The effect of ε-aminocaproic acid on blood product requirement, outcome and thromboelastography parameters in severely thrombocytopenic dogs.

BACKGROUND: No treatment other than platelet administration is known to protect against spontaneous hemorrhage in thrombocytopenic dogs. OBJECTIVES: Primary: determine if treatment with ε-aminocaproic acid (EACA) decreases the requirement for blood transfusions and improves outcome in dogs with severe thrombocytopenia. Secondary: find evidence of hyperfibrinolysis and determine the effect EACA administration on rapid (rTEG) and tissue plasminogen activator-spiked (tPA-rTEG) thromboelastography parameters. ANIMALS: Twenty-seven dogs with severe thrombocytopenia were treated with EACA, and data from an additional 33 were obtained from the hospital database as historical control (HC) cohort. METHODS: Single arm clinical trial with HCs. The EACA group dogs received EACA (100 mg/kg IV followed by a constant-rate infusion [CRI] of 400 mg/kg/24 hours). Thromboelastography before and during EACA infusion, hospitalization days, number of transfusions, and mortality were compared. RESULTS: No difference was found in number of transfusions per dog (median, interquartile range; 1, 0-2.5 vs 0.9, 0-2; P = .5) and hospitalization days (4, 4-6 vs 4.5, 3.75-6; P = .83) between HC and EACA groups, respectively, and no difference in survival was identified by log-rank analysis (P = .15). Maximum amplitude on both rTEG and tPA-rTEG increased after EACA administration (rTEG baseline: 23.6, 9.6-38.9; post-EACA: 27.3, 19.8-43.2; P < .001; tPA-rTEG baseline: 23, 10.9-37.2; post-EACA: 24.7, 16.7-44.8; P < .002). CONCLUSIONS AND CLINICAL IMPORTANCE: Although EACA increased clot strength, there was no effect on outcome. Treatment with EACA at this dosage cannot be recommended as a routine treatment but may be considered for dogs with severe ongoing hemorrhage.

Case report: Low dose dexmedetomidine infusion for the management of hypoglycemia in a dog with an insulinoma.

Objective: To describe the use of a low dose dexmedetomidine infusion as preoperative treatment for hypoglycemia secondary to a functional pancreatic tumor in a dog. Case summary: An 8.7-year-old castrated male Hungarian Vizsla presented for further evaluation of persistent hypoglycemia after the referring veterinarian established a tentative diagnosis of insulinoma based on paired insulin and glucose measurements. Abdominal ultrasound and computed tomography demonstrated evidence of a pancreatic mass with possible hepatic metastases. Attempts to aspirate the lesions under ultrasound guidance were unsuccessful, and the dog was hospitalized overnight for planned surgical resection of the presumed pancreatic tumor and biopsy of the hepatic lesions the following day. In response to a progressive increase in patient anxiety and agitation trazodone was prescribed ~5 mg/kg orally every 8 h and gabapentin at ~7 mg/kg every 8 h. As the dog continued to remain anxious dexmedetomidine at a dose of 1 mcg/kg was administered intravenously immediately followed with an infusion of dexmedetomidine at 1 mcg/kg/h. The anxious behaviors were successfully controlled with minimal cardiovascular side effects. Serial blood glucose measurements obtained during this time demonstrated euglycemia. The dog remained euglycemic while receiving dexmedetomidine for the remainder of the pre-operative period and for duration of hospitalization following surgical resection and biopsy. New or unique information provided: This case report demonstrates a possible role for dexmedetomidine to counteract hypoglycemia in dogs with insulinomas.

Fluid Overload.

Fluid overload (FO) is characterized by hypervolemia, edema, or both. In clinical practice it is usually suspected when a patient shows evidence of pulmonary edema, peripheral edema, or body cavity effusion. FO may be a consequence of spontaneous disease, or may be a complication of intravenous fluid therapy. Most clinical studies of the association of FO with fluid therapy and risk of harm define it in terms of an increase in body weight of at least 5-10%, or a positive fluid balance of the same magnitude when fluid intake and urine output are measured. Numerous observational clinical studies in humans have demonstrated an association between FO, adverse events, and mortality, as have two retrospective observational studies in dogs and cats. The risk of FO may be minimized by limiting resuscitation fluid to the smallest amount needed to optimize cardiac output and then limiting maintenance fluid to the amount needed to replace ongoing normal and pathological losses of water and sodium.

