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  • Author or Editor: Maureen A. McMichael x
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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To evaluate the degree of activation of the contact pathway in citrated equine whole blood over holding times ≤ 30 minutes and assess effects of contact activation on recalcification-initiated thromboelastometry.

ANIMALS 11 healthy adult mixed-breed horses.

PROCEDURES Blood was collected by atraumatic jugular venipuncture into prewarmed evacuated siliconized glass tubes containing citrate anticoagulant and held at 37°C for ≤ 30 minutes. Thromboelastometry was performed with an in vitro viscoelasticity (thromboelastometry) monitoring system. Factor XII and factor XI procoagulant activities were determined in contemporaneously collected platelet-poor plasma samples by assessing changes in turbidity for 1 hour at approximately 25°C, with clotting times calculated by fitting a line to the steepest segment of the absorbance curve and determining its intersection with baseline. Effect of holding time on thromboelastometry parameters and plasma enzyme activity was evaluated by repeated-measures ANOVA on ranks. Association of procoagulant activities with coagulation time was determined by Spearman rank-order correlation analysis.

RESULTS Thromboelastometry parameters (coagulation time, clot formation time, α angle, and maximum clot firmness) reflected significant increases in coagulability during the holding period. Factor XII and factor XI procoagulant activities were significantly increased at 30 minutes, compared with 2 or 10 minutes (indicating contact activation of samples), and had significant negative correlation with coagulation time.

CONCLUSIONS AND CLINICAL RELEVANCE Ex vivo activation of the contact system in equine whole blood was evident, suggesting that recalcification of blood in the absence of a trigger is not an acceptable method of assessing the hemostatic system in horses.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To compare clinical signs, laboratory test results, and imaging findings between dogs with suspected anaphylaxis and dogs with sepsis.

DESIGN Retrospective case-case study.

ANIMALS 10 dogs with suspected anaphylaxis and 22 dogs with confirmed sepsis that met the criteria for systemic inflammatory response syndrome.

PROCEDURES Medical records for dogs in each group were reviewed and data extracted regarding signalment; reason for hospital admission; physical examination findings; results of CBC, serum biochemical analysis, coagulation testing, cytologic examination, and microbial culture; and imaging reports.

RESULTS All dogs in the anaphylaxis group fulfilled the criteria for systemic inflammatory response syndrome. Dogs in both groups had gastrointestinal signs, lethargy, mentation change, and bleeding abnormalities. Dogs with suspected anaphylaxis had a significantly higher eosinophil count and serum alanine aminotransferase activity and lower blood pH than dogs with sepsis. Dogs with sepsis had a significantly higher band neutrophil count, serum globulins concentration, and serum alkaline phosphatase activity and lower serum glucose concentration. Dogs in both groups had intracavitary free fluid and ultrasonographic findings of thickened intestines, gas or fluid-filled intestines, and a thickened gallbladder wall.

CONCLUSIONS AND CLINICAL RELEVANCE Clinical signs, laboratory values, and imaging findings may be similar in dogs with sepsis or anaphylaxis. Given the marked difference in prognosis and treatment, early differentiation is important. Anaphylaxis should be considered if a septic nidus cannot be identified, and supportive care should be considered for such patients.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate markers of in vivo platelet function (urinary 11-dehydro-thromboxane B2 [11-dehydroTXB2] and 2,3-dinorTXB2) and assess their response to administration of 2 commonly used dosages of aspirin in healthy dogs.

Animals—20 healthy dogs.

Procedures—Urine was collected prior to aspirin administration and on the morning following the last evening administration. Twenty dogs received aspirin (1 mg/kg, PO, q 24 h) for 7 consecutive doses. After a washout period of 5 months, 10 dogs received a single dose of aspirin (10 mg/kg, PO). Concentrations of urinary thromboxane metabolites 11-dehydroTXB2 and 2,3-dinorTXB2 were measured via ELISA, and values were normalized to urine creatinine concentration.

Results—Median baseline 11-dehydroTXB2 concentrations were 0.38 ng/mg of creatinine (range, 0.15 to 1.13 ng/mg). Mean ± SD baseline 2 at a 3-dinorTXB2 concentrations were 6.75 ± 2.77 ng/mg of creatinine. Administration of aspirin at a dosage of 1 mg/kg, PO, every 24 hours for 7 days did not significantly decrease urinary 11-dehydroTXB2 concentration, but administration of the single aspirin dose of 10 mg/kg did significantly decrease 11-dehydroTXB2 concentration by a median of 45.5% (range, 28.2% to 671%). Administration of the 1 mg/kg aspirin dosage significantly decreased urinary 2,3-dinorTXB2 concentration by a mean ± SD of 33.0 ± 23.7%. Administration of the single aspirin dose of 10 mg/kg also significantly decreased 2,3-dinorTXB2 concentration by a mean ± SD of 46.7 ± 12.6%.

