Comparison of tissue factor-activated versus citrated native thromboelastography in dogs with suspected hemostatic abnormalities.

Viscoelastic testing methods, including thromboelastography (TEG) and rotational thromboelastometry, have an advantage over traditional tests of coagulation due to their ability to reflect in vivo hemostasis and predict need for transfusion of blood products more accurately. TEG in clinical settings is most often performed on citrated whole blood samples that are recalcified at the time of analysis, with or without the addition of an activator of coagulation. To date, superiority of the use of an activator in canine patients with abnormal hemostasis has not been demonstrated. We compared the use of tissue factor-activated (TF) TEG with citrated native (CN) TEG in dogs with suspected hemostatic abnormalities. Forty-five of 79 enrolled dogs with suspected abnormal hemostasis had an abnormal MA value. There was very high correlation between CN samples and TF-activated samples for alpha, K, MA, and R; there was a high correlation for LY30 and LY60. Categorical agreement for CN- and TF-activated TEG classification of hypercoagulable and hypocoagulable cases based on MA was good to very good, with 91% and 97% categorical agreement, respectively. No difference was found in the variance for any TEG variable between the 2 methods of analysis. For canine patients with suspected abnormal hemostasis, use of CN or TF-activated TEG appears acceptable. Monitoring of coagulation should be done with the same method; methods may not be used interchangeably.

Abdominal ultrasound has inconsistent agreement with subsequent surgery or necropsy findings in dogs and cats with septic peritonitis.

OBJECTIVE: To evaluate whether abdominal ultrasound correctly diagnosed septic peritonitis and correctly identified its causative lesion in dogs and cats. ANIMALS: 84 client-owned dogs and 10 cats that underwent an abdominal ultrasound and had confirmation of septic peritonitis via exploratory laparotomy or necropsy. METHODS: This retrospective case series documented abdominal ultrasound findings, surgical or necropsy findings, and method for initial diagnosis of septic peritonitis, if different from surgery or necropsy. The surgical report and necropsy findings were compared to sonography results to confirm a diagnosis of septic peritonitis. The frequency at which sonography diagnosed septic peritonitis and its causative lesion was calculated for each type of lesion pathology and organ system. Secondary aims included evaluating the effect of patient characteristics (body weight and species) on sonographic results and whether lesion type or location affected mortality. RESULTS: Most lesions causing septic peritonitis (70.2%) were gastrointestinal in origin and were nonneoplastic ulcerations or perforations (50%). Abdominal ultrasound diagnosed 56.3% of cases of subsequently confirmed septic peritonitis and correctly identified 67% of the causative lesions. Lesions of the gastrointestinal tract and ulcerations/perforations were the most frequent correct sonographic diagnoses and most likely to lead to a correct sonographic diagnosis of septic peritonitis. Lesions located in the hepatobiliary system and lesion types other than neoplasia or ulcerations/perforations were the most frequently missed by abdominal ultrasound. CLINICAL RELEVANCE: Abdominal ultrasound often fails to diagnose septic peritonitis or the underlying causative lesion, and its accuracy depends on the affected organ and type of lesion.

Abnormalities detected on digital rectal examinations in dogs are common and influence diagnostic and treatment plans.

OBJECTIVE: To determine the frequency of abnormal findings on digital rectal examination (DRE) performed during physical examinations at a tertiary referral veterinary hospital, to establish what abnormal findings are most common and whether they impact diagnostic and treatment plans, and to assess whether patient signalment or admitting service influences the frequency of abnormalities. ANIMALS: Client-owned dogs (n = 440). METHODS: Veterinarians performed DREs on dogs as part of a physical examination. Patient signalment and DRE findings were recorded in a standardized survey. Findings were deemed normal or abnormal and described. Whether the findings changed the diagnostic or treatment plan was also recorded. RESULTS: Abnormalities were detected on DRE in 160 of 440 (36%) dogs. Changes to the diagnostic plan occurred in 41 of 160 (26%) cases when an abnormality was found. Changes to the treatment plan occurred in 20 of 160 (12.5%) cases when an abnormality was found. Age (P = .2), sex (P = .9), and breed (P = 1) did not significantly influence the frequency of abnormal findings. Abnormal findings were significantly more common in dogs presenting to the emergency service than elective services (P = .005). CLINICAL RELEVANCE: Among dogs presenting to a tertiary veterinary hospital, abnormalities found on DRE are common and change the diagnostic plan in 1 out of 4 dogs and treatment plan in 1 out of 8 dogs. This study supports the continued practice of DREs in dogs, especially in emergency settings, regardless of signalment.

