The Effect of a Subsequent Dose of Dexmedetomidine or Other Sedatives following an Initial Dose of Dexmedetomidine on Sedation and Quality of Recovery in Cats: Part I.

Dexmedetomidine is an a2-agonist commonly used in veterinary practice. Occasionally, the administered dose of dexmedetomidine may result in insufficient sedation, and an additional dose or drug may be required. The sedative effects of seven different drugs administered at subsequent time points after an initial, insufficient dose of dexmedetomidine were evaluated. Seven adult cats participated in this crossover, blind, randomised study. The groups consisted of two consecutive doses of dexmedetomidine (15 + 10 µg/kg) (DD) or a dose of dexmedetomidine (15 µg/kg) followed by either NS 0.9% (DC-control group), tramadol 2 mg/kg (DT), butorphanol 0.2 mg/kg (DBT), buprenorphine 20 µg/kg (DBP), ketamine 2 mg/kg (DK), or midazolam 0.1 mg/kg (DM). Sedation was evaluated using the Grint sedation scale. In all groups, atipamezole was administered at the end of the evaluation, and recovery was assessed using the Lozano and Sams recovery scales. The DC and DM groups exhibited minimal sedative effects. The maximum sedative effect was observed in the DD and DK groups, while sedation in the DD and DK groups was significantly higher compared to the DC group. Recovery in all groups was uneventful, except in the DM group, where it was prolonged and difficult, although no statistically significant difference was detected. Therefore, insufficient sedation with dexmedetomidine can be enhanced by a subsequent dose of dexmedetomidine, ketamine, or butorphanol, whereas the addition of midazolam reduces sedation and prolongs recovery.

The Effect of a Subsequent Dose of Dexmedetomidine or Other Sedatives following an Initial Dose of Dexmedetomidine on Electrolytes, Acid-Base Balance, Creatinine, Glucose, and Cardiac Troponin I in Cats: Part II.

The administered dose of dexmedetomidine may occasionally fail to produce the anticipated sedative effects. Therefore, a subsequent dose or administration of another sedative may enhance sedation; however, patient safety may be affected. The safety of seven different drugs administered at the following time point after an insufficient dose of dexmedetomidine was evaluated in a crossover, blind, experimental study that included six healthy adult cats. All cats received an initial dose of dexmedetomidine and a subsequent dose of either dexmedetomidine (Group DD), NS 0.9% (DC), tramadol (DT), butorphanol (DBT), buprenorphine (DBP), ketamine (DK), or midazolam (DM). Animal safety was assessed using repeated blood gas analysis and measurement of electrolytes, glucose, cardiac troponin I, and creatinine to evaluate cardiac, respiratory, and renal function. The median values of creatinine, cardiac troponin I, pH, partial pressure of carbon dioxide, potassium, and sodium did not change significantly throughout the study. Heart rate was significantly decreased in all groups after administration of the drug combinations, except for in the DK group. Respiratory rate decreased significantly after administration of the initial dose of dexmedetomidine and in the DBP and DM groups. The partial pressure of oxygen, although normal, decreased significantly after the administration of dexmedetomidine, whereas the median concentration of glucose increased significantly following the administration of dexmedetomidine. The results of our study suggest that the drug combinations used did not alter the blood parameters above normal limits, while cardiac and renal function were not compromised. Therefore, a safe level of sedation was achieved. However, the administration of dexmedetomidine reduced the partial pressure of oxygen; thus, oxygen supplementation during sedation may be advantageous. Additionally, the increase in glucose concentration indicates that dexmedetomidine should not be used in cats with hyperglycaemia, whereas the decrease in haematocrit suggests that dexmedetomidine is not recommended in anaemic cats.

Effect of gonadectomy on pain assessment in dogs undergoing orthopaedic stifle surgery.

