable filling of K3EDTA evacuated tubes had no significant effect on platelet-bound IgG concentration. Platelet-bound IgG concentration increased with storage time at room temperature (P = 0.0003), but not when blood was kept cool. Sufficient platelets for assay were able to be isolated from 3 ml of blood from 5 dogs with < 10,000 platelets/microliter. Conclusion-This assay for platelet-bound IgG in dogs is simple, repeatable, and practical. The assay is not affected by platelet count or variable filling of evacuated tubes, and requires only 3 ml of K3EDTA-anticoagulated blood. Blood samples for testing require packaging on ice and overnight delivery but, after arrival at the laboratory, can be refrigerated and analyzed within 72 hours of collection. Clinical Relevance-Assays for platelet-bound IgG may help in assessing causes and treatment of thrombocytopenia.

Effects of a single IV administered therapeutic dose of vincristine sulfate on platelet numbers and function were evaluated in 16 clinically normal dogs over the 2 weeks after drug administration. Results were statistically compared with those of a previous control study in which the same 16 dogs were administered saline solution (IV), instead of vincristine. Of the 16 dogs, 8 were orally administered daily immunosuppressive doses of prednisone concurrently throughout the saline-control and vincristine study periods. Platelet numbers and mean platelet volume were measured, using an automated hematology analyzer. Platelet function was evaluated by turbidimetric measurement of platelet aggregation in response to collagen, platelet-activating factor, and adenosine diphosphate (ADP), and by clot retraction (diluted whole-blood method) and buccal mucosa bleeding time. Vincristine had a significant (P < 0.05) effect on circulating platelet numbers. Vincristine induced a transient mild decrease in platelet numbers, followed by a moderate increase in numbers, with peak platelet count observed 8 days after drug administration. Mean platelet volume was not significantly affected by administration of vincristine. Vincristine had no significant effects on platelet aggregation in response to collagen, low or high doses of platelet-activating factor, and a high dose of ADP. The maximal degree of platelet aggregation attained in response to a low dose of ADP was not significantly affected by prior administration of vincristine. The maximal rate of platelet aggregation induced by a low dose of ADP after vincristine administration, however, was significantly (P < 0.05) lower than the rate of aggregation induced by a similar dose of ADP in the previous control study. Vincristine had no significant effects on clot retraction and bleeding time. Prednisone did not significantly affect platelet numbers and function, and did not modify vincristine's effects on the same variables.

The role of platelet-activating factor (PAF) in mediating the colonic damage that develops after large-colon torsion was studied in 14 ponies. Morphologic changes in areas of the ascending colon and selected abdominal and thoracic viscera after 1 hour of large-colon torsion and 3 to 5 hours of reperfusion were determined, as well as the protective effects of systemic administration of a specific PAF antagonist (WEB 2086). Ponies were selected then allocated at random and in equal numbers to 2 groups that received 1 of 2 treatments prior to induction of large-colon torsion: group 1 - control (saline solution), and group 2 WEB 2086 (3 mg/kg of body weight loading dose and 3 mg/kg/h for the remainder of the study). In each pony, full-thickness tissue specimens from the gastrointestinal tract-cecum, pelvic flexure, left and right ventral colon, and right dorsal colon - heart, left lung, liver, left adrenal gland, spleen, and right kidney were collected and histologically evaluated. Edema, mucosal necrosis, and neutrophil infiltration in colonic sections were graded from 0 (normal) to 3 (most severe changes). Sections of liver and lung from 3 ponies in each group, and colon from 1 pony in each group, also were examined by transmission electron microscopy to determine the presence of ultrastructural alterations. Ischemia and reperfusion induced marked changes in all sections of colon in all ponies: moderate to severe submucosal edema, moderate necrosis of the superficial epithelium and lamina propria, and necrosis of the mucosal crypt epithelium. Extra- vascular neutrophil accumulation was evident in all sections of colon and cecum, but not in other tissues. Ultrastructural lesions were not present in hepato- cytes or pneumocytes, or in the endothelial cells of liver, lung, and colon. Bacteria were observed by electron microscopy in 5% of hepatic sinusoids. Administration of a specific PAF antagonist, WEB 2086, failed to reduce severity of the observed lesions, indicating that it was not cytoprotective at the dosage used in this model of ischemia-reperfusion injury.

Sheep given powdered Ferula communis variety brevifolia at dosage of 2.5 g/kg of body weight/d for 15 days developed classical clinical signs of intoxication: anorexia, somnolence, apparent weakness, and hemorrhage. Marked reduction of vitamin K-dependent coagulation factors and prolongation of prothrombin time and activated partial thromboplastin time were consistent with presence of ferulenol, a toxic coumarinic factor in the plant. Changes induced in the coagulation system developed by the second day of plant administration and were normal within 4 days after dosing was stopped. There was no evidence of primary liver damage or platelet malfunction. Of 6 intoxicated sheep, 2 died with only minimal evidence of hemorrhage.

