Anthea L. Raisis

Comparison of invasive versus noninvasive blood pressure measurements before and after hemorrhage in anesthetized greyhounds using the Surgivet V9203

OBJECTIVE To determine the agreement between blood pressure obtained with a noninvasive technique and direct technique using the Surgivet V9203 at varying blood pressure levels created using a canine hemorrhage model. DESIGN Experimental study. SETTING University Teaching Hospital. ANIMALS Twenty-nine greyhounds with an average weight of 30 kg. Approval from the Murdoch University Animal Ethics Committee was obtained (R228609). METHODS Arterial blood pressure (BP) was measured noninvasively (NIBP) via a cuff placed over the dorsal metatarsal artery and via a catheter in the contralateral dorsal metatarsal artery (IBP). Retrospectively the blood pressure measurements recorded were divided into various BP categories. A total of 84 paired readings were obtained. The data were further analyzed with respect to heart rate [<120/min and >120/min]. Comparison of the measurements was performed using the Bland-Altman method. RESULTS For all categories, BP measurements were generally lower when recorded using the oscillometric technique [Systolic (Sys) bias 4.20 kPa (31.54 mm Hg), mean bias 0.52 kPa (3.93 mm Hg), and diastolic bias 1.04 kPa (7.83 mm Hg)]. Mean arterial BP had the least bias and greatest precision in the hypotensive group (bias 0.174 kPa (1.3063 mm Hg), precision 0.79 kPa (5.89 mm Hg)), low BP group (bias 0.62 kPa (4.67mm Hg) and precision 0.89 kPa (6.67mm Hg)) and normotensive group [bias 0.76 kPa (5.71 mm Hg) and precision 1.16 kPa (8.73 mmHg)]. CONCLUSIONS The results demonstrate that the agreement between NIBP measurements and IBP, are within the limits of agreement recommended by the American College of Veterinary Internal Medicine Hypertension Consensus Panel for all pressures except Sys BP. This suggests that mean and diastolic NIBP using the Surgivet V9203 are a clinically acceptable alternative of IBP in hypovolemic hypotensive dogs.

The effects of halothane and isoflurane on cardiovascular function in dorsally recumbent horses undergoing surgery

OBJECTIVE To determine the haemodynamic effects of halothane and isoflurane with spontaneous and controlled ventilation in dorsally recumbent horses undergoing elective surgery. STUDY DESIGN Prospective randomized clinical trial. ANIMALS Twenty-five adult horses, body mass 487 kg (range: 267-690). METHODS Horses undergoing elective surgery in dorsal recumbency were randomly assigned to one of four treatment groups, isoflurane (I) or halothane (H) anaesthesia, each with spontaneous (SB) or controlled ventilation (IPPV). Indices of cardiac function and femoral arterial blood flow (ABF) and resistance were measured using transoesophageal and transcutaneous Doppler echocardiography, respectively. Arterial blood pressure was measured directly. RESULTS Four horses assigned to receive isoflurane and spontaneous ventilation (SBI) required IPPV, leaving only three groups for analysis: SBH, IPPVH and IPPVI. Two horses were excluded from the halothane groups because dobutamine was infused to maintain arterial blood pressure. Cardiac index (CI) was significantly greater, and pre-ejection period (PEP) shorter, during isoflurane compared with halothane anaesthesia with both spontaneous (p = 0.04, p = 0.0006, respectively) or controlled ventilation (p = 0.04, p = 0.008, respectively). There was an association between CI and PaCO(2) (p = 0.04) such that CI increased by 0.45 L minute(-1)m(-2) for every kPa increase in PaCO(2). Femoral ABF was only significantly higher during isoflurane compared with halothane anaesthesia during IPPV (p = 0.0006). There was a significant temporal decrease in CI, but not femoral arterial flow. CONCLUSION The previously reported superior cardiovascular function during isoflurane compared with halothane anaesthesia was maintained in horses undergoing surgery. However, in these clinical subjects, a progressive decrease in CI, which was independent of ventilatory mode, was observed with both anaesthetic agents. CLINICAL RELEVANCE Cardiovascular function may deteriorate progressively in horses anaesthetized for brief (<2 hours) surgical procedures in dorsal recumbency. Although cardiovascular function is superior with isoflurane in dorsally recumbent horses, the need for IPPV may be greater.