Total serum and ionized magnesium concentrations in healthy and hospitalized dogs.

OBJECTIVE: To determine if an association between ionized magnesium (iMg) and total magnesium (tMg) exists in healthy and hospitalized dogs admitted through an emergency service and to assess the associations between iMg and tMg with total protein, albumin, ionized calcium, and total calcium. DESIGN: Prospective cohort study. SETTING: Veterinary teaching hospital. ANIMALS: Sixty-nine dogs were enrolled. The healthy control group (group 1) included 24 dogs, and the hospitalized group (group 2) included 45 dogs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: For both groups, signalment, a venous blood gas, and serum biochemistry were obtained. In addition, the presumptive diagnosis was recorded for group 2. Blood was obtained prior to any therapeutic interventions. Group 1 tMg was within the reference interval (RI), and the values for iMg were used to provide a healthy group range (HGR) of 0.44-0.50 mmol/L. Group 2 tMg was within the RI, but iMg was below the calculated HGR range (group 2 median iMg = 0.4 mmol/L; range = 0.27-0.70). There was a significant positive correlation between iMg and tMg in each group (group 1: r = 0.6713, P = 0.0003; group 2: r = 0.5312, P = 0.0002). Ionized Mg and tMg were not significantly associated with any of the other evaluated variables in either group. CONCLUSIONS: Ionized Mg and tMg were significantly associated in both healthy and hospitalized dogs, but the relationship was weaker in the hospitalized dogs compared with the healthy population. For hospitalized dogs, the relationship was weak enough to question the validity of using iMg and tMg interchangeably to track magnesium status.

Comparison of a viscoelastic point-of-care coagulation monitor with thromboelastography in sick dogs with hemostatic abnormalities.

BACKGROUND: Viscoelastic coagulation monitor (VCM-Vet) is a point-of-care device that has been used to characterize hemostatic abnormalities in sick pets but has not been validated in veterinary patients. OBJECTIVES: We aimed to compare VCM-Vet and thromboelastography (TEG) in sick dogs with suspected disorders of hemostasis. METHODS: Duplicate VCM-Vet tests using untreated native blood performed concurrently on two VCM-Vet machines, and simultaneous TEG tests were performed (one citrated native (CN), and one activated with tissue factor (TF) at a 1:3600 dilution). Each VCM-Vet result was compared with both TF-activated and CN TEG. RESULTS: Fifty-three dogs were enrolled. Eleven cases displayed apparent hyperfibrinolysis. Spearman correlation coefficients for individual VCM-Vet devices and CN and TF TEG were obtained between R and CT values and ranged from 0.21 to 0.27, CFT and K (r = 0.60-0.67), angles (r = 0.51-0.62), and MCF and MA (r = 0.85-0.87). Comparison of the two VCM-Vet devices displayed positive correlations for all clot formation parameters with Lin's concordance correlation coefficients of 0.75-0.95. Variable lysis parameter agreement existed between the VCM-Vet devices and VCM-Vet and TEG. When samples were classified as hypercoagulable or coagulopathic, VCM-Vet had a low positive predictive value (17-33%) for the detection of hypercoagulable states and a moderate negative predictive value (64-74%) for the detection of coagulopathy as defined by TEG. CONCLUSIONS: VCM-Vet and TEG had variable correlations in clot formation values and a strong correlation for final clot strength. More information is needed to make conclusions about the lysis parameters. Artifact in the fibrinolysis portion of the test can confound the interpretation of VCM-Vet results.

Presumptive renal tubular acidosis secondary to topiramate administration in a cat.

