Amy M. Koenigshof

Systematic evaluation of evidence on veterinary viscoelastic testing Part 2: Sample acquisition and handling

Objective To examine systematically the evidence on sample acquisition and handling for the thrombo elastography (TEG) and rotational thromboelastometry (ROTEM) viscoelastic point of care instruments and to identify knowledge gaps. Design Six questions were considered, addressing sampling site, collection system, anticoagulant, collection procedure, and sample storage. Standardized, systematic evaluation of the literature was performed. Relevant articles were categorized according to level of evidence (LOE). Consensus was developed regarding conclusions for application of concepts to clinical practice. Setting Academic and referral veterinary medical centers. Results PubMed and CAB abstracts were searched. Eighteen papers were initially chosen; 5 of these papers applied to > 1 domain question. Three papers were used to address 2 questions each, and 2 papers were used to address 3 questions each. Most papers were judged LOE 3 (Good or Fair). Two of 5 papers were judged to be the same LOE each time they were used; 2 papers were judged to be LOE 3, Fair for 1 question and 3, Good for a second question; 1 paper used to address 3 questions was judged LOE 3, Good twice and 3, Fair once. Fourteen additional papers were evaluated post hoc during manuscript preparation. Conclusions Jugular venipuncture is recommended, but samples from IV catheters can be used. Consistent technique is important for serial sampling, and standardized sampling protocols are recommended for individual centers performing TEG/ROTEM. There is insufficient evidence to recommend use of a specific blood collection system, although use of evacuated blood tubes and 21-Ga or larger needles is suggested. Use of 3.2% buffered sodium citrate in a strict 1:9 ratio of citrate to blood is suggested. Suggested tube draw order is discard/serum, followed by citrate, EDTA, and then heparin. Samples should be held at room temperature for 30 minutes prior to analysis.OBJECTIVE To examine systematically the evidence on sample acquisition and handling for the thrombo elastography (TEG) and rotational thromboelastometry (ROTEM) viscoelastic point of care instruments and to identify knowledge gaps. DESIGN Six questions were considered, addressing sampling site, collection system, anticoagulant, collection procedure, and sample storage. Standardized, systematic evaluation of the literature was performed. Relevant articles were categorized according to level of evidence (LOE). Consensus was developed regarding conclusions for application of concepts to clinical practice. SETTING Academic and referral veterinary medical centers. RESULTS PubMed and CAB abstracts were searched. Eighteen papers were initially chosen; 5 of these papers applied to > 1 domain question. Three papers were used to address 2 questions each, and 2 papers were used to address 3 questions each. Most papers were judged LOE 3 (Good or Fair). Two of 5 papers were judged to be the same LOE each time they were used; 2 papers were judged to be LOE 3, Fair for 1 question and 3, Good for a second question; 1 paper used to address 3 questions was judged LOE 3, Good twice and 3, Fair once. Fourteen additional papers were evaluated post hoc during manuscript preparation. CONCLUSIONS Jugular venipuncture is recommended, but samples from IV catheters can be used. Consistent technique is important for serial sampling, and standardized sampling protocols are recommended for individual centers performing TEG/ROTEM. There is insufficient evidence to recommend use of a specific blood collection system, although use of evacuated blood tubes and 21-Ga or larger needles is suggested. Use of 3.2% buffered sodium citrate in a strict 1:9 ratio of citrate to blood is suggested. Suggested tube draw order is discard/serum, followed by citrate, EDTA, and then heparin. Samples should be held at room temperature for 30 minutes prior to analysis.