Comparison of venous hemoglobin saturation measurements obtained by in vivo oximetry and calculated from blood gas analysis in critically ill dogs.

OBJECTIVE: To compare in vivo central venous hemoglobin saturation measurement (ScvO2 ) using a fiber optic catheter with saturation calculated from blood gas analysis in critically ill dogs. DESIGN: Prospective observational study. SETTING: University veterinary teaching hospital intensive care unit. ANIMALS: A convenience sample of 20 dogs with severe illness. INTERVENTIONS: Dogs were instrumented with either a central venous catheter with an integrated fiber optic cable or a conventional catheter with a fiber optic probe inserted through its distal port. Baseline saturation was measured with the fiber optic system (FSO2 ), then monitored continuously. Central venous blood was collected for analysis and FSO2 was recorded by the principal investigator (PI) or nursing staff participating in data collection (staff) at baseline and at 1, 2, 3, and 6 hours. Hemoglobin oxygen saturation (SO2 ) values calculated using human Bohr coefficients were taken directly from the analyzer (GPSO2 ), and were also calculated using temperature-correction and canine Bohr coefficients (RSO2 ). MEASUREMENTS AND MAIN RESULTS: Ninety-seven paired measurements from 20 dogs were analyzed. FSO2 obtained by the PI (n = 41) had better agreement with both GPSO2 (concordance correlation coefficient ρc = 0.926 vs 0.5562) and RSO2 (ρc = 0.75 for PI vs 0.54) than did staff (n = 56). RSO2 values were always smaller than GPSO2 . FSO2 - GPSO2 differences were smaller when measurements were collected by the PI versus Staff (mean difference 0.21 vs -6.6, respectively, P < 0.02). Thirty-six of 41 FSO2 values obtained by PI were within 5% of GPSO2 . CONCLUSIONS: Concordance between FSO2 and either calculation method was low, but was better when performed by PI. The larger difference between methods when using RSO2 suggests a positive bias by FSO2 . Difficulty obtaining stable measurements may have contributed to the poor concordance between methods within Staff.

Venous oxygen saturation in critical illness.

OBJECTIVE: To review clinically relevant features of systemic oxygen delivery and consumption and the technique and use of venous oxygenation monitoring in human and veterinary medicine. DATA SOURCES: Veterinary and human peer-reviewed medical literature including scientific reviews, clinical and laboratory research articles, and authors' clinical research experience. SUMMARY: Measurement of venous hemoglobin oxygen saturation (venous oxygenation) provides insight into the balance between oxygen supply and tissue demand. In people, measurement of venous oxygen saturation can reveal decompensation that is missed by physical examination and other routinely monitored parameters. Therefore, measurement of mixed or central venous oxygenation measurement may help guide therapy and predict outcome of critically ill patients. In dogs, low central venous oxygen saturation has been associated with impaired cardiopulmonary function and poor outcome in several small studies of experimental shock or severe clinical illness, suggesting that monitoring this variable may assist the treatment of severe illness in this species as well. CONCLUSION: Venous oxygenation reflects systemic oxygenation status and can be used to guide treatment and estimate prognosis in critically ill patients. Measurement of venous oxygenation in veterinary patients is feasible and is a potentially valuable tool in the management of patients with severe disease. This review is intended to increase the understanding and awareness of the potential role of venous oxygen measurement in veterinary patients.

Maintenance Fluid Therapy: Isotonic Versus Hypotonic Solutions.

The goal of maintenance fluid therapy in small animals is to replace normal ongoing losses of water and salts when oral intake is withheld. Hospitalized dogs and cats may have multiple stimuli for antidiuretic hormone release that disrupt normal osmoregulation and predispose to water retention. Severe illness promotes retention of both sodium and water as edema. Commercially available fluids have electrolyte concentrations that are very different from dietary maintenance requirements, and potential consequences include development of hypoosmolality, edema, or both when excesses of water or sodium are administered. Suggestions for tailoring fluid administration toward specific goals are provided.