Candida albicans peritonitis in a dog

Objective – To describe the clinical management of a case of Candida albicans peritonitis in a dog and discuss the pathogenicity of Candida peritonitis along with treatment using the fungistatic agent, fluconazole. Case Summary – A 15-week-old Papillon developed peritonitis secondary to enterectomy site dehiscence. A pure growth of Candida albicans was obtained from the abdominal fluid. Surgical repair of the dehiscence was performed and antifungal therapy instituted with fluconazole postoperatively. A marked exudative process was noted postoperatively with production of large volumes of fluid from the abdominal drain. Fresh frozen plasma and pentastarch were provided for oncotic support. Recovery was complicated by megaesophagus, however, the patient gradually improved and was discharged 11 days after surgery. New or Unique Information Provided – To our knowledge, this is the first case report of successful treatment of Candida albicans peritonitis in a dog. A marked exudative process was noted during therapy requiring significant oncotic support. Resolution of the disease process was achieved with surgical intervention and antifungal therapy.OBJECTIVE To describe the clinical management of a case of Candida albicans peritonitis in a dog and discuss the pathogenicity of Candida peritonitis along with treatment using the fungistatic agent, fluconazole. CASE SUMMARY A 15-week-old Papillon developed peritonitis secondary to enterectomy site dehiscence. A pure growth of Candida albicans was obtained from the abdominal fluid. Surgical repair of the dehiscence was performed and antifungal therapy instituted with fluconazole postoperatively. A marked exudative process was noted postoperatively with production of large volumes of fluid from the abdominal drain. Fresh frozen plasma and pentastarch were provided for oncotic support. Recovery was complicated by megaesophagus, however, the patient gradually improved and was discharged 11 days after surgery. NEW OR UNIQUE INFORMATION PROVIDED To our knowledge, this is the first case report of successful treatment of Candida albicans peritonitis in a dog. A marked exudative process was noted during therapy requiring significant oncotic support. Resolution of the disease process was achieved with surgical intervention and antifungal therapy.

Toxicity in three dogs from accidental oral administration of a topical endectocide containing moxidectin and imidacloprid

Three dogs were presented with a history of oral administration of a topical endectocide containing imidacloprid and moxidectin. They were diagnosed with imidacloprid and moxidectin intoxication, having ingested doses ranging from 7.5 to 1.4 mg/kg of imidacloprid and 1.9 to 2.8 mg/kg of moxidectin. The three dogs were affected to different degrees of severity, but all displayed signs of ataxia, generalised muscle tremors, paresis, hypersalivation and disorientation. Temporary blindness occurred in two cases. The three dogs were tested for the presence of the multi-drug resistance 1 gene deletion, which can cause an increased sensitivity to the toxic effects of moxidectin, and were found to be negative. Treatment included gastrointestinal decontamination, intravenous fluid therapy and benzodiazepines to control muscle tremors. All three dogs made a complete recovery within 48 h of ingestion.

Incidence of seizures associated with the use of acepromazine in dogs undergoing myelography.

OBJECTIVE To investigate the frequency of seizures associated with acepromazine administration when used as a premedicant with methadone for dogs undergoing myelography. DESIGN Retrospective clinical case study. SETTING University veterinary teaching hospital. ANIMALS Sixty-six dogs (mixed and pure breeds), aged between 4 months and 15 years, weighing between 3.5-61 kg. All animals were classified as ASA score I or II. INTERVENTIONS Forty-three animals were premedicated with methadone (0.1-0.5 mg/kg) and acepromazine (0.01-0.05 mg/kg) intramuscularly. Twenty-three animals were premedicated with methadone alone (0.1-0.5 mg/kg) intramuscularly. Anesthesia was induced with propofol intravenously and maintained with isoflurane delivered in 100% oxygen. All animals received a balanced isotonic crystalloid solution intravenously at a rate of 10 mL/kg/h. Blood pressure, end-tidal CO(2) , oxygen saturation, respiratory rate, and heart rate were monitored throughout anesthesia. Animals requiring surgery immediately following myelography were excluded from the study. MEASUREMENTS AND MAIN RESULTS The frequency of seizures was 14% (CI: 3.6-24.3%) and 13.0% (CI: 0.7-27%) in dogs that received methadone/acepromazine and methadone alone, respectively. There was no significant difference in the frequency of seizures between dogs receiving methadone/acepromazine or methadone alone (P = 1). Analysis of the association of site of injection of the contrast and the frequency of seizures in dogs receiving methadone/acepromazine showed no significant difference in the frequency of seizures following cervical injection (25%; CI: 0.5-24.5%) or lumbar injection (9.7%; CI: -0.7-20.1%). CONCLUSIONS The administration of acepromazine combined with methadone as a premedicant used with propofol and isoflurane anesthesia did not significantly increase the frequency of seizures following myelography compared to dogs who received methadone alone.