Effect of venipuncture quality on thromboelastography

Objective To determine if the quality of venipuncture impacts thromboelastography (TEG) results and if an initial discard tube mitigates any effects of traumatic venipuncture. Design Prospective, observational study. Setting Veterinary teaching hospital. Animals Fifteen privately owned and research colony adult dogs. Measurements Samples were collected from each jugular vein using 1 of 2 venipuncture techniques per vein. The venipuncture technique was randomized to the vein as follows: (1) “clean” venipuncture (CV) from 1 jugular vein, and (2) suboptimal venipuncture (SOV) from the opposite jugular vein. CV was defined as a direct entry into the vein on the first attempt. SOV was defined as needle insertion adjacent to the vein with redirection at least once to enter the vein. Two consecutive samples were collected from each venipuncture without removal of the needle, yielding 4 samples: CV1, CV2, SOV1, and SOV2. TEG was performed on each blood sample and the TEG parameters R, K, α, and MA were recorded. Results Mean ± SD of R for the SOV1 group (4.1 ± 1.3 s) was significantly shorter than that of the CV1 group (5.7 ± 1.4 s) and the SOV2 group (5.5 ± 1.9 s), P< 0.05. There was no difference in R between CV1 and CV2 groups, or between SOV2 and either CV1 or CV2. There was no significant difference in α, K, or MA among groups. Conclusions Mild-to-moderate venipuncture trauma had little effect on TEG overall, but R was significantly affected. Poorer quality collection resulted in a more rapid initiation of clot formation. However, the effect was mild and mitigated by testing samples in a second collection tube after discard of an initial sample.

Effects of delayed anticoagulation and use of evacuated tubes on non‐activated thrombelastography in dogs

BACKGROUND The effects of delayed anticoagulation and use of evacuated vacuum tubes in the collection of whole blood for nonactivated thrombelastography (TEG) are not known. OBJECTIVES The objective of this study was to examine the effects of delayed anticoagulation and use of vacuum-assisted blood collection tubes on results of nonactivated TEG. METHODS Twelve clinically healthy adult dogs were used in each of 3 studies. For each study, nonactivated TEG results from paired blood samples were compared. In study 1, the effect of delayed citrate anticoagulation was evaluated by collecting samples either into syringes containing citrate or into empty syringes followed by transfer to nonevacuated tubes containing citrate. In study 2, the effect of vacuum assistance in blood transfer was evaluated by collecting samples into syringes containing citrate and transferring either to nonevacuated plastic tubes or to evacuated plastic tubes. In study 3, the combined effects of delayed anticoagulation and vacuum assistance in blood transfer were evaluated by collecting samples into syringes containing citrate or into empty syringes followed by transfer to evacuated tubes containing citrate. Thrombelastographic analysis was performed in duplicate at 39°C after a 40-minute rest period. RESULTS The collection methods that delayed anticoagulation and/or used evacuated tubes yielded samples that appeared more coagulable compared with samples not exposed to delay or evacuated tubes. CONCLUSION Methods by which samples are collected affect results of nonactivated TEG and should be considered when establishing reference intervals, interpreting results, and publishing TEG results.

Retrospective evaluation of xylitol ingestion in dogs: 192 cases (2007–2012)