Conclusions and Clinical Relevance—Aspirin administration (1 mg/kg/d) may be insufficient for reliable platelet inhibition in healthy dogs.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the components of canine whole blood samples that contribute to results of thromboelastometry (TEM).

Animals—127 healthy dogs.

Procedures—For each dog, a blood sample was collected from a jugular vein into tubes containing no anticoagulant, EDTA, or citrate anticoagulant. Citrated whole blood samples underwent TEM with tissue factor and TEM with ellagic acid. Indicators of RBC mass and platelet concentration were evaluated, and plasma coagulation tests were performed; data obtained were compared with results of TEM. For technical reasons, samples were not available from all dogs for all tests.

Results—Coagulation time was correlated with concentrations of primarily extrinsic pathway coagulation factors for TEM with tissue factor and with most factors via TEM with ellagic acid. Clot formation time, α angle, and maximum clot firmness were highly correlated with fibrinogen and platelet concentrations and some individual factor concentrations. Sample Hct was strongly correlated with most measured variables; low Hct was associated with relative hypercoagulability, and high Hct was associated with relative hypocoagulability.

Conclusions and Clinical Relevance—For TEM of canine blood samples, coagulation time was primarily a function of coagulation factor concentrations, whereas other variables were dependent on platelet and fibrinogen concentrations. Sample Hct strongly influenced the results of TEM, likely because RBCs act as a diluent for plasma coagulation factors. Thromboelastometry appeared to be affected by abnormalities of coagulation factors, platelet concentrations, and RBC mass. In samples from anemic patients, results of TEM indicative of hypercoagulability may be artifactual because of low RBC mass.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE

To determine the effects of a transdermal lidocaine patch (TLP) on indicators of postoperative pain in healthy dogs following ovariohysterectomy.

DESIGN

Randomized, blinded controlled trial.

ANIMALS

40 healthy shelter-owned female dogs admitted to a student surgery program for ovariohysterectomy.

PROCEDURES

Dogs were randomly assigned to receive after ovariohysterectomy a 5-cm-wide strip of TLP applied topically on both sides of the incision, for the full length of the incision and a wound dressing (n = 19) or a placebo patch (nonmedicated wound dressing; 21). All dogs underwent midline ovariohysterectomy. Immediately afterward, dogs received 2 IM morphine injections, carprofen (SC, q 12 h for 2 days), and the assigned patch (left in place for 18 hours). Postoperative comfort was evaluated by use of the short form of the Glasgow Composite Measures Pain Scale and serum cortisol concentrations measured prior to premedication and 1, 2, 4, 6, 8, 10, and 18 hours after surgery.

RESULTS

No significant difference in pain scores or serum cortisol concentrations was identified between dogs that received the TLP and dogs that received a placebo patch after ovariohysterectomy.

CONCLUSIONS AND CLINICAL RELEVANCE

The TLP provided no additional analgesic benefit to dogs treated concurrently with recommended doses of morphine and carprofen following ovariohysterectomy. Additional studies are needed to investigate whether similar results might be achieved in dogs treated concurrently with other analgesics. (J Am Vet Med Assoc 2017;250:1140–1147)

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine effects of IV transfusion with fresh (3-day-old) or stored (35-day-old) autologous erythrocyte concentrate on serum labile iron concentration, iron-binding capacity, and protein interaction with iron in dogs.

ANIMALS 10 random-source healthy dogs.

PROCEDURES Dogs were randomly assigned to receive autologous erythrocyte concentrate stored for 3 days (n = 5) or 35 days (5). One unit of whole blood was collected from each dog, and erythrocyte concentrates were prepared and stored as assigned. After erythrocyte storage, IV transfusion was performed, with dogs receiving their own erythrocyte concentrate. Blood samples were collected from each dog before and 5, 9, 24, 48, and 72 hours after transfusion. Serum was harvested for measurement of total iron, labile iron, transferrin, ferritin, hemoglobin, and haptoglobin concentrations.

