Comparison of preoperative to postoperative blood glucose in puppies undergoing elective surgical neutering.

The objective of this study was to determine if overnight fasting is associated with hypoglycemia in puppies undergoing elective surgical neutering. One hundred seventy-one apparently healthy puppies between the age of 2 and 6 months presented for elective surgical neutering. Owners were instructed to withhold food from puppies after midnight the night before surgery; water was to be freely available. Blood samples were collected pre- and postoperatively to determine blood glucose, packed cell volume (PCV), and serum total protein (TP). Pre- and postoperative data were compared with a paired Wilcoxon test (paired samples). Hypoglycemia was defined as glucose < 4.2 mmol/L (76 mg/dL) for pediatric puppies ≤ 16 weeks of age (n = 116), and < 3.6 mmol/L (65 mg/dL) for juvenile puppies > 16 weeks of age (n = 55). Blood glucose significantly increased after surgery from median 8.8 mmol/L (interquartile range [IQR], 1.7 mmol/L; range, 4.9-12.3 mmol/L) to a median 9.7 mmol/L (IQR, 1.8 mmol/L; range, 5.4-14.7 mmol/L; P < 0.0001). Preoperative median PCV was 35% (IQR, 6.5%; range, 26-53%) and TP was 58 g/L (IQR, 6 g/L; range, 44-82 g/L). Preoperative values were significantly higher than postoperative values for PCV (median, 31%; IQR, 4%; range, 24-43%) and TP (median, 55 g/L; IQR, 7 g/L; range, 40-76 g/L; P < 0.0001). No puppy developed hypoglycemia and no adverse events were observed or reported. Overnight fasting did not result in pre- or postoperative hypoglycemia in studied puppies undergoing elective neutering.

Effect of peri-operative crystalloid fluid rate on circulating hyaluronan in healthy dogs: A pilot study.

Hypervolemia can damage the endothelial glycocalyx, a key regulator of vascular permeability, coagulation and inflammation. A starting peri-operative crystalloid fluid rate of 5mL/kg/h is recommended for healthy dogs undergoing elective procedures but higher rates continue to be commonly used. This study aimed to determine if a higher starting perioperative fluid rate was associated with a greater increase in plasma concentrations of hyaluronan, a marker correlated with glycocalyx damage, in systemically healthy dogs undergoing elective surgical procedures. Based on a sample size calculation, 38 dogs undergoing ovariohysterectomy or castration were randomly assigned to receive lactated Ringer's at a starting perioperative fluid rate of 10mL/kg/h (n=19) or 5mL/kg/h (n=19). Plasma hyaluronan concentrations were measured by ELISA in pre- and post-fluid therapy samples. There were no significant differences between groups in hyaluronan values before (baseline, P=0.52) or after perioperative fluid administration (P=0.62). Compared to respective baseline values, hyaluronan values significantly increased following 5 and 10ml/kg/h fluid administration (P=0.02 for both comparisons). This preliminary study identified an increase in hyaluronan over the course of fluid therapy with both the low and high fluid rate. One possible explanation is that both fluid rates contribute to glycocalyx disruption, but it should be emphasized that hyaluronan is not specific to the glycocalyx. Further studies are needed to determine the origin of the increased circulating hyaluronan and its clinical significance in dogs undergoing elective surgical procedures.

Subconjunctival haemorrhage in 147 dogs.

OBJECTIVES: To identify differential diagnoses for subconjunctival haemorrhage in dogs. MATERIALS AND METHODS: Retrospective case series. RESULTS: Of 147 dogs with subconjunctival haemorrhage, 119 had a history of trauma. The most common types of injury were vehicular trauma (47/119) and dog attacks (32/119). Confirmed or suspected non-accidental injury was reported for 5/119. Of the 28 dogs without a history of trauma, 13 had a bleeding disorder and of these, immune-mediated thrombocytopenia was the most common diagnosis (9/13). Other causes included seizure disorders (4/28), vasculitis (3/28) and ocular or periocular disease (3/28). CLINICAL SIGNIFICANCE: Subconjunctival haemorrhage in dogs can be secondary to a wide range of injuries and systemic diseases, bleeding diathesis or ocular disease.

Extracellular vesicle concentration and procoagulant activity of canine haemoperitoneum fluid and packed red blood cells.

OBJECTIVES: To compare the concentration of phosphatidylserine-positive extracellular vesicles and phosphatidylserine-derived procoagulant activity of canine haemoperitoneum fluids and packed red blood cell units. MATERIALS AND METHODS: Ten dogs with haemoperitoneum (neoplasia = 7; trauma = 1; other = 2) were recruited, and five non-leukoreduced packed red blood cell units purchased. Supernatants were collected from haemoperitoneum samples and packed red blood cell units using a consistent centrifugation protocol. Phosphatidylserine-positive extracellular vesicle concentrations were measured by flow cytometry and phosphatidylserine-mediated procoagulant activity by a commercial thrombin generation assay. RESULTS: Phosphatidylserine-mediated procoagulant activity was significantly higher for supernatants collected from packed red blood cell units (median 54 nM, range 53 to 60 nM) than haemoperitoneum samples (median 43 nM; range 7 to 51 nM; P = 0.0007). By flow cytometry, the concentration of phosphatidylserine-positive extracellular vesicles was not significantly different between packed red blood cell (median: 415/µL, range 173 to 1331/µL) and haemoperitoneum samples (median: 314/µL, range 132 to 3880/µL; P = 0.77). CLINICAL SIGNIFICANCE: This study does not suggest that shed abdominal blood contains more extracellular vesicles with phosphatidylserine-mediated procoagulant activity than donor packed red blood cell units. Clinical studies to compare the effects of autologous transfusion of shed abdominal blood and packed red blood cell units on coagulation status and clinical outcome are required.