Anaesthetic and surgical management of an intra-tracheal mass in a cat

An 11-year-old, 7 kg male neutered domestic shorthair cat, presented to the University Veterinary Hospital (UVH) for investigation of chronic tachypnoea and dyspnoea. Radiographs, bronchoscopy and computerised tomography (CT) demonstrated an intra-tracheal mass measuring 13 mm×5 mm×6 mm arising from the right wall of the caudal trachea immediately cranial to the carina. Due to size and position, debulking and subsequent cryosurgery were attempted to minimise the amount of tissue removed and prevent recurrence. A combination of anaesthetic techniques was required to allow cryotherapy, with the trachea open whilst maintaining adequate ventilation. This case report demonstrates that cryotherapy in conjunction with anaesthetic planning, can achieve a positive outcome for the cat.

Extradural haematoma secondary to brown snake (Pseudonaja species) envenomation.

A 4-year-old Siberian Husky dog was treated with brown snake antivenom by his regular veterinarian after a witnessed episode of brown snake envenomation. The dog was discharged 5 hours post presentation despite an ongoing coagulopathy. The dog was presented to the emergency centre 2 hours later because the owner believed the dog to be in pain. Initial examination revealed an ambulatory but neurologically normal patient with thoracolumbar pain and laboratory evidence of a coagulopathy. Despite correction of the coagulopathy, the signs progressed to bilateral hind limb paresis after approximately 3 hours of hospitalisation, and continued to deteriorate over the next 56 hours to loss of deep pain perception in the right hind limb. Computed tomography imaging identified the presence of an extradural haematoma which was subsequently removed via a hemilaminectomy. Surgical decompression was successful in treating the spinal compression and the dog recovered with minimal complications. To our knowledge this is the first report of extradural haematoma secondary to coagulopathy induced by brown snake envenomation.

Evaluation of Masimo signal extraction technology pulse oximetry in anaesthetized pregnant sheep

OBJECTIVE Evaluation of the accuracy of Masimo signal extraction technology (SET) pulse oximetry in anaesthetized late gestational pregnant sheep. STUDY DESIGN Prospective experimental study. ANIMALS Seventeen pregnant Merino ewes. METHODS Animals included in study were late gestation ewes undergoing general anaesthesia for Caesarean delivery or foetal surgery in a medical research laboratory. Masimo Radical-7 pulse oximetry (SpO(2) ) measurements were compared to co-oximetry (SaO(2) ) measurements from arterial blood gas analyses. The failure rate of the pulse oximeter was calculated. Accuracy was assessed by Bland & Altmans (2007) limits of agreement method. The effect of mean arterial blood pressure (MAP), perfusion index (PI) and haemoglobin (Hb) concentration on accuracy were assessed by regression analysis. RESULTS Forty arterial blood samples paired with SpO(2) and blood pressure measurements were obtained. SpO(2) ranged from 42 to 99% and SaO(2) from 43.7 to 99.9%. MAP ranged from 24 to 82 mmHg, PI from 0.1 to 1.56 and Hb concentration from 71 to 114 g L(-1) . Masimo pulse oximetry measurements tended to underestimate oxyhaemoglobin saturation compared to co-oximetry with a bias (mean difference) of -2% and precision (standard deviation of the differences) of 6%. Accuracy appeared to decrease when SpO(2) was <75%, however numbers were too small for statistical comparisons. Hb concentration and PI had no significant effect on accuracy, whereas MAP was negatively correlated with SpO(2) bias. CONCLUSIONS AND CLINICAL RELEVANCE Masimo SET pulse oximetry can provide reliable and continuous monitoring of arterial oxyhaemoglobin saturation in anaesthetized pregnant sheep during clinically relevant levels of cardiopulmonary dysfunction. Further work is needed to assess pulse oximeter function during extreme hypotension and hypoxaemia.