OBJECTIVE: To compare pain perception between gonadectomized and intact dogs. STUDY DESIGN: Blinded, prospective, cohort study. ANIMALS: A group of 74 client-owned dogs. METHODS: Dogs were divided into four groups: group 1-female/neutered (F/N), group 2-female/intact (F/I), group 3-male/neutered (M/N) and group 4-male/intact (M/I). Premedication consisted of intramuscularly administered acepromazine (0.05 mg kg-1) and morphine (0.2 mg kg-1), and subcutaneously administered carprofen (4 mg kg-1). Anaesthesia was induced with propofol (1 mg kg-1 intravenously and supplementary doses to effect) and maintained with isoflurane in 100% oxygen. Intraoperative analgesia was achieved with fentanyl infusion (0.1 µg kg-1 minute-1). Pain assessments [using the University of Melbourne Pain Scale (UMPS) and an algometer at the incision site (IS), parallel to the incision site (NIS), and on the contralateral healthy limb] were performed preoperatively, and at 1, 2, 4, 6, 9 and 20 hours after extubation. The time-standardised area under the curve (AUCst) for measurements was calculated and compared by performing a one-way multivariate analysis of variance (manova). Statistical significance was set at p < 0.05. RESULTS: Postoperatively, F/N exhibited higher pain than F/I, with estimated marginal means (95% confidence intervals) AUCstISGroup1 909 (672-1146) versus AUCstISGroup2 1385 (1094-1675) (p = 0.014), AUCstNISGroup1 1122 (823-1420) versus AUCstNISGroup2 1668 (1302-2033) (p = 0.024) and AUCstUMPSGroup1 5.30 (4.58-6.02) versus AUCstUMPSGroup2 4.1 (3.2-5.0) (p = 0.041). Similarly, M/N showed higher pain than M/I with AUCstISGroup3 686 (384-987) versus AUCstISGroup4 1107 (871-1345) (p = 0.031) and AUCstNISGroup3 856 (476-1235) versus AUCstNISGroup4 1407 (1109-1706) (p = 0.026), and AUCstUMPSGroup3 6.0 (5.1-6.9) versus AUCstUMPSGroup4 4.4 (3.7-5.2) (p = 0.008). CONCLUSIONS AND CLINICAL RELEVANCE: Gonadectomy affects pain sensitivity in dogs undergoing stifle surgery. Neutering status should be taken into consideration when planning individualized anaesthetic/analgesic protocols.

Effect of anaesthesia on cell-mediated immunity in dogs undergoing mastectomy for mammary cancer.

OBJECTIVE: To investigate if anaesthesia for canine cancer mastectomy further influences host cell-mediated immunity (CMI) promoting cancer progression. STUDY DESIGN: A randomized, controlled, blinded clinical study. ANIMALS: A total of 20 bitches with malignant mammary tumours of clinical stage II or III undergoing the same type of mastectomy (regional mastectomy). METHODS: Dogs were randomly allocated to one of two anaesthetic groups (10 per group). The anaesthetic protocol of group A used minimally immunosuppressive drugs (tramadol, robenacoxib, propofol), whereas that of group B (control) used more immunosuppressive drugs (morphine, fentanyl, thiopental, isoflurane). For each animal, measurements of white blood cells (WBCs), neutrophils and lymphocytes, and flow cytometric assessment of T cells (CD3+), helper T cells (CD4+), cytotoxic T cells (CD8+) and CD5low+ T cells were performed prior to anaesthesia (day 0) and on days 3 and 10 postsurgery. Data were analysed using a General Linear Model for repeated measures and presented as mean ± standard deviation, p ≤ 0.05. RESULTS: In all animals, on day 3, WBCs and neutrophils were significantly increased (p < 0.0005), while flow cytometry revealed significantly decreased relative percentages of T cells (CD3+) (p = 0.003) and their subpopulations CD4+ (p = 0.006), CD8+ (p = 0.029) and CD5low+ (p = 0.031). Specifically, on day 3, the cytotoxic T cells (CD8+) were significantly decreased (p = 0.05) only in group B, whereas the CD4+ (p = 0.006) and CD5low+ (p = 0.008) T cells in group A. The only significant difference between groups was found preoperatively in the CD4+/CD8+ ratio, which was higher in group A (p = 0.006). CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with mammary cancer undergoing regional mastectomy, a significant decrease in components of CMI was observed on day 3 postsurgery in both anaesthetic groups. Some indication, however, for better preserved cellular immunity by less immunosuppressive anaesthetic/analgesic drugs was detected, rendering their use advisable.

Contrast enhanced computed tomography assessment of superficial inguinal lymph node metastasis in canine mammary gland tumors.

Mammary gland neoplasms are predominant in dogs. However, sentinel lymph node (SLN) status assessment criteria have not been established for these cases. In this retrospective, secondary analysis, diagnostic case control study, CT images of 65 superficial inguinal SLNs were obtained before and 1, 3, 5, and 10 min after intravenous administration of contrast agent (iopamidol 370 mgI/mL). The presence and degree of postcontrast enhancement were assessed, by means of the median absolute density value and the maximum absolute density value at any time point in the center and in the periphery of each SLN measured in Hounsfield units (HU), before and after contrast agent administration. These values were compared with histopathological findings postsurgical excision. Receiver operating characteristic analysis was conducted. The absolute density values ranged widely at each time point and within each group of nodes (negative, positive, control group). At all time points, the median density value in the center and in the periphery was significantly higher in metastatic than in non-metastatic SLNs (P ≤ .014). Among the parameters tested, the median absolute density value measured in the periphery of the SLN 3 min after injection showed the highest sensitivity, specificity, and accuracy (AUC) (87.5%, 82.1%, and 92.1% respectively), with a cutoff value of 50.9 HU. The maximum absolute density value at any time point in the center and periphery of the SLNs was also significantly higher in metastatic SLNs compared to non-metastatic (P ≤ .001). With a cutoff value of 59.5 HU, the maximum absolute density value in the periphery of the SLN displayed high sensitivity and specificity (87.5% and 89.3%, respectively). The results of this study support the hypothesis that contrast enhanced CT imaging may aid in the assessment of SLN metastasis in dogs with mammary gland neoplasms.