Development of a fibrinolysis assay for canine plasma.

Unbalanced coagulation and fibrinolysis leads to hemorrhage or thrombosis. Thromboelastography has been used to characterize hypo- and hyper-fibrinolysis in dogs, however the technique requires specialized instrumentation and proprietary reagents that limit its availability. The aim of this study was to develop a simple microplate method for assessment of fibrinolysis in canine plasma. Plasma from healthy dogs was mixed in a microwell plate with tissue factor, calcium, phospholipid and tissue plasminogen activator. Light absorbance was measured at regular intervals until return to baseline. Peak optical density (milli-absorption units, mAU), formation velocity (mAU/s), lysis velocity (mAU/s) and area under the curve (mAU.s) were calculated. The influence of potential interferents, variation in fibrinogen and ex vivo addition of heparin and aminocaproic acid on assay performance was determined. Inter-day coefficients of variation were ≤15% for all variables. Bilirubin≤1.88mg/dL and hemoglobin≤0.09mg/dL did not interfere with assay variables. Aminocaproic acid (40µg/mL) and heparin (0.125U/mL) caused almost complete inhibition of fibrinolysis and coagulation, respectively. All variables except lysis velocity (R2=0.08) were associated with fibrinogen concentration (R2>0.8). This assay showed acceptable performance characteristics for measurement of fibrinolysis in normal canine plasma. The assay utilizes small volume citrate plasma samples and readily available instrumentation and reagents, is not influenced by mild to moderate hemolysis or icterus and detects the presence of fibrinolysis inhibitors.

Urban environment: a risk factor for canine immune-mediated disease?

OBJECTIVES: To investigate whether dogs living in urban areas are more likely to develop immune-mediated disease than those in rural areas. MATERIALS AND METHODS: A case-control study comparing the prevalence of urban home location between dogs with immune-mediated disease and matched controls. Dogs diagnosed with immune-mediated haemolytic anaemia, immune-mediated thrombocytopenia, immune-mediated polyarthritis or meningoencephalomyelitis of unknown origin were identified by case record searches. Breed-matched dogs presenting to the same hospital during the same year as cases were randomly selected as controls. Home locations were classified as rural or urban using the population density of the relevant census tract and conditional logistic regression was used to examine association between home location and immune-mediated disease. RESULTS: In the 137 cases and 137 breed-matched controls, the odds ratio for any immune-mediated disease for dogs living in urban (versus rural) areas was 0·94 (95% confidence interval 0·58 to 1·55, P=0·80). Odds ratios for development of immune-mediated haematological diseases, immune-mediated polyarthritis or meningoencephalomyelitis of unknown origin were also not significantly different from the null value. Multivariable analysis including age, gender and season of presentation did not suggest confounding of effect of home location by these additional variables. CLINICAL SIGNIFICANCE: This study does not support an association between urban environment and immune-mediated disease in dogs.

Cell-Free DNA and DNase Activity in Dogs with Immune-Mediated Hemolytic Anemia.

BACKGROUND: Immune-mediated hemolytic anemia (IMHA) in dogs has a high risk of thrombosis and is associated with marked neutrophilia and necrosis. Cell death and release of neutrophil extracellular traps contribute to increased serum concentrations of cell-free DNA, and in human autoimmune disease reduced DNase activity further increases cell-free DNA. Free DNA in blood has prothrombotic properties and could contribute to hypercoagulability in IMHA. HYPOTHESIS: Cell-free DNA is elevated and DNase activity reduced in dogs with IMHA compared to healthy dogs. ANIMALS: Dogs presenting to two referral hospitals with IMHA (n = 28) and healthy controls (n = 20). METHODS: Prospective observational study. Blood was collected and death and thrombotic events occurring in the first 14 days after hospitalization recorded. DNA was extracted from plasma with a commercial kit and quantified by PicoGreen fluorescence. DNase activity of serum was measured by radial diffusion assay. RESULTS: Cell-free DNA was significantly higher in cases (median: 45 ng/mL, range: 10-2334 ng/mL) than controls (26 ng/mL, range 1-151 ng/mL, P = 0.0084). DNase activity was not different between cases and controls (P = 0.36). Four cases died and there were five suspected or confirmed thrombotic events. Cell-free DNA concentration was associated with death (odds ratio for upper quartile versus lower 3 quartiles: 15; 95% confidence interval 1.62-201; P = 0.03) but not thrombosis (P = 0.57). CONCLUSIONS AND CLINICAL IMPORTANCE: Cell-free DNA is elevated in dogs with IMHA and likely reflects increased release rather than impaired degradation of DNA. Cell-free DNA concentration is potentially associated with death and might be a prognostic indicator, but this requires confirmation in a larger population.