Influence of fentanyl, medetomidine-fentanyl or acepromazine-fentanyl premedication on oesophageal and rectal temperature in dogs under anaesthesia.

OBJECTIVE: To compare changes in oesophageal (T-Oeso) and rectal (T-Rec) temperature in dogs during general anaesthesia and premedicated with fentanyl, medetomidine-fentanyl or acepromazine-fentanyl. STUDY DESIGN: Prospective, randomized, blind clinical study. ANIMALS: A total of 120 healthy dogs, aged 2-10 years and weighing 5-20 kg. METHODS: Dogs were randomly allocated to one of three groups. Animals of F group were premedicated with fentanyl (0.01 mg kg-1), MF group with medetomidine (0.005 mg kg-1) and fentanyl (0.01 mg kg-1) and AF group with acepromazine (0.01 mg kg-1) and fentanyl (0.01 mg kg-1). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen-air mixture. Fentanyl was administered continuously (0.01 mg kg-1 hour-1). The T-Oeso, T-Rec and ambient temperatures were recorded after induction (T0) and subsequently at 10 minute intervals for 60 minutes (T10-T60). Data were analysed using anova or their non-parametric equivalents (p < 0.05). RESULTS: Median T-Oeso was significantly higher in MF group between T0-T20 compared with other groups. Median T-Oeso significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T30), 37.1 °C (T40), 36.9 °C (T50) and 36.6 °C (T60), in MF group from 38.3 °C (T0) to 37.7 °C (T30), 37.5 °C (T40), 37.2 °C (T50) and 37.1 °C (T60) and in AF group from 37.7 °C (T0) to 37.3 °C (T40), 37.2 °C (T50) and 37.1 °C (T60). The T-Rec significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T40), 37.2 °C (T50) and 36.9 °C (T60), in MF group from 38.3 °C (T0) to 37.5 °C (T50) and 37.4 °C (T60) and in AF group from 38.2 °C (T0) to 37.6 °C (T40), 37.5 °C (T50) and 37.4 °C (T60). CONCLUSIONS AND CLINICAL RELEVANCE: Premedication with fentanyl, medetomidine-fentanyl or acepromazine-fentanyl in the doses used decreased the T-Oeso and T-Rec. The T-Oeso at the beginning of anaesthesia was higher after premedication with medetomidine-fentanyl. However, this difference was not clinically significant.

Influence of Methadone on Intraocular Pressure, Pupil Size, and Aqueous Tear Production in Healthy Dogs.

Intraocular pressure (IOP), pupil size (PS), and tear production are variables important in maintaining eye homeostasis. The purpose of this study was to determine the effects of methadone on IOP, PS, and tear production measured by Schirmer I tear test (STT-I) in healthy nonpainful dogs. A prospective, randomized, "double-blind" clinical study was performed. A total of 40 healthy conscious client-owned dogs were included in the study. Dogs were allocated randomly to 1 of 3 groups and given intravenous methadone 0.3 mg/kg (Met-IV, n = 15), intramuscular methadone 0.3 mg/kg (Met-IM, n = 15), or saline 0.3 mL/kg (SAL, n = 10). IOP, PS, STT-I, heart rate (HR), and mean arterial pressure (MAP) were measured prior to (baseline) and at 2, 5, 10, 20, and 30 minutes after drug administration. Data were analyzed using 1-way and 2-way repeated measures ANOVA or their nonparametric equivalents (P < .05). No significant differences in IOP and PS within or between the groups were detected. In the Met-IV group, the STT-I decreased significantly after 30 minutes (P = .025), however, the values remained within the physiological ranges. In Met-IV group, HR decreased significantly at 5, 10, 20, and 30 minutes, respectively. No other significant differences were observed. Methadone administered at a dose of 0.3 mg/kg intravenously or intramuscularly seems to cause within 30 minutes no clinically important effect on IOP, PS, and STT-I in healthy conscious nonpainful dogs without ocular abnormalities.

Influence of anaesthetics on aqueous tear production in dogs: a systematic review.