RESULTS For dogs that received fresh erythrocytes, serum concentrations of the various analytes largely remained unchanged after transfusion. For dogs that received stored erythrocytes, serum concentrations of total iron, labile iron, hemoglobin, and ferritin increased markedly and serum concentrations of transferrin and haptoglobin decreased after transfusion.

CONCLUSIONS AND CLINICAL RELEVANCE Transfusion with autologous erythrocyte concentrate stored for 35 days resulted in evidence of intravascular hemolysis in healthy dogs. The associated marked increases in circulating concentrations of free iron and hemoglobin have the potential to adversely affect transfusion recipients.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the safety, efficacy, and effects on hemolymph gas analysis variables of sevoflurane anesthesia in Chilean rose tarantulas (Grammostola rosea).

Animals—12 subadult Chilean rose tarantulas of unknown sex.

Procedures—Spiders were anesthetized in a custom chamber with sevoflurane (5% in oxygen [1.0 L/min]), then allowed to recover in 100% oxygen. Righting reflex was evaluated every 3 minutes during anesthesia to determine time to anesthetic induction and recovery. Hemolymph samples were collected from an intracardiac location prior to and after induction of anesthesia and evaluated to determine various gas analysis variables.

Results—Mean ± SD induction and recovery times were 16 ± 5.91 minutes and 29 ± 21.34 minutes, respectively. Significant differences were detected for Po 2, base excess, and glucose and ionized magnesium concentrations between hemolymph samples obtained before anesthesia and those obtained after induction of anesthesia.

Conclusions and Clinical Relevance—Results of this study suggested that the use of sevoflurane as an anesthetic agent for Chilean rose tarantulas was safe and effective. Various hemolymph sample gas analysis values changed during anesthesia.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine the predominant thromboxane (TX) metabolite in urine of healthy cats, evaluate whether the method of sample collection would impact concentration of that metabolite, and propose a reference interval for that metabolite in urine of healthy cats.

ANIMALS 17 cats (11 purpose-bred domestic shorthair cats, 5 client-owned domestic shorthair cats, and 1 client-owned Persian cat).

PROCEDURES All cats were deemed healthy on the basis of results for physical examination, a CBC, serum biochemical analysis, urinalysis, and measurement of prothrombin time and activated partial thromboplastin time. Voided and cystocentesis urine samples (or both) were collected. Aliquots of urine were stored at −80°C until analysis. Concentrations of TXB2, 11-dehydroTXB2, and 2,3 dinorTXB2 were measured with commercially available ELISA kits. Urinary creatinine concentration was also measured.

RESULTS 11-dehydroTXB2 was the most abundant compound, representing (mean ± SD) 59 ± 18% of the total amount of TX detected. In all samples, the concentration of 11-dehydroTXB2 was greater than that of 2,3 dinorTXB2 (mean, 4.2 ± 2.7-fold as high). Mean concentration of 11-dehydroTXB2 for the 17 cats was 0.57 ± 0.47 ng/mg of creatinine. A reference interval (based on the 5% to 95% confidence interval) of 0.10 to 2.1 ng of 11-dehydroTXB2/mg of creatinine was proposed for healthy cats.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, 11-dehydroTXB2 was the major TX metabolite in feline urine. Measurement of this metabolite may represent a noninvasive, convenient method for monitoring in vivo platelet activation in cats at risk for thromboembolism.

Full access
in American Journal of Veterinary Research

Abstract

Case Description—A 5-year-old castrated male domestic shorthair cat was examined because of presumptive lidocaine intoxication. Thirty minutes earlier, the cat had received an SC injection of approximately 140 mg of lidocaine hydrochloride (20 mg/kg [9.1 mg/lb]) to facilitate closure of a wound on the left pelvic limb.

Clinical Findings—Initial physical examination revealed severe lethargy and respiratory distress; erratic, poor-quality pulses with severe hypotension; and pulmonary edema.

Treatment and Outcome—Initial supportive treatment included administration of oxygen and IV administration of lactated Ringer's solution. Additional treatment with a 20% lipid emulsion (1.5 mL/kg [0.68 mL/lb], IV) delivered over a 30-minute period resulted in dramatic improvement in cardiovascular and behavioral variables. No adverse effects from lipid emulsion were detected on routine hematologic evaluation, thoracic radiography, or computed tomography.

Clinical Relevance—IV administration of a lipid emulsion was used in the treatment of lidocaine intoxication in a cat. Rapid infusion of a lipid emulsion may be a therapeutic option for veterinary patients with toxicosis attributable to local anesthetics or other lipid-soluble drugs.

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in Journal of the American Veterinary Medical Association