Sentinel lymph node mapping by near‐infrared fluorescence imaging and contrast‐enhanced ultrasound in healthy dogs

Sentinel lymph node (SLN) mapping is a valuable and crucial diagnostic procedure in staging malignancies. We compared two non‐invasive techniques, near‐infrared (NIR) fluorescence imaging and contrast‐enhanced ultrasound (CEUS), to identify the SLNs in three superficial anatomical regions in an animal model. Six healthy laboratory dogs were included in a proof‐of‐concept trial. A NIR fluorescent dye (Indocyanine Green) and microbubbles (Sonovue) were consecutively injected subdermally in the Inguinal, axillary and popliteal region to map the SLNs. Transcutaneous NIR fluorescence imaging identified SLNs in 17 out of a total of 18 occasions. CEUS identified SLNs in all regions (18/18). Whereas NIR fluorescence imaging performed better in the visualization of the afferent lymphatic tract, CEUS demonstrated different filling patterns of the SLNs, a feature potentially critical for the concept of SLN mapping in cancer patients. Both NIR fluorescence imaging and CEUS are safe, non‐invasive, practical and accurate methods to perform real‐time transcutaneous SLN mapping with potential in a clinical setting.     

MAGNETIC RESONANCE IMAGING FEATURES OF EMPTY SELLA IN DOGS

In humans, the empty sella is defined as herniation of the subarachnoidal space into the sella turcica with invisible (total empty sella) or reduced (partial empty sella) hypophyseal size. An empty sella can be associated with endocrine disturbances. The purpose of this study was to determine if the empty sella exists in dogs or cats and whether it is associated with endocrinopathy or hydrocephalus. Archived magnetic resonance images of the head of 370 dogs and 77 cats were re-evaluated specifically for the presence or absence of the pituitary gland. Hypophyseal tissue filling more than 50% of the sella was considered normal, between 30% and 50% was defined as partial empty sella and less than 30% was defined as total empty sella. In patients with an empty sella, and in all other imaged dogs of the affected breeds, the ventricle to brain ratio was measured. In patients with an empty sella, the medical record was searched for evidence of endocrinopathy. No cat had an empty sella but 11 dogs (3%) had a small or missing hypophysis. Seven of these dogs had a ventricle to brain ratio greater than 15%. Only small dogs (mean weight of 6.7 kg) were affected. One dog with an empty sella had signs of central hyperadrenocorticism while the other 10 had no sign of endocrinopathy. We conclude that the empty sella exists in dogs but is not generally associated with endocrinopathy.     

Anaesthetic sparing effect of local anaesthesia of the ovarian pedicle during ovariohysterectomy in dogs

ObjectiveTo evaluate the effect of local anaesthesia of the mesovarium on end-tidal isoflurane (Fe′_iso) concentration and vital parameters during canine ovariohysterectomy.Study designProspective, randomized, blinded study.AnimalsTwenty client-owned dogs undergoing elective ovariohysterectomy. Mean age 1.7 (±0.53, SD) years and mean body weight 21 kg (±5.9, SD).MethodsPre-medication was with intravenous acepromazine (0.02 mg kg⁻¹) and methadone (0.1 mg kg⁻¹). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen. One group (n = 10) received local infiltration of the mesovarium with 0.5 mL lidocaine 2% and one group (n = 10) with 0.5 mL NaCl 0.9%. Heart (HR) and respiratory rates (fr), invasive mean arterial blood pressure (MAP) and Fe′_isowere recorded. The Fe′_iso was adjusted according to changes in HR, RR and MAP. Time points used for comparison were T1 (after induction of anaesthesia before surgery), T2 (after lidocaine infiltration of the mesovarium) and T3 (surgical manipulation of the ovaries). Data were analysed using a mixed model for repeated measurement anova and the Tukey adjustment. Results are presented as mean ± SD; p < 0.05 was considered significant.ResultsIn both groups, HR and fr remained stable at the three time points. Mean values ranged from 84 to 94 beats minute⁻¹ and from 10 to 14 breaths minute⁻¹. The Fe′_iso was significantly lower at T3 compared to T1 and mean values ranged from 0.95% to 1.24%. The mean arterial blood pressure was significantly higher at T3 compared to T1 and mean values ranged from 58 to 96 mm Hg. At none of the time points were there significant differences between the two groups for HR, fr, MAP or Fe′_iso.ConclusionNeither an isoflurane sparing effect nor a difference in autonomic response to surgery was demonstrated following local anaesthesia of the mesovarium.Clinical relevanceThere appeared to be minimal benefit from local anaesthesia of the mesovarium during this study.     

A dose‐escalation study of combretastatin A4‐phosphate in healthy dogs

Combretastatin A4 ‐Phosphate (CA4P ) is a vascular disrupting agent revealing promising results in cancer treatments for humans. The aim of this study was to investigate the safety and adverse events of CA4P in healthy dogs as a prerequisite to application of CA4P in dogs with cancer. Ten healthy dogs were included. The effects of escalating doses of CA4P on physical, haematological and biochemical parameters, systolic arterial blood pressure, electrocardiogram, echocardiographic variables and general wellbeing were characterised. Three different doses were tested: 50, 75 and 100 mg m^?2. At all 3 CA4P doses, nausea, abdominal discomfort as well as diarrhoea were observed for several hours following administration. Likewise, a low‐grade neutropenia was observed in all dogs. Doses of 75 and 100 mg m^?2 additionally induced vomiting and elevation of serum cardiac troponine I levels. At 100 mg m^?2, low‐grade hypertension and high‐grade neurotoxicity were also observed. In healthy dogs, doses up to 75 mg m^?2 seem to be well tolerated. The severity of the neurotoxicity observed at 100 mg m^?2, although transient, does not invite to use this dose in canine oncology patients.     