Objective To summarize the signalment, clinical signs, prevalence of decreased blood glucose concentration (BG), prevalence of increased liver values, treatment, and outcome in dogs known to have ingested xylitol. Design Retrospective study from December 2007 to February 2012 Setting Three university teaching hospitals. Animals One hundred ninety-two client-owned dogs with known or suspected xylitol ingestion. Interventions None. Measurements and Main Results The median ingested xylitol dose was 0.32 g/kg (range 0.03–3.64 g/kg). Clinical signs were present in 39 (20%) dogs on presentation to the veterinary teaching hospitals. The most common clinical sign was vomiting (n = 25), followed by lethargy (12). The median duration of clinical signs prior to presentation was 93 minutes (range 0–5,040 minutes). Dogs that developed clinical signs ingested a significantly higher dose of xylitol than those that were asymptomatic. Thirty dogs became hypoglycemic (BG ≤ 3.3 mmol/L [60 mg/dL]) at some time point during their hospitalization. When evaluating all dogs, there was a significant difference between the initial and lowest BGs. Thirty dogs had increased alanine aminotransferase activity or total serum bilirubin concentration. Dogs with increases in alanine aminotransferase activity or total serum bilirubin concentration had a significantly lower nadir BG. All dogs survived to discharge and 158 were known to be alive at 28 days. The rest were lost to follow up. Conclusions The prognosis for dogs evaluated by a veterinarian that ingest lower doses of xylitol and do not develop liver failure is excellent. Dogs ingesting xylitol should be hospitalized and monitored for variations in BG, because BG drops in most dogs following presentation. Additional studies are needed in dogs ingesting higher doses of xylitol before correlations between dose and the development of clinical signs or liver failure can be established. Treatment and prognosis for these dogs warrants further investigation.OBJECTIVE To summarize the signalment, clinical signs, prevalence of decreased blood glucose concentration (BG), prevalence of increased liver values, treatment, and outcome in dogs known to have ingested xylitol. DESIGN Retrospective study from December 2007 to February 2012 SETTING: Three university teaching hospitals. ANIMALS One hundred ninety-two client-owned dogs with known or suspected xylitol ingestion. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The median ingested xylitol dose was 0.32 g/kg (range 0.03-3.64 g/kg). Clinical signs were present in 39 (20%) dogs on presentation to the veterinary teaching hospitals. The most common clinical sign was vomiting (n = 25), followed by lethargy (12). The median duration of clinical signs prior to presentation was 93 minutes (range 0-5,040 minutes). Dogs that developed clinical signs ingested a significantly higher dose of xylitol than those that were asymptomatic. Thirty dogs became hypoglycemic (BG ≤ 3.3 mmol/L [60 mg/dL]) at some time point during their hospitalization. When evaluating all dogs, there was a significant difference between the initial and lowest BGs. Thirty dogs had increased alanine aminotransferase activity or total serum bilirubin concentration. Dogs with increases in alanine aminotransferase activity or total serum bilirubin concentration had a significantly lower nadir BG. All dogs survived to discharge and 158 were known to be alive at 28 days. The rest were lost to follow up. CONCLUSIONS The prognosis for dogs evaluated by a veterinarian that ingest lower doses of xylitol and do not develop liver failure is excellent. Dogs ingesting xylitol should be hospitalized and monitored for variations in BG, because BG drops in most dogs following presentation. Additional studies are needed in dogs ingesting higher doses of xylitol before correlations between dose and the development of clinical signs or liver failure can be established. Treatment and prognosis for these dogs warrants further investigation.

Effect of sorbitol, single, and multidose activated charcoal administration on carprofen absorption following experimental overdose in dogs