Platelet closure time in anesthetized Greyhounds with hemorrhagic shock treated with hydroxyethyl starch 130/0.4 or 0.9% sodium chloride infusions

OBJECTIVE To measure platelet closure time (PCT) in dogs during controlled hemorrhagic shock and after fluid resuscitation with hydroxyethyl starch (HES) 130/0.4 or 0.9% sodium chloride. DESIGN Experimental interventional study. SETTING University veterinary teaching hospital. ANIMALS Eleven healthy Greyhounds. INTERVENTIONS Dogs were anesthetized and had 48 mL/kg of blood removed to induce hemorrhagic shock. Dogs received 20 mL/kg of HES 130/0.4 (n = 6) or 80 mL/kg of 0.9% sodium chloride (NaCl; n = 5) intravenously over 20 minutes. PCT was measured using the Platelet Function Analyzer-100 with collagen and adenosine-diphosphate cartridges at: T0 = 60 minutes after induction of anesthesia prior to hemorrhage, T1 = during hemorrhagic shock, and T2 = 40 minutes after completion of fluid bolus. Packed cell volume and platelet count were concurrently measured. MEASUREMENT AND MAIN RESULTS Hemorrhagic shock did not significantly change PCT, with no difference between T0 and T1. Both the HES 130/0.4 and 0.9% NaCl group had a significantly increased mean PCT at T2 of 91.4 seconds (95% CI 69.3-113.4) and 95.5 seconds (95% CI 78.2-112.8), respectively, compared to T1. The magnitude of change was significantly greater for the 0.9% NaCl group than the HES 130/0.4 group. There was no difference in the magnitude of change in PCV and platelet count between the 2 groups. The PCV and platelet count were >25% and >100,000/μL, respectively, in all dogs, except for dogs in the HES 130/0.4 group at T2 where platelet counts were <100,000/μL. CONCLUSION Controlled hemorrhagic shock in Greyhounds under anesthesia did not cause a significant change in PCT. Both HES 130/0.4 and 0.9% NaCl administration after induction of shock increased PCT. These results do not support that HES 130/0.4 causes relevant platelet dysfunction beyond hemodilution.

The effect of dobutamine and bolus crystalloid fluids on the cardiovascular function of isoflurane anaesthetised horses

REASONS FOR PERFORMING STUDY Cardiac output does not always increase with dobutamine administration in anaesthetised horses and information on peripheral perfusion is lacking. OBJECTIVES To determine the effect of intravenous (i.v.) dobutamine infusion with and without a concurrent 20 mL/kg bodyweight (bwt) bolus of crystalloid fluids on the cardiovascular function of acepromazine premedicated, hypotensive, isoflurane-anaesthetised horses. STUDY DESIGN Randomised, cross-over experiment. METHODS A total of 6 horses aged 5-13 years, weighing 464-578 kg were premedicated with acepromazine 0.02 mg/kg bwt and then sedated with xylazine 0.8 mg/kg bwt i.v. Anaesthesia was induced with ketamine 2.2 mg/kg bwt and diazepam 0.08 mg/kg bwt i.v. and maintained with isoflurane, adjusted to achieve a target mean arterial pressure (MAP) (60 mmHg ± 5%) 60 min post-induction of anaesthesia (T0). One of 2 treatments was then given. In treatment D, dobutamine was initially infused at 0.5 μg/kg bwt/min and adjusted to achieve a target MAP (80 mmHg ± 5%) within 30 min of infusion initiation. In treatment D+F dobutamine was administered as described for treatment D, with 20 mL/kg bwt Hartmanns solution infused i.v. over 20 min. Cardiac index (CI), haemoglobin concentration ([Hb]), arterial oxygen content (CaO2 ), oxygen delivery index (DO2 I) and bilateral femoral arterial blood flow (FBF) were recorded at T0, 30 min following dobutamine initiation (T1) and 15 min following dobutamine cessation (T2). Data were analysed using a mixed-effect linear model (P<0.05 considered significant). RESULTS A significant increase in DO2 I (P = 0.008, T0/T1), CaO2 (P = 0.0002, T0/T1) and [Hb] (P<0.0001, T0/T1) and in CaO2 (P = 0.0005, T1/T2) and [Hb] (P = 0.002,T1/T2) occurred during treatment D. A significant increase in FBF (P = 0.005, upper limb; P = 0.042 lower limb, T0/T1) occurred during treatment D+F. Significant differences between treatments were recorded at T1 ([Hb] P = 0.0001, CaO2 P = 0.0003) and T2 ([Hb] P = 0.013). There was no change in CI during either treatment. CONCLUSIONS The increase in FBF seen with co-administration of fluids and dobutamine may provide a beneficial effect on muscle compared with the use of dobutamine alone.