Platelet aggregation and adenosine triphosphate (ATP) release were measured by use of the impedance method in blood samples obtained from 25 adult female Beagles before and after sedation with acepromazine (0.13 mg/kg of body weight) and atropine (0.05 mg/kg), and during general anesthesia. General anesthesia was induced by IV administration of thiamylal (average dosage, 2.1 mg/kg, range, 1.2 to 4.2 mg/kg) and was maintained with halothane in oxygen. Samples of jugular venous blood were obtained from each dog, using citrate as anticoagulant. Platelet count was done on each sample. Platelet aggregation and ATP released from the aggregating platelets were measured within 2.5 hours of sample collection, using a whole-blood aggregometer. Adenosine diphosphate (ADP) or collagen was used as aggregating agent. For each aggregating agent, platelet aggregation and ATP release were measured over 6 minutes. After sedation with acepromazine and atropine, significant (P < 0.01) reduction was observed in platelet count (from median values of 341,000 cells/microliter to 283,000 cells/microliter) and in the ability of platelets to aggregate in response to ADP (from 14.0 to 7.0 Ohms). During the same period, maximal release of ATP in response to collagen also was reduced (from 5.56 micromoles to 4.57 micromoles; P < 0.01); however, this difference ceased to be significant when ATP release was normalized for platelet count. During general anesthesia and surgery (200 minutes after sedation), platelet count and aggregation responses to ADP and collagen had returned to presedation values. None of the dogs in this study appeared to have hemostasis problems during surgery. In conclusion, sedation with acepromazine and atropine induces measurable inhibition of ADP-induced platelet aggregation that resolves during subsequent general anesthesia and surgery. Transient inhibition of platelet aggregation is not manifested by a change in gross hemostasis during surgery.

Canine and human platelets (washed 4 times in a solution containing EDTA, prostaglandin E1, and theophylline to prevent release of alpha-granule constituents) were lysed by being frozen and thawed in the presence of detergent. Radioelectroimmunoassay for von Willebrand factor (vWf) in 5 human platelet lysates produced precipitin rockets, shaped like those produced from vWf in plasma from healthy human beings, and indicated that the mean von Willebrand factor antigen (vWf:Ag) content in platelets from healthy human beings was 526 +/- 87 human U/10(12) platelets. Radioelectroimmunoassay for vWf in platelet lysates from 17 healthy dogs with normal plasma vWf:Ag concentration produced precipitin rockets that looked different from those produced from canine plasma and indicated vWf:Ag content of 59 +/- 35 canine U/10(12) platelets. Inclusion of protease inhibitors in the lysing solution did not normalize the appearance of the precipitin rockets or substantially alter the measured platelet content of vWf:Ag. The array of vWf multimers revealed by sodium dodecyl sulfate-agarose gel electrophoresis of canine platelet lysates had a distinct appearance that differed from that of vwf in canine or human plasma and platelets; the intensity of the canine platelet vWf multimer bands was skewed, with relatively greater density in the lower molecular weight region and faint or undetectable multimer bands in the higher molecular weight region. Electrophoretograms with visible multimers in the high molecular weight region had vwf components that had higher molecular weight than did any vWf components in canine plasma. Radioelectroimmunoassay for fibronectin in these same canine platelet lysates indicated that the fibronectin content in platelets was 2.89 +/- 1.10 mg/10(12) platelets. An Airedale Terrier with type-I von Willebrand disease (vWd), but lacking clinical signs of vWd, had normal platelet content of vwf:Ag (28 +/- 12 canine U/10(12) platelets), whereas a German Shorthaired Pointer with moderately severe type-II vWd and a mildly affected Doberman Pinscher with type-I vWd had only a trace or undetectable amounts of vWf:Ag in their platelets. The concentration of vWf:Ag in platelet lysates from the Doberman Pinscher with vWd remained undetectable when the platelets were isolated from the Doberman Pinscher's blood mixed with citrated plasma from dogs with normal plasma vWf:Ag concentration. In all 3 dogs with vWd, platelet fibronectin content was within the normal range.

Immunochemical methods that are used to assess von Willebrand factor in human beings and dogs were used to assess von Willebrand factor in 3 cat species. Our findings indicated that the expression and multimeric composition of von Willebrand factor in plasma and platelets of cats were similar to those reported in human beings and dogs. We suggest that these methods may be used to evaluate von Willebrand disease in members of the cat family used in this study.