Objective To compare the effectiveness of single dose activated charcoal, single dose activated charcoal with sorbitol, and multidose activated charcoal in reducing plasma carprofen concentrations following experimental overdose in dogs. Design Randomized, four period cross-over study. Setting University research setting. Animals Eight healthy Beagles. Interventions A 120 mg/kg of carprofen was administered orally to each dog followed by either (i) a single 2 g/kg activated charcoal administration 1 hour following carprofen ingestion (AC); (ii) 2 g/kg activated charcoal with 3.84 g/kg sorbitol 1 hour following carprofen ingestion (ACS); (iii) 2 g/kg activated charcoal 1 hour after carprofen ingestion and repeated every 6 hours for a total of 4 doses (MD); (iv) no treatment (control). Measurements and Main Results Plasma carprofen concentrations were obtained over a 36-hour period following carprofen ingestion for each protocol. Pharmacokinetic modeling was performed and time versus concentration, area under the curve, maximum plasma concentration, time to maximum concentration, and elimination half-life were calculated and compared among the groups using ANOVA followed by Tukeys multiple comparisons test. Activated charcoal, activated charcoal with sorbitol (ACS), and multiple-dose activated charcoal (MD) significantly reduced the area under the curve compared to the control group. AC and MD significantly reduced the maximum concentration when compared to the control group. MD significantly reduced elimination half-life when compared to ACS and the control group. There were no other significant differences among the treatment groups. Conclusions Activated charcoal and ACS are as effective as MD in reducing serum carprofen concentrations following experimental overdose in dogs. Prospective studies are warranted to evaluate the effectiveness of AC, ACS, and MD in the clinical setting.OBJECTIVE To compare the effectiveness of single dose activated charcoal, single dose activated charcoal with sorbitol, and multidose activated charcoal in reducing plasma carprofen concentrations following experimental overdose in dogs. DESIGN Randomized, four period cross-over study. SETTING University research setting. ANIMALS Eight healthy Beagles. INTERVENTIONS A 120 mg/kg of carprofen was administered orally to each dog followed by either (i) a single 2 g/kg activated charcoal administration 1 hour following carprofen ingestion (AC); (ii) 2 g/kg activated charcoal with 3.84 g/kg sorbitol 1 hour following carprofen ingestion (ACS); (iii) 2 g/kg activated charcoal 1 hour after carprofen ingestion and repeated every 6 hours for a total of 4 doses (MD); (iv) no treatment (control). MEASUREMENTS AND MAIN RESULTS Plasma carprofen concentrations were obtained over a 36-hour period following carprofen ingestion for each protocol. Pharmacokinetic modeling was performed and time versus concentration, area under the curve, maximum plasma concentration, time to maximum concentration, and elimination half-life were calculated and compared among the groups using ANOVA followed by Tukeys multiple comparisons test. Activated charcoal, activated charcoal with sorbitol (ACS), and multiple-dose activated charcoal (MD) significantly reduced the area under the curve compared to the control group. AC and MD significantly reduced the maximum concentration when compared to the control group. MD significantly reduced elimination half-life when compared to ACS and the control group. There were no other significant differences among the treatment groups. CONCLUSIONS Activated charcoal and ACS are as effective as MD in reducing serum carprofen concentrations following experimental overdose in dogs. Prospective studies are warranted to evaluate the effectiveness of AC, ACS, and MD in the clinical setting.

Evaluation of two point-of-care ethylene glycol tests for dogs.

OBJECTIVE To evaluate 2 point-of-care ethylene glycol (EG) tests in dogs. DESIGN Prospective, randomized, blinded laboratory evaluation. SETTING University teaching hospital. ANIMALS Ten healthy adult dogs. INTERVENTIONS Jugular venipuncture and in vitro evaluation for detection of EG in canine blood. MEASUREMENTS Whole blood samples were centrifuged and separated, and the plasma was divided into 30 aliquots. The aliquots were mixed with EG to provide EG concentrations ranging from 0 to 100 mg/dL. The EG concentration of each sample was confirmed using gas chromatography. For the VetSpec EG Qualitative Reagent Test Kit, 100 μL of each sample was added to test vials and compared with 20 and 50 mg/dL reference vials. For the Kacey EG Test Strips, 20 μL of each sample was added to the test circle and compared with the color chart provided by the manufacturer. For each test, samples were prepared in groups of 5 and presented in randomized order to 2 readers who were blinded to the presumed EG concentration. Samples were scored as negative, 20-50 mg/dL, or greater than 50 mg/dL. For each test, the sensitivity and specificity for detecting EG was calculated. Cohens unweighted kappa coefficient was calculated to determine the degree of agreement between readers. MAIN RESULTS For detecting EG, the Kacey EG Test Strips had excellent sensitivity and specificity (both 100%) and good agreement between readers. The VetSpec EG Qualitative Reagent Test Kit was less sensitive and specific (65% and 70% for the first reader, 95% and 40% for the second) with less agreement. CONCLUSIONS Of the 2 systems evaluated, the Kacey EG Test Strips displayed greater accuracy and ease of use.