Opinions of clinical veterinarians at a US veterinary teaching hospital regarding antimicrobial use and antimicrobial-resistant infections.

OBJECTIVE: To determine opinions of faculty members with clinical appointments, clinical veterinarians, residents, and interns at a US veterinary teaching hospital regarding antimicrobial use and antimicrobial-resistant infections. DESIGN: Cross-sectional survey. SAMPLE: 71 veterinarians. PROCEDURES: An online questionnaire was sent to all veterinarians with clinical service responsibilities at the North Carolina State University veterinary teaching hospital (n = 167). The survey included 23 questions regarding demographic information, educational experiences, current prescribing practices, and personal opinions related to antimicrobial selection, antimicrobial use, restrictions on antimicrobial use, and antimicrobial resistance. RESULTS: Of the 167 veterinarians eligible to participate, 71 (43%) responded. When respondents were asked to rate their level of concern (very concerned = 1; not concerned = 5) about antimicrobial-resistant infections, most (41/70 [59%]) assigned a score of 1, with mean score for all respondents being 1.5. Most survey participants rated their immediate colleagues (mean score, 1.9) as more concerned than other veterinary medical professionals (mean score, 2.3) and their clients (mean score, 3.4). Fifty-nine of 67 (88%) respondents felt that antimicrobials were overprescribed at the hospital, and 32 of 69 (46%) respondents felt uncomfortable prescribing at least one class of antimicrobials (eg, carbapenems or glycopeptides) because of public health concerns. CONCLUSIONS AND CLINICAL RELEVANCE: Findings indicated that veterinarians at this teaching hospital were concerned about antimicrobial resistance, thought antimicrobials were overprescribed, and supported restricting use of certain antimicrobial classes in companion animals. Findings may be useful in educating future veterinarians and altering prescribing habits and antimicrobial distribution systems in veterinary hospitals.

Red blood cell storage lesion.

OBJECTIVE: To summarize current understanding of the mechanisms responsible for changes occurring during red blood cell (RBC) storage, collectively known as the storage lesion, and to review the biological and clinical consequences of increasing storage time of RBCs. DATA SOURCES: Human and veterinary clinical studies, experimental animal model studies, and reviews of the RBC storage lesion with no date restrictions. HUMAN DATA SYNTHESIS: Experimental studies have characterized the evolution of human RBC and supernatant changes that occur during storage and form the basis for concern about the potential for harm from long-term storage of RBCs. Although 4 randomized controlled trials of varying sizes failed to find an association between RBC storage time and negative clinical outcomes, a recent meta-analysis and numerous observational clinical studies have demonstrated that transfusion of old versus fresh stored RBCs is associated with an increased risk of morbidity and mortality, particularly among trauma victims and cardiac surgery patients. Potential clinical consequences of RBC transfusion following development of the storage lesion include risk of organ dysfunction, organ failure, infections, and death. VETERINARY DATA SYNTHESIS: Experimental animal models have contributed to the evidence supporting adverse consequences of the RBC storage lesion. Studies on relevant RBC storage issues such as the effect of different preservative solutions and leukoreduction have been completed. Transfusion with RBCs stored for 42 days increases mortality in dogs with experimental sepsis. CONCLUSION: Storage of RBCs induces progressive biochemical, biomechanical, and immunologic changes that affect red cell viability, deformability, oxygen carrying capacity, microcirculatory flow, and recipient response. Most reports in the human and veterinary literature support the concept that there are deleterious effects of the RBC storage lesion, but additional studies with improved experimental design are needed to identify compelling reasons to modify current blood banking and transfusion practices.

Variability of performance of wound infusion catheters.