Transdiaphragmatic Gastrotomy for the Extraction of Distal Esophageal Foreign Bodies in 13 Dogs (1997-2016).

The records of 13 dogs with distal esophageal foreign body obstruction not amenable to endoscopic management that had transdiaphragmatic gastrotomy (TG) for the foreign body extraction were reviewed. West Highland white terriers were over-represented. Mean age of the dogs at presentation was 38.6 mo, and mean duration of clinical signs associated with esophageal foreign bodies was 5.8 days. A TG was performed via an eighth or ninth left intercostal thoracotomy, and clinical results were successful in 12 dogs. In 1 dog, gastrotomy failed to retrieve a foreign body and esophagotomy was performed. Foreign bodies that were removed included 3 fishhooks and 10 animal bones. Postoperatively, all dogs developed esophagitis, 1 dog showed esophageal stricture, and 1 dog died of pyothorax associated with esophageal perforation 1 day postsurgery. Overall, 12 dogs survived and were free of clinical signs after a median follow-up time of 17 mo. TG is an effective surgical technique for the retrieval of distal esophageal foreign bodies.

Comparison of maximum force to failure of 4 thoracostomy tube connecting devices.

OBJECTIVE: To compare the maximum force and displacement to failure of 4 different types of thoracostomy tube connecting devices. STUDY DESIGN: Experimental in vitro study. STUDY POPULATION: Four types of thoracostomy tube connecting devices (n = 10 each). METHODS: Four different connecting device configurations (10 constructs each) were tested by maximum distraction to failure using a dynamometer: (1) CTTWW-a 3-way connector with a male luer slip attached to a thoracostomy tube by a Christmas tree adapter and secured to the tube with 21 gauge orthopedic wire; (2) CTTWRCW-a 3-way connector with a male luer lock with a rotating collar attached to a tube by a Christmas tree adapter and secured to the tube with 21 gauge orthopedic wire; (3) LVSBC-a Lopez valve attached to a tube with its short-barbed connector; and (4) LVLBC-a Lopez valve attached to a tube with its long-barbed connector. RESULTS: The maximum distraction force to failure was significantly greater for CTTWRCW (250.9 N; range 143.7-293.6) than CTTWW (132.9 N; range 84.2-224.1), LVLBC (90.8 N; range 74.0-123.4), and LVSBC (54.6 N; range 39.6-164.2). The median displacement to failure of CTTWRCW (150 mm; range 54-190) was significantly longer than that of CTTWW (34.5 mm; range 22-70), LVLBC (32.5 mm; range 24-57), and LVSBC (16 mm; range 11-69). CONCLUSION: The CTTWRCW group required greater force to create failure and had a longer displacement to failure, making it a more secure choice for connection to thoracostomy tubes.

Upper Airway Injury in Dogs Secondary to Trauma: 10 Dogs (2000-2011).

Ten dogs that presented with trauma-induced upper airway rupture or stenosis were reviewed. Tracheal rupture was seen in seven dogs, tracheal stenosis in one dog, and laryngeal rupture in two dogs. Clinical abnormalities included respiratory distress in five dogs, subcutaneous emphysema in eight, air leakage through the cervical wound in seven, stridor in three dogs, pneumomediastinum in four and pneumothorax in one dog. Reconstruction with simple interrupted sutures was performed in four dogs, tracheal resection and end-to-end anastomosis in five dogs, and one dog was euthanized intraoperatively. Complications were seen in three dogs including aspiration pneumonia in one and vocalization alterations in two dogs.

Spontaneous urethral catheter kinking or knotting in male dogs: four cases.

Four dogs were diagnosed with urethral catheter malfunction. The catheter was kinked in three dogs and knotted in one dog. In two dogs, kinking of the catheter was associated with presence of urethroliths in the perineal urethra. Diagnosis was based on the difficulty encountered retrieving the catheter in all dogs and swelling in the scrotal or perineal area in two dogs. Diagnosis of catheter kinking or knotting was confirmed after catheter retrieval. Catheter removal was achieved in two dogs after traction under anesthesia, whereas scrotal or perineal urethrotomy were used in the other two dogs. No complications associated with urination were reported in any of the dogs after 7 to 12 mo.

Analgesia for small animal thoracic surgery.

Thoracic surgery in small animals is considered a painful procedure, resulting in alterations in pulmonary function and respiratory mechanics. Modifications in surgical approach and technique and selection of the appropriate analgesic protocol may improve outcomes in dogs and cats after thoracic surgery. Systemic administration of opioids and other agents, intercostal and intrapleural blocks, and epidural analgesia are among the most common options for pain management after thoracic surgery in small animals.