OBJECTIVE: The aim of this systematic review is to summarize outcomes of studies focused on the effects of opioids, injectable sedative and anaesthetic drugs and inhalant anaesthetics on tear production in dogs. This manuscript complements the systematic review describing the effect of anaesthetics on intraocular pressure in dogs (Pierce-Tomlin et al. 2020). Databases used A detailed search of scientific references has been performed. PubMed, Web of Science, Science Direct and Google Scholar databases were used to search for sources using free text terms 'Dog' or 'Canine', 'Anaesthesia' or 'Anaesthetic' or 'Sedative' or 'Opioid' or the name of used opioids, sedative and anaesthetic drugs and 'Tear' or 'Schirmer' or 'Lacrimation'. The time frame searched was from 1960 to October 2021. Any published manuscripts that were concerned with sedative or anaesthetic drugs administered systemically in the dog and tear production were evaluated. CONCLUSIONS: Low doses of α2-adrenoceptor agonists, neuroleptics, benzodiazepines, opioids, propofol or alfaxalone administered alone have no clinically significant effect on aqueous tear production in healthy dogs measured by the Schirmer tear test I (STT-I). Intramuscular injection of ketamine increases STT-I values. Higher doses of α2-adrenoceptor agonists and combinations of anaesthetics, including inhaled anaesthetics, always clinically significantly decrease tear production.

Influence of Fentanyl, Ketamine, and Lidocaine on Tear Production in Healthy Conscious Dogs.

Tear production is an important factor in maintaining proper function of the cornea and conjunctiva. The purpose of this study was to determine the effects of bolus followed by infusion of fentanyl, lidocaine, and ketamine on tear production as measured by the Schirmer I Tear Test (STT-I) in dogs. A prospective, randomized, "double-blind" study was performed. A total of 55 healthy conscious client-owned dogs were included in the study. Dogs were randomly allocated to one of four groups and given intravenous fentanyl 0.005 mg kg-1 followed by 0.005 mg kg-1 hour-1 (FEN-group), ketamine 0.6 mg kg-1 followed by 0.6 mg kg-1 hour-1 (KET-group), lidocaine 1 mg kg-1 followed by 1 mg kg-1 hour-1 (LID-group), or saline 0.3 mL kg-1 followed by 2 mL kg-1 hour-1 (SAL-group). The STT-I was performed prior to (baseline) and again 30 minutes (T30) after initiation of drug administration. Data were expressed as the median (minimum - maximum) and analyzed by Wilcoxon and Steel-Dwass tests (P < .05). The STT-I values increased little but were statistically significant in the KET-group from 18 (14-23) to 19 (14-25) (P = .039) and in the LID-group from 21 (14-25) to 20 (17-29) (P = .027). At 30 minutes, STT-I values were significantly higher in LID-group 20 (17-29) than in FEN-group 18 (12-22) (P = .006). Fentanyl, ketamine, and lidocaine administered at the studied doses as a bolus and then followed by an infusion within 30 minutes in healthy conscious dogs demonstrated a clinically insignificant effect on tear production as measured by STT-I.

Early Analgesic Efficacy of Morphine, Butorphanol, Lidocaine, Bupivacaine or Carprofen After Periodontal Treatment in Dogs.

The early effectiveness of 5 analgesics was investigated after periodontal treatment. Dogs were assigned to 6 groups (n = 14 each). A prospective, randomized and blinded clinical study was performed. Before anesthesia was induced, butorphanol, morphine, carprofen and saline were administered. After induction, a maxillary and mandibular block was performed with lidocaine or bupivacaine. Painful periodontal therapies were performed. Two hours after the administration of analgesics and after anesthesia reversal, pain was scored using the Visual Analog Scale for pain (VAS) and the modified University of Melbourne Pain Score (UMPS). Blood glucose and cortisol levels were measured prior to analgesic administration and again 2 hours later. Rescue analgesia was provided when the VAS exceeded 50 mm or the UMPS exceeded 14 points. Rescue analgesia was required in one patient in the morphine group and one in the carprofen group. The VAS values were significantly lower in the butorphanol group compared to those of the saline group and in the bupivacaine group vs. those in the saline and lidocaine groups. Significantly lower UMPS values were obtained in the bupivacaine group compared to those in the saline, butorphanol and lidocaine groups and in the carprofen group vs. those in the saline and lidocaine groups. Significantly higher serum cortisol values were found in the lidocaine group compared to those in the saline, bupivacaine and carprofen groups. Administration of carprofen or the use of nerve blocks with bupivacaine improved analgesia after periodontal treatment more than did butorphanol, morphine or nerve blocks using lidocaine.

Nanotechnology and mesenchymal stem cells with chondrocytes in prevention of partial growth plate arrest in pigs.