Retrospective evaluation of concurrent intra‐abdominal injuries in dogs with traumatic pelvic fractures: 83 cases (2008–2013)

Objective To report the occurrence of intra-abdominal injury (IA) in dogs with pelvic fractures due to blunt trauma, to evaluate for association between characterization of pelvic fractures and the presence of IA, and to evaluate for association between IA and other specific clinical conditions. Design Retrospective case series (2008–2013). Setting University teaching hospital. Animals Eighty-three client-owned dogs with pelvic fractures due to blunt trauma. Interventions None. Measurements and Main Results Pelvic injuries included pubic fractures (90.4%), ischial fractures (80.7%), sacroiliac luxations (57.8%), iliac fractures (43.4%), acetabular fractures (30.1%), and sacral fractures (13.3%). Thirty-one dogs (37%) had IA, which included hemoabdomen (27 dogs), uroabdomen (3), and septic abdomen (3); 2 dogs had 2 types of IA. Dogs with sacral fractures were significantly more likely to have IA than dogs without sacral fractures (P = 0.0162). Characterization of pelvic fractures included the direction of compression, presence of a weight-bearing bone fracture, and degree of pelvic narrowing, none of which had an association with IA (P > 0.05). Dogs were more likely to have IA if they had cardiac dysrhythmia (P = 0.0002) or hematuria (P = 0.0001), and were more likely to have a hemoabdomen if they had cardiac dysrhythmia (P = 0.0005). Dogs with hematochezia were more likely to have a septic abdomen (P = 0.0123). Dogs were more likely to receive a transfusion if they had AI (P = 0.033) or hemoabdomen specifically (P = 0.0033). Overall survival to discharge was 89%, which was significantly greater than survival in dogs with pelvic injury that also had septic abdomen (33%; P = 0.0299). Conclusions IA is common in dogs with pelvic fractures, especially those with sacral fractures. Pelvic fracture characterization had no bearing on the presence of IA.OBJECTIVE To report the occurrence of intra-abdominal injury (IA) in dogs with pelvic fractures due to blunt trauma, to evaluate for association between characterization of pelvic fractures and the presence of IA, and to evaluate for association between IA and other specific clinical conditions. DESIGN Retrospective case series (2008-2013). SETTING University teaching hospital. ANIMALS Eighty-three client-owned dogs with pelvic fractures due to blunt trauma. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Pelvic injuries included pubic fractures (90.4%), ischial fractures (80.7%), sacroiliac luxations (57.8%), iliac fractures (43.4%), acetabular fractures (30.1%), and sacral fractures (13.3%). Thirty-one dogs (37%) had IA, which included hemoabdomen (27 dogs), uroabdomen (3), and septic abdomen (3); 2 dogs had 2 types of IA. Dogs with sacral fractures were significantly more likely to have IA than dogs without sacral fractures (P = 0.0162). Characterization of pelvic fractures included the direction of compression, presence of a weight-bearing bone fracture, and degree of pelvic narrowing, none of which had an association with IA (P > 0.05). Dogs were more likely to have IA if they had cardiac dysrhythmia (P = 0.0002) or hematuria (P = 0.0001), and were more likely to have a hemoabdomen if they had cardiac dysrhythmia (P = 0.0005). Dogs with hematochezia were more likely to have a septic abdomen (P = 0.0123). Dogs were more likely to receive a transfusion if they had AI (P = 0.033) or hemoabdomen specifically (P = 0.0033). Overall survival to discharge was 89%, which was significantly greater than survival in dogs with pelvic injury that also had septic abdomen (33%; P = 0.0299). CONCLUSIONS IA is common in dogs with pelvic fractures, especially those with sacral fractures. Pelvic fracture characterization had no bearing on the presence of IA.