OBJECTIVE: To compare the distribution of flow from two commercial and one handmade multihole wound infusion catheters. STUDY DESIGN: Open label experimental measurement of flow distribution in a bench top apparatus of handmade (n = 10) and two commercial (n = 10 each) wound infusion catheters with 5-6'' (12-15.2 cm) long diffusion surfaces. METHODS: The distribution of 6 mL of distilled water injected at three different injection speeds (0.5, 5, and 120 minutes) through individual triangular pieces of felt cloth fitted over six contiguous regions of the diffusion surface of each catheter was measured in triplicate. RESULTS: The distribution of flow through the six regions was significantly more uniform at the two faster injection speeds. Ninety two per cent of the 120 minute infusion trials resulted in one or more regions producing negligible flow (<5% of total output), and in 16% of the 120 minute trials all the flow came from just one or two regions. CONCLUSIONS: Constant-rate infusions of 3 mL hour(-1) provide erratic distribution of flow from wound infusion catheters in a bench top apparatus. Commercial catheters did not outperform handmade catheters. CLINICAL RELEVANCE: Uneven distribution of flow at low infusion speeds may contribute to inconsistent or unsatisfactory pain relief in patients treated with continuous wound infusions of local anesthetics.

Effect of intravenous administration of dextrose on coagulation in healthy dogs.

OBJECTIVE: To investigate effects of IV administration of dextrose on coagulation in healthy dogs. ANIMALS: 7 dogs. PROCEDURES: Thromboelastography and coagulation panel analysis were used to assess coagulation. Samples (S1 through S9) were collected during the study phases: phase 0 (S1 [baseline]); phase 1 (S2 and S3), infusion of crystalloid fluid without dextrose; phase 2 (S4 and S5), high-rate dextrose infusion; phase 3 (S6, S7, and S8), moderate-rate dextrose infusion; and phase 4 (S9), discontinuation of fluids for 24 hours. In phase 3, dogs were allocated to 2 groups; 1 was administered dextrose at a rate comparable to total parental nutrition (40% of resting energy requirement; group A), and 1 was administered dextrose at rates equaling 70% to 90% of resting energy requirement (group B). Blood glucose concentration was measured every 2 hours. RESULTS: No dogs had clinically relevant sustained hyperglycemia. Maximum amplitude and elastic shear modulus were significantly lower at S6 than at S1 through S4. Concentration of D-dimer was significantly higher at S6 than at S1, S3, and S4 and significantly higher at S5 than at S3. Prothrombin time was significantly prolonged at S3, S5, S7, S8, and S9, compared with the value at S1. Activated partial thromboplastin time was significantly prolonged at S5 and S6, compared with values at S1, S2, S3, S4, and S9. CONCLUSIONS AND CLINICAL RELEVANCE: IV administration of dextrose to healthy dogs at rates comparable to or higher than those for conventional parenteral nutrition resulted in mild but clinically unimportant interference with coagulation.

Evaluation of intermittent infusion of bupivacaine into surgical wounds of dogs postoperatively.

Thirty-one dogs were randomised to receive intermittent wound infusion of bupivacaine or saline after surgery. Wound pressure sensitivity, pain scores, body temperature, heart rate, respiratory rate, analgesic drugs administered, time to walking and time to eating after surgery were recorded. Plasma bupivacaine concentrations were measured. The relative frequency distributions of the non-interventional and interventional pain scores, but not the relative frequency distributions of palpation pain scores or wound pressure sensitivity, were significantly different between groups following surgery. There was a significant difference between groups in the time to eating and in the amount and timing of analgesic drugs administered. Measured plasma bupivacaine concentrations demonstrated systemic absorption of the drug. Bupivacaine infusion into surgical wounds after surgery may improve post-operative recovery, but no effect on wound tenderness was demonstrated in this study.

Item generation and design testing of a questionnaire to assess degenerative joint disease-associated pain in cats.