INTRODUCTION: This study describes the results achieved using a combination of allogeneic mesenchymal stem cells (MSCs) with chondrocytes (CHC) and a new scaffold consisting of type-I collagen and chitosan nanofibers in the prevention of partial growth plate arrest after iatrogenic injury in pigs. MATERIAL AND METHODS: The miniature pig was selected as an experimental model to compare the results in the left femoral bones (MSCs and CHC in scaffold transplantation into the iatrogenic partial distal growth plate defect) and right femoral bones (scaffold alone transplantation). The experimental group consisted of 10 animals. Bone marrow from os ilium as the source of MSCs was used. A porous cylinder consisting of 0.5% by weight type-I collagen and 30% by weight chitosan, was the optimal choice. The length of the bone and angular deformity of distal femur after the healing period was measured and the quality and structure of the newly formed cartilage was histologically examined. RESULTS: Transplantation of the composite scaffold in combination with MSCs and chondrocytes led to the prevention of growth disorder and angular deformity in the distal epiphysis of the left femur. Compared to the right (control) femur, tissue similar to hyaline cartilage with signs of columnar organization typical of the growth plate occurred in most cases. CONCLUSIONS: The promising results of this study reveal the new and effective means for the prevention of bone bridge formation after growth plate injury.

Effect of medetomidine-butorphanol and dexmedetomidine-butorphanol combinations on intraocular pressure in healthy dogs.

OBJECTIVE: To assess the effects of intravenous (IV) medetomidine-butorphanol and IV dexmedetomidine-butorphanol on intraocular pressure (IOP). STUDY DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: Forty healthy dogs. Mean ± SD body mass 37.6 ± 6.6 kg and age 1.9 ± 1.3 years. METHODS: Dogs were allocated randomly to receive an IV combination of dexmedetomidine, 0.3 mg m(-2), combined with butorphanol, 6 mg m(-2), (group DEX) or medetomidine 0.3 mg m(-2), combined with butorphanol 6 mg m(-2), (group MED). IOP and pulse (PR) and respiratory (f(R) ) rates were measured prior to (baseline) and at 10 (T10), 20 (T20), 30 (T30) and 40 (T40) minutes after drug administration. Oxygen saturation of hemoglobin (SpO(2)) was monitored following sedation. Data were analyzed by anova followed by Dunnett's tests for multiple comparisons. Changes were considered significant when p < 0.05. RESULTS: Following drug administration, PR and f(R) were decreased significantly at all time points but did not differ significantly between groups. Baseline IOP in mmHg was 14 ± 2 for DEX and 13 ± 2 for MED. With both treatments, at T10, IOP increased significantly (p < 0.001), reaching 20 ± 3 and 17 ± 2 for DEX and MED respectively. This value for DEX was significantly higher than for MED. There were no significant differences in IOP values between groups at any other time points. At T30 and T40, IOP in both groups was below baseline (DEX, 12 ± 2 and 11 ± 2: MED 12 ± 2 and 11 ± 2) and this was statistically significant, for DEX. CONCLUSIONS AND CLINICAL RELEVANCE: At the documented doses, both sedative combinations induced a transient increase and subsequent decrease of IOP relative to baseline, which must be taken into consideration when planning sedation of animals in which marked changes in IOP would be undesirable.

Novel biodegradable polydioxanone stents in a rabbit airway model.

OBJECTIVE: This study was undertaken to evaluate safety and biocompatibility of a novel biodegradable polydioxanone stent in a rabbit tracheal model. Metallic and silicone stents represent standard therapeutic approaches for hollow organ stenosis, although complications have been reported repeatedly. Biodegradable stents could reduce the risks associated with this procedure while still achieving the purpose of maintaining lumen patency. METHODS: A commercially available polydioxanone suture strand with a long safety record was used to manufacture the self-expanding stents. The polydioxanone stents were then implanted bronchoscopically and under fluoroscopic guidance into the tracheas of white rabbits (N = 25). Periodic clinical examination was performed. Histopathologic examination concluded the study for the 5 experimental groups at 3, 4, 5, 10, and 15 weeks after implantation. RESULTS: There were no unexpected deaths and no stent displacements during the study. The animals remained in good condition, without stent debris expectoration. Macroscopic examination revealed that the tracheal lumen stayed open. Histologic examination showed that tracheal damage score was highest 5 weeks after stenting, including in-stent necrosis of the epithelium. Stent degradation was complete with no remnants after 10 weeks, leaving the trachea completely healed at 15 weeks after implantation. CONCLUSIONS: This animal airway model has demonstrated acceptable safety and biocompatibility of this novel biodegradable polydioxanone stent. We suggest that polydioxanone stenting be used for further clinical studies for cases in which complete stent degradation after temporary airway treatment is desirable.

Experimental model of myocardial infarction: Histopathology and reperfusion damage revisited.