OBJECTIVE: To describe renal tubular acidosis (RTA) and secondary acquired hyperaldosteronism in a cat as an adverse effect of topiramate therapy. CASE SUMMARY: An 8-year-old neutered female cat on chronic oral topiramate therapy at a recommended dose (11.9 mg/kg q 8 h) for seizure control was presented with severe metabolic acidosis and hypokalemia. Plasma electrolyte and acid-base analysis identified a severe metabolic acidosis (pH 7.153, reference interval: 7.31-7.46), hypokalemia (2.08 mmol/L [2.08 mEq/L], reference interval: 3.5-4.8 mmol/L [3.5-4.8 mEq/L]), and ionized hypercalcemia (1.85 mmol/L [1.85 mEq/L], reference range: 1.1-1.4 mmol/L [1.1-1.4 mEq/L]). Urinalysis revealed a urine specific gravity of 1.021 and a pH of 7.0. Diagnostic workup suggested distal RTA as a cause of the cat's acid-base and electrolyte disturbances. Aldosterone concentration was moderately increased, suggestive of secondary hyperaldosteronism. The metabolic abnormalities resolved with supportive care and discontinuation of topiramate. NEW OR UNIQUE INFORMATION PROVIDED: Topiramate is suggested to have led to the development severe RTA in a cat.

The effect of analytical temperature on thromboelastography tracings in dogs.

Viscoelastic testing methods such as thromboelastography (TEG) are becoming increasingly available to veterinarians in a clinical setting. TEG is useful in determining therapeutic transfusion needs and assessing global abnormalities of hemostasis of patients, given that it provides a more comprehensive assessment of coagulation than traditional tests. TEG is standardly performed at 37°C, which is considered a normal body temperature for human patients; however, 37°C is lower than normal body temperature for most canine patients. In an in vitro study, we investigated the potential effect that this difference in body temperature and test temperature might have on TEG results. Citrated blood samples were collected from clinically normal, as well as sick, dogs with various body temperatures. Samples were analyzed concurrently at the patient's body temperature and at 37°C. There was very high correlation between TEG performed at body temperature and at 37°C for R (min) and MA (mm), high correlation for K (min) and alpha angle (deg), and moderate correlation for LY30 (%) and LY60 (%). For canine patients with normal to mildly abnormal body temperatures, performance of TEG at the standard 37°C is acceptable.

Utility of the Sonoclot analyzer to assess hyperfibrinolysis in dogs.

BACKGROUND: Coagulation abnormalities, including hyperfibrinolysis, have been documented in sick veterinary patients. Viscoelastic tests, including the Sonoclot Coagulation and Platelet Function Analyzer, are useful in detecting hyperfibrinolysis. Tissue plasminogen activator (tPA) assays have been used to quantify fibrinolysis using thromboelastography. OBJECTIVES: We aimed to document and evaluate changes in the whole blood of healthy dogs exposed to in vitro tPA at varying concentrations using the Sonoclot analyzer. METHODS: Ten milliliters of blood was collected from healthy adult dogs. Sonoclot tests were run in duplicate and included a control sample and five tPA concentrations: 50, 75, 100, 150, and 200 IU/mL of blood. RESULTS: Eleven dogs were enrolled in the study. Based on standard Sonoclot Signature changes, a numeric value fibrinolysis time (FTi) was derived to aid in the quantification of hyperfibrinolysis. Activated clotting time and clot rate Sonoclot values were not significantly affected by any tPA concentration. There was a significant decrease in platelet function (PF) at tPA concentrations equal to and above 75 IU/mL on channel 1 and tPA concentrations of 150 IU/mL and higher on channel 2. There was a progressive decrease in FTi at increasing tPA concentrations. CONCLUSIONS: The Sonoclot analyzer can be used to evaluate hyperfibrinolysis. Predictable changes were seen in the Sonoclot Signature and a decrease in PF and FTi was found with increasing tPA concentrations. The Sonoclot assay with a tPA concentration of 100 IU/mL is suggested a baseline measure of hyperfibrinolysis and has a resultant median FTi of 42 minutes, which is a practical time for clinical applications.

Establishment of normal reference intervals in dogs using a viscoelastic point-of-care coagulation monitor and its comparison with thromboelastography.

BACKGROUND: Viscoelastic coagulation devices are a useful adjunct to the evaluation of hemostasis in veterinary patients. VCM Vet is a point-of-care device that is simple in operation and could be used to diagnose and trend hemostatic abnormalities in sick patients. VCM Vet does not use activators. OBJECTIVES: We aimed to establish reference intervals (RIs) for VCM Vet in a healthy adult canine population and concurrently perform thromboelastographic (TEG) analysis on these samples with and without tissue factor (TF) activation for RI comparisons. METHODS: Duplicate VCM Vet tests were performed immediately upon sample collection. Two concurrent TEG tests were performed on the remaining blood, one citrated, untreated (CU), and one activated with TF at a 1:3600 dilution. RESULTS: Fifty-two dogs were enrolled in the study. The following RIs were generated for VCM Vet machine 1 and 2, respectively: clot time (CT) (seconds) 163-480 and 172-457; clot formation time (CFT) (seconds) 104-288 and 94-252, α-angle (degrees) 41-65 and 44-66, and maximum clot firmness (MCF) (no units) 27-43 and 30-46. Moderate to good correlations were observed between the two machines with Lin's concordance correlation coefficients of 0.51-0.9 and a P < 0.002. TEG RIs were similar to previously reported values. CONCLUSIONS: VCM Vet RIs were generated. Each VCM Vet device should have a unique RI established due to inter-device variability. Direct correlations of VCM Vet values with TEG parameters were not performed due to the narrow range of the normal values and the need to evaluate patients with a wide range of hemostatic abnormalities.

Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE): Domain 5-Discontinuation of anticoagulant therapy in small animals.

OBJECTIVES: To systematically evaluate the evidence supporting the timing and mechanisms of permanent or temporary discontinuation of antiplatelet or anticoagulant medications in small animals DESIGN: Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality (poor, fair, or good), and development of consensus on conclusions via a Delphi-style survey for application of the concepts to clinical practice. SETTINGS: Academic and referral veterinary medical centers. RESULTS: Databases searched included Medline via PubMed and CAB abstracts. Two specific courses of inquiry were pursued, one focused on appropriate approaches to use for small animal patients receiving antiplatelet or anticoagulant drugs and requiring temporary discontinuation of this therapy for the purposes of invasive procedures (eg, surgery), and the other aimed at decision-making for the complete discontinuation of anticoagulant medications. In addition, the most appropriate methodology for discontinuation of heparins was addressed. CONCLUSIONS: To better define specific patient groups, a risk stratification characterization was developed. It is recommended to continue anticoagulant therapy through invasive procedures in patients at high risk for thrombosis that are receiving anticoagulant therapy, while consideration for discontinuation in patients with low to moderate risk of thrombosis is reasonable. In patients with thrombosis in whom the underlying cause for thrombosis has resolved, indefinite treatment with anticoagulant medication is not recommended. If the underlying cause is unknown or untreatable, anticoagulant medication should be continued indefinitely. Unfractionated heparin therapy should be slowly tapered rather than discontinued abruptly.

Evaluation of thoracic radiographs as a screening test for dogs and cats admitted to a tertiary-care veterinary hospital for noncardiopulmonary disease.

Thoracic radiographs are used as a screening tool for dogs and cats with a variety of disorders that have no clinical signs associated with thoracic structures. However, this practice has never been supported by an evidence-based study. The objective of this retrospective observational study was to determine if certain canine and feline populations have a higher proportion of radiographic abnormalities, and whether any of these abnormalities are associated with patient hospitalization and outcome. Patients were excluded if current or previous examinations revealed evidence of primary respiratory or cardiac disease, malignant neoplasia, or an abnormal breathing pattern consistent with pulmonary pathology. Any notable thoracic change in the radiology report was considered important and evaluated in this study. One hundred and sixty-six of these included patients were dogs and 65 were cats. Of the 166 dog radiographs evaluated, 120 (72.3%) had normal thoracic radiographs, while 46 (27.7%) had radiographic abnormalities. Of the sixty-five cats included, 36 (55.4%) had normal radiographs, while 29 (44.6%) had abnormal radiographs. Canine patients with abnormal radiographs had a significantly higher lactate level (P-value 0.0348) and feline patients with abnormal radiographs had a significantly lower packed cell volume (P-value 0.012). A large proportion of patients that had screening thoracic radiographs (32.5%) had documented abnormalities, but a relatively low percentage (6.5%) of our total population had their clinical plan changed as a consequence of detection of these abnormalities. Findings indicated that abnormal screening thoracic radiographs are more likely in dogs with an elevated lactate and cats with anemia, or a low normal hematocrit.

Disorders of micturition in small animal patients: clinical significance, etiologies, and management strategies.