The effects of protamine sulfate on clot formation time and clot strength thromboelastography variables for canine blood samples

OBJECTIVE To determine the effects of protamine sulfate on clot formation time and clot strength thromboelastography variables for canine whole blood samples. ANIMALS Blood samples obtained from 11 healthy dogs. PROCEDURES Blood samples were collected from jugular veins of dogs into syringes with 3.2% sodium citrate (blood to citrate ratio, 9:1). Blood samples were divided into aliquots, and protamine sulfate was added to various concentrations (0 [control], 22, 44, and 66 μg/mL). Prepared samples were activated with kaolin (n = 8) or not activated (8), CaCl₂ was added, and thromboelastography was performed. Reaction time (R), clot formation time (K), rate of clot formation (α angle), and maximum amplitude (MA) were measured. RESULTS For kaolin-activated and nonactivated blood samples, protamine (66 μg/mL) significantly increased R and K and decreased α angle and MA, compared with values for control samples. Also, protamine (44 μg/mL) decreased MA in nonactivated blood samples and increased K and decreased α angle in kaolin-activated samples, compared with values for control samples. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated protamine prolonged clot formation time and decreased overall clot strength in a dose-dependent manner; such effects may contribute to a hypocoagulable state in dogs. Kaolin-activated and nonactivated blood samples were appropriate for measurement of the effects of protamine on coagulation. Administration of protamine to reverse the effects of heparin should be performed with caution.

Influence of immune-mediated hemolytic anemia on flow velocities in the portal vein and caudal vena cava measured by use of pulsed-wave Doppler ultrasonography in dogs

OBJECTIVE To compare blood flow velocities of the portal vein (PV) and caudal vena cava (CVC) measured by use of pulsed-wave Doppler ultrasonography in clinically normal dogs and dogs with primary immune-mediated hemolytic anemia (IMHA). ANIMALS 11 client-owned dogs admitted to a veterinary teaching hospital for management of primary IMHA and 21 staff- or student-owned clinically normal dogs. PROCEDURES Flow velocities in the PV and CVC at the porta hepatis were evaluated in conscious unsedated dogs with concurrent ECG monitoring; evaluations were performed before dogs with IMHA received heparin or blood transfusions. Three measurements of peak velocity at end expiration were obtained for each vessel, and the mean was calculated. Results were compared between IMHA and control groups. RESULTS Mean ± SD blood flow velocity in the CVC differed between control (63.0 ± 18.6 cm/s) and IMHA (104 ± 36.9 cm/s) groups. Variance in dogs with IMHA was significantly greater than that for the clinically normal dogs. No significant difference in blood flow velocity in the PV was detected between IMHA and control dogs. CONCLUSIONS AND CLINICAL RELEVANCE Higher blood flow velocities were detected by use of pulsed-wave Doppler ultrasonography in the CVC of dogs with naturally occurring IMHA and may be used to predict anemia in patients suspected of having IMHA.

Evaluation of the safety of early compared to late enteral nutrition in canine septic peritonitis

Septic peritonitis is a relatively common condition in the veterinary intensive care unit, with a classically high mortality rate. Early enteral nutrition (EEN) in critically ill humans can lead to improved outcome. This study was performed to determine the safety of early postoperative feeding in canine septic peritonitis. In this retrospective case series, 56 dogs were identified. Sixteen dogs received EEN, defined as nutrition within 24 hr of surgery; 27 received late enteral nutrition (LEN) defined as nutrition more than 24 hours following surgery; and 13 dogs had no enteral nutrition in hospital (NEN). Signalment, physical examination findings, and occurrence of pre-admission vomiting, regurgitation, and length of anorexia were the same amongst all groups. There was no significant difference in the number of gastrointestinal complications postoperatively between the EEN, LEN, and NEN groups or in the occurrence of vomiting/regurgitation postoperatively compared to preoperatively. There was no difference in the length of hospitalization between any group, although fewer dogs in the NEN group survived compared to the EEN/LEN combined group (46% [6/13] versus 81% [37/40]). This study indicates it is safe to initiate EEN without additional risk of gastrointestinal complications. Prospective studies are needed to evaluate the potential benefits of EEN in dogs with septic peritonitis.