The goal of this pilot study was to create an experimental model of myocardial infarction (for subsequent evaluation of the effectiveness of an alternative way of stem cell application - intracoronary cell infusion in the management of acute myocardial infarction). Four experimental animals, female pigs weighing between 30 and 40 kg, were used in the initial phase of this study to create an experimental model of acute myocardial infarction. An experimental myocardial infarction was performed via occlusion of the interventricular arm of the left coronary artery for 90 min. The hearts were examined 1 h, 3 days, 5 days, and 7 days after the procedure. Macroscopically, red infarction characteristic of reperfusion was found. Microscopically, the healing process with granulation tissue production/collagen deposition was remarkably accelerated compared to literature data. Repair processes in reperfused experimental myocardial infarction and/or reperfused autopsy specimens should not be evaluated on the basis of literature data only. Large collections of extracellular calcium were present. This phenomenon is not well described in the literature and probably has the potential for significantly interfering with the repair process. The histopathology of reperfused acute myoardial infarction deserves to be studied in further investigations.

Direct comparison of enoxaparin and nadroparin in a rabbit model of arterial thrombosis prevention.

INTRODUCTION: The aim of the study was to evaluate and compare the efficacy of standard unfractionated heparin (UFH) and low-molecular weight heparins (LMWH's). MATERIALS AND METHODS: We modified a previously published rabbit model of arterial thrombosis prevention [1,2] to compare unfractionated heparin and two different doses of two low-molecular weight heparin fragments--nadroparin and enoxaparin. Thrombosis in the distal aorta was triggered by vessel wall injury and critical stenosis. Blood flow in the damaged arterial segment was monitored by a flow probe placed distal to the constrictor. The primary endpoints of the study were: (1) cumulative flow, (2) time to occlusion and (3) residual clot weight. Thirty six animals were split into 6 groups with six animals in each group. Control groups were given saline or heparin and four more groups were used to compare LMWH's at 2 different doses. RESULTS: In our study, all treatments were superior to the saline control group (alpha

Incidence of seizures associated with iopamidol or iomeprol myelography in dogs with intervertebral disk disease: 161 cases (2000-2002).

OBJECTIVE: To compare the incidence of seizures in dogs with intervertebral disk disease after iopamidol or iomeprol myelography, and to assess whether the incidence of seizures differed between the 2 agents when severity of neurological deficits, location of cord compression, duration of anesthesia, site of myelogram, volume of contrast, and concentration of contrast were evaluated. DESIGN: Retrospective study. SETTING: Veterinary teaching hospital. ANIMALS: One hundred and sixty-one client-owned dogs with intervertebral disk disease. INTERVENTIONS: Subarachnoid injection of contrast medium. MEASUREMENTS AND MAIN RESULTS: One hundred and sixty-one dogs with intervertebral disk disease were subjected to myelography using iopamidol (n=74) or iomeprol (n=87). Cranial myelography was performed in 31 dogs, caudal myelography in 125 and both cranial and caudal myelography in 5. Seizures occurred in 23 of 161 (14%) dogs. There was no significant difference overall between iopamidol and iomeprol myelography. However, in dogs with thoracolumbar disk extrusion and paraplegia, seizures occurred more frequently after caudal myelography using iopamidol compared with iomeprol. CONCLUSIONS: Both iomeprol and iopamidol are suitable for myelography in dogs. Iomeprol is recommended for caudal myelography in paraplegic dogs with thoracolumbar disk extrusion due to the higher incidence of seizures in this group when iopamidol was used.

Intracoronary delivery of bone marrow cells to the acutely infarcted myocardium. Optimization of the delivery technique.

OBJECTIVES: Intracoronary cell transplantation during catheter balloon inflations may be associated with adverse events. We studied the effectiveness of an alternative transplantation technique--intracoronary cell infusion. METHODS: Fourteen pigs, which had survived acute myocardial infarction, were randomized into 2 treatment groups and 2 controls. Three days after infarction, 12 pigs underwent allogeneic intracoronary mononuclear bone marrow cell transplantation using either the standard technique (short-term cell injections during repeat balloon inflations, technique A, n = 6) or continuous intracoronary cell infusion without balloon inflations (technique B, n = 6). Implanted cells were stained with fluorescent dye. After transplantation, the pigs were euthanized and myocardial samples were analyzed by fluorescent microscopy. RESULTS: The mean numbers of fluorescently labeled bone marrow cells in the infarction border zone, in the infarction mid-area and in the center of myocardial infarction were 84, 72 and 55 using technique A, and 29, 57 and 46 using technique B, respectively. The mean cell retention in the infarction border zone of 84 cells for technique A and 29 cells for technique B differed significantly (p = 0.034, two-tailed t test). CONCLUSION: The continuous intracoronary cell infusion technique is a less efficient cell delivery technique as compared with the standard technique using repeat intracoronary balloon inflations.