OBJECTIVE: To determine the items (question topics) for a subjective instrument to assess degenerative joint disease (DJD)-associated chronic pain in cats and determine the instrument design most appropriate for use by cat owners. ANIMALS: 100 randomly selected client-owned cats from 6 months to 20 years old. PROCEDURES: Cats were evaluated to determine degree of radiographic DJD and signs of pain throughout the skeletal system. Two groups were identified: high DJD pain and low DJD pain. Owner-answered questions about activity and signs of pain were compared between the 2 groups to define items relating to chronic DJD pain. Interviews with 45 cat owners were performed to generate items. Fifty-three cat owners who had not been involved in any other part of the study, 19 veterinarians, and 2 statisticians assessed 6 preliminary instrument designs. RESULTS: 22 cats were selected for each group; 19 important items were identified, resulting in 12 potential items for the instrument; and 3 additional items were identified from owner interviews. Owners and veterinarians selected a 5-point descriptive instrument design over 11-point or visual analogue scale formats. CONCLUSIONS AND CLINICAL RELEVANCE: Behaviors relating to activity were substantially different between healthy cats and cats with signs of DJD-associated pain. Fifteen items were identified as being potentially useful, and the preferred instrument design was identified. This information could be used to construct an owner-based questionnaire to assess feline DJD-associated pain. Once validated, such a questionnaire would assist in evaluating potential analgesic treatments for these patients.

Cross-sectional study of the prevalence of radiographic degenerative joint disease in domesticated cats.

OBJECTIVE: To determine the prevalence of radiographic signs of degenerative joint disease (DJD) in a randomly selected sample of domestic cats. STUDY DESIGN: Prospective observational study. ANIMALS: Client-owned cats. METHODS: Cats (n=100) from a single practice and equally distributed across 4 age groups (0-5; 5-10; 10-15, and 15-20 years old) were randomly selected (regardless of heath status) and sedated for orthogonal radiographic projections of all joints and the spine. Quasi-Poisson regression analysis was used to investigate the relationship between patient demographics, blood biochemistry, hematologic and urine analysis variables, and DJD severity. RESULTS: Most (92%) cats had radiographic evidence of DJD; 91% had at least 1 site of appendicular DJD and 55% had > or = 1 site of axial column DJD. Affected joints in descending order of frequency were hip, stifle, tarsus, and elbow. The thoracic segment of the spine was more frequently affected than the lumbosacral segment. Although many variables were significantly associated with DJD, when variables were combined, only the association between age and DJD was significant (P<.0001). For each 1-year increase in cat age, the expected total DJD score increases by an estimated 13.6% (95% confidence interval: 10.6%, 16.8%). CONCLUSION: Radiographically visible DJD is very common in domesticated cats, even in young animals and is strongly associated with age. CLINICAL RELEVANCE: DJD is a common disease of domesticated cats that requires further investigation of its associated clinical signs.

Coagulation effects of low molecular weight heparin compared with heparin in dogs considered to be at risk for clinically significant venous thrombosis.

OBJECTIVE: Compare the effects of 3 anticoagulation protocols on anti-factor Xa activity (AXa). DESIGN: Prospective, randomized, double-blind study. SETTING: University veterinary teaching hospital. ANIMALS: Eighteen dogs considered to be at risk for venous thrombosis. INTERVENTIONS: Each dog was randomly assigned to 1 of the following 3 groups (n=6/group) and was treated for 24 hours: low-dose heparin (LDH), high-dose heparin (HDH), and dalteparin (DP). Dogs in the LDH group received a constant rate infusion (CRI) of unfractionated heparin (UFH) at 300 U/kg/d, the HDH group received a bolus of 100 U/kg of UFH IV, then a CRI of 900 U/kg/day, and the DP group received 100 U/kg DP SC at 0, 12, and 24 hours. MEASUREMENTS AND MAIN RESULTS: A total of 54 samples for activated partial thromboplastin time (aPTT) and AXa assays were collected at 0, 4, and 28 hours. Six samples had an AXa >0.1 U/mL, 5 of those were from the HDH group at hour 4. Two samples from the HDH group at hour 4 had a prolonged aPTT (93 and 200 seconds) and the highest AXa (0.6 and 1.0 U/mL, respectively). Four additional dogs in the HDH group did not complete the study due to hemorrhage; none of the dogs completing the study showed signs of hemorrhage. CONCLUSIONS: Neither DP nor LDH increased AXa to values considered therapeutic in humans (0.5-1 and 0.35-0.75 U/mL, respectively), and both protocols appear to be inadequate to increase AXa in dogs with clinical illness. HDH increased AXa to this range in 2 of 6 dogs, but had unpredictable effects on aPTT and resulted in hemorrhage in some dogs.