OBJECTIVES: To review the physiology of micturition, the pathophysiology of micturition disorders, and current pharmacological agents used to treat these disorders. To discuss different urinary catheterization techniques, along with the risks of catheter-associated urinary tract infections attributed with these techniques. ETIOLOGY: Many critically ill veterinary patients are at risk of developing a number of neurological and non neurological micturition-related disorders. DIAGNOSIS: Micturition disorders can be diagnosed based on physical examination findings, urinary voiding contrast studies, urethral pressure profiles, and diagnostic testing such as urinalysis and urine cultures. THERAPY: Therapy can be either pharmacological, involvement of urinary catheterization, surgical, or a combination of all the above. The goal of the treatment is to correct the underlying causes resulting in the micturition-related disorder, and if possible, allow the patient to regain their normal physiological micturition behavior. PROGNOSIS: Depending on the underlying disease process and duration of the micturition disorder, the prognosis can be variable. In many instances, near-normal or normal function can return, but in severe cases, the patient may not regain its normal, appropriate micturition response.

Evaluation of acute traumatic coagulopathy in dogs and cats following blunt force trauma.

OBJECTIVE: To evaluate the presence of acute traumatic coagulopathy (ATC) in dogs and cats following blunt trauma and to relate coagulation variables with injury severity and admission variables. DESIGN: Prospective, single center, observational study from 2013 to 2014. SETTING: Urban private referral hospital. ANIMALS: Eighteen and 19 client-owned dogs and cats, respectively, sustaining blunt trauma within 8 hours of presentation without prior resuscitation; 17 healthy staff and client-owned control cats METHODS: Blood samples were collected upon presentation for measurement of blood gas, lactate, blood glucose, ionized calcium, PCV, total plasma protein, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, platelet count, and thromboelastography. RESULTS: ATC was diagnosed in 1 dog and 1 cat on presentation. Hypercoagulability was documented in 4/18 (22%) of dogs and 1/19 (5.3%) of cats. In dogs, prolongation of PT (P = 0.018), aPTT (P = 0.013) and decrease in maximum amplitude (MA) (P = 0.027) were significantly associated with injury severity as measured by the animal trauma triage (ATT) score. In cats, PT, aPTT, MA, and clot strength (G) were not associated with injury severity. In cats, increasing blood glucose and lactate were significantly associated with decreasing MA (P = 0.041, P = 0.031) and G (P = 0.014, P = 0.03). In both dogs (P = 0.002) and cats (P = 0.007), fibrinogen concentration was significantly correlated with G. CONCLUSIONS: ATC is rare in minimally injured dogs and cats following blunt trauma. In dogs, ATT score is significantly associated with PT, aPTT, and MA, suggesting an increased risk of ATC in more severely injured animals. ATT score does not appear to predict coagulopathies in cats. Future studies including more severely injured animals are warranted to better characterize coagulation changes associated with blunt trauma.

An in vitro comparison of the effects of voluven (6% hydroxyethyl starch 130/0.4) and hespan (6% hydroxyethyl starch 670/0.75) on measures of blood coagulation in canine blood.

OBJECTIVE: To assess primary and secondary hemostasis following in vitro dilution of canine whole blood (WB) with hydroxyethyl starch (HES) 130/0.4 and HES 670/0.75. DESIGN: In vitro experimental study. SETTING: Private practice, teaching hospital. ANIMALS: Twenty-five healthy dogs. INTERVENTIONS: Each dog underwent venipuncture and 18 mL of venous blood was sampled once. MEASUREMENTS AND MAIN RESULTS: Collected blood was separated in 4 aliquots. Aliquot A served as baseline sample. The remaining tubes of WB were diluted with 0.9% saline, HES 670/0.75 and HES 130/0.4 at a ratio of 1:5.5. Dilutional effects were evaluated using prothrombin time (PT), activated partial thromboplastin time (aPTT), packed cell volume (PCV), thromboelastography (TEG), and platelet closure time (Ct), which was measured using a platelet function analyzer (PFA). Clot strength (ie, G value) was calculated from measured TEG values. Significant increases in PT (P < 0.05) and aPTT (P < 0.05) were documented following WB dilution with saline. Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in significant hypocoagulable changes in K, MA and G (P < 0.05) compared to baseline and saline. When comparing saline to HES 670/0.75, both R and K values were significantly increased (P < 0.05). K value was significantly increased (P < 0.05) when comparing baseline to HES 130/0.4 and HES 670/0.75. Ct (P < 0.05) was significantly prolonged after WB dilution with HES solutions but not after saline. CONCLUSIONS: Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in changes in primary and secondary hemostasis. Although there were small differences between saline and HES 670/0.75, no differences between HES solutions were evident in this small study. This may suggest there would be minimal increases in bleeding risk when either solution is administered to dogs at low doses. Clinical relevance of our findings requires further investigation.