Analgesia for the critically ill dog or cat: an update.

Acute pain reliably accompanies severe illness and injury, and when sufficiently severe, it can complicate the recovery of critically ill patients. Because acute pain is closely tied to the neurologic process of nociception, pharmacologic therapy is often essential and effective. This update focuses on two methods of treatment of acute pain-local anesthetic infusion and continuous intravenous infusion of multimodal agents-that can be layered on top of standard care with other drugs.

Vaginoscopic urinary catheter placement in female dogs.

Urinary catheter placement in dogs may be necessary for certain surgical procedures or for treatment of certain conditions. This column describes the vaginoscopic placement of an indwelling female urinary catheter and possible complications of catheter placement.

A canine model of septic shock: balancing animal welfare and scientific relevance.

A shock canine pneumonia model that permitted relief of discomfort with the use of objective criteria was developed and validated. After intrabronchial Staphylococcus aureus challenge, mechanical ventilation, antibiotics, fluids, vasopressors, sedatives, and analgesics were titrated based on algorithms for 96 h. Increasing S. aureus (1 to 8 x 10(9) colony-forming units/kg) produced decreasing survival rates (P = 0.04). From 4 to 96 h, changes in arterial-alveolar oxygen gradients, mean pulmonary artery pressure, IL-1, serum sodium levels, mechanical ventilation, and vasopressor support were ordered based on survival time [acute nonsurvivors (< or =24 h until death, n = 8) > or = subacute nonsurvivors (>24 to 96 h until death, n = 8) > or = survivors (> or =96 h until death, n = 22) (all P < 0.05)]. In the first 12 h, increases in lactate and renal abnormalities were greatest in acute nonsurvivors (all P < 0.05). Compared with survivors, subacute nonsurvivors had greater rises in cytokines and liver enzymes and greater falls in platelets, white cell counts, pH, and urine output from 24 to 96 h (all P < 0.05). Importantly, these changes were not attributable to dosages of sedation, which decreased in nonsurvivors [survivors vs. nonsurvivors: 5.0 +/- 1.0 vs. 3.8 +/- 0.7 ml x h(-1) x (fentanyl/midazolam/ medetomidine)(-1); P = 0.02]. In this model, the pain control regimen did not mask changes in metabolic function and lung injury or the need for more hemodynamic and pulmonary support related to increasing severity of sepsis. The integration into this model of both specific and supportive titrated therapies routinely used in septic patients may provide a more realistic setting to evaluate therapies for sepsis.

Evaluation of client-specific outcome measures and activity monitoring to measure pain relief in cats with osteoarthritis.

BACKGROUND: There are no validated systems for measuring pain from osteoarthritis in cats. HYPOTHESIS: Owner subjective assessments and an activity monitor (AM) can be used to detect pain in cats with osteoarthritis and to assess efficacy of treatments. ANIMALS: Thirteen cats older than 10 years old, with owner-assessed decreases in activity, painful arthritic joints, and clinically normal blood work were included and evaluated for 3 weeks. METHODS: A collar-mounted AM measured activity and a client-specific outcome measure (CSOM) questionnaire characterized the severity of impairment. Overall global quality of life was also evaluated for each treatment. In weeks 2 and 3, meloxicam (0.1 mg/kg, day 1; 0.05 mg/kg, days 2-5) or a placebo was administered in a blinded, randomized, cross-over manner to test the assessment systems. RESULTS: The cats had a median of 4 arthritic appendicular joints. Activity counts for the week when cats (complete data on activity; n=9) were administered meloxicam were significantly higher than at baseline (P = .02) but not after placebo (P = .06). Baseline activity counts were not significantly different from placebo (P = .6). The CSOM data (n=13) showed that owners considered their cats to be more active on meloxicam compared with baseline (P = .001) and placebo (P < .004), and more active on placebo than at baseline (P < .01). Global quality of life improved significantly with meloxicam (P < .042). CONCLUSIONS AND CLINICAL IMPORTANCE: Both an AM and a CSOM system can detect behavior associated with pain relief in cats that are arthritic. Objective activity data might allow subjective assessment systems to be validated for use in clinical studies.