The isoflurane-sparing and clinical effects of a constant rate infusion of remifentanil in dogs

OBJECTIVE: To evaluate the isoflurane-sparing and clinical effects of two constant rate infusions of remifentanil in healthy dogs undergoing orthopaedic surgery. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: Forty-one American Society of Anesthesiologists I-II client-owned dogs (age, 7 months-9 years; body mass 11-59 kg). METHODS: Dogs were randomly assigned to one of three groups and received either: intramuscular (IM) meperidine 2 mg kg(-1) every 2 hours throughout surgery (control group (C); n = 13); remifentanil infused intravenously (IV) at 0.1 microg kg(-1) minute(-1) (low remifentanil group (L); n = 14) or remifentanil infused at 0.25 microg kg(-1) minute(-1) IV (high remifentanil group (H); n = 14). Anaesthesia was induced with thiopental administered to effect and maintained using isoflurane in 100% oxygen. During controlled ventilation when the end-tidal CO(2) was maintained between 4.65 and 5.98 kPa [35-45 mmHg], the end-tidal isoflurane concentration (e'iso%), mean arterial blood pressure (MAP) and heart rate (HR) were measured every 5 minutes. Bradycardia (HR < 40 minute(-1) lasting >5 minutes) was corrected with 0.01 mg kg(-1) IV glycopyrrolate. Data were analysed using the Kruskal-Wallis test with a post-hoc Mann-Whitney U-test and Bonferroni correction. Statistical significance was accepted at < or = 0.05. Data are expressed as mean +/- standard deviation. RESULTS: The e'iso% was reduced in a dose-dependent manner by remifentanil. In C, e'iso% was 1.28 +/-0.13 and was significantly different from L (0.78 +/- 0.17, p < 0.001) and H (0.65 +/- 0.16, p < 0.001). HR was significantly different between groups (p < 0.001). There were no significant differences in MAP between groups. Glycopyrrolate was required in two, three and six dogs in the C, L and H groups respectively. CONCLUSIONS: Remifentanil infusion reduced the isoflurane concentration required for surgical anaesthesia during orthopaedic surgery. CLINICAL RELEVANCE: Remifentanil infusions may be a useful additive to isoflurane anaesthesia in healthy dogs.     

The effect of topical treatment on esophageal pH during acid reflux in dogs

OBJECTIVE: To determine the effect of suction, lavage and instillation of sodium bicarbonate solution on esophageal pH during acidic gastro-esophageal reflux (GER) in anesthetized dogs. STUDY DESIGN: Prospective, clinical trial. ANIMALS: Ten healthy dogs, 4.8 +/- 2.4 years old, and weighing 37.1 +/- 7.9 kg. METHODS: Dogs were admitted to the study if they were under general anesthesia and regurgitation occurred. A sensor-tipped catheter was used to measure esophageal pH. On study entry the esophagus was suctioned. After an interval of at least 5 minutes, if the esophageal pH was still less than 4 the esophagus was lavaged with tap water and again suctioned. In 6 dogs 20 mL of dilute bicarbonate solution was instilled into the esophageal lumen. RESULTS: Suctioning fluid from the esophagus did not change the pH significantly. Lavage with tap water caused the pH to increase above 4 in four dogs, with the average pH increasing from 1.2 +/- 0.5 to 3.5 +/- 4.9. In all dogs where dilute bicarbonate solution was instilled, esophageal pH increased to above 6 for up to 180 (mean +/- SD, 89 +/- 81) minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Suctioning refluxate from the esophagus does not change the pH of the esophageal lumen. Instillation of a small volume of bicarbonate solution predictably increased the pH above 4 following an episode of acidic GER. Care must be taken that fluid is instilled into the lumen of the esophagus, and not into the trachea.     

Pre-anesthetic meperidine: associated vomiting and gastroesophageal reflux during the subsequent anesthetic in dogs

OBJECTIVE: To determine the effect of meperidine administered prior to anesthesia on the incidence of vomiting before, and gastroesophageal reflux (GER) and regurgitation during, the subsequent period of anesthesia in dogs. STUDY DESIGN: Randomized, controlled trial. ANIMALS: A total of 60 healthy dogs, 4.3 +/- 2.3 years old, and weighing 35.5 +/- 13.1 kg. METHODS: Dogs were admitted to the study if they were healthy, had no history of vomiting, and were scheduled to undergo elective orthopedic surgery. The anesthetic protocol used was standardized to include thiopental and isoflurane in oxygen. Dogs were randomly selected to receive one of the following pre-medications: morphine (0.66 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM), meperidine (8.8 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM) or meperidine alone (8.8 mg kg(-1) IM). A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastro-esophageal reflux was judged to have occurred if there was a decrease in esophageal pH below four or an increase above 7.5. RESULTS: No dogs vomited after the administration of meperidine, but 50% of dogs vomited after the administration of morphine. When compared with morphine, treatment with meperidine alone or combined with acepromazine before anesthesia was associated with a 55% and 27% reduction in absolute risk of developing GER, respectively. Dogs receiving meperidine alone were significantly less sedate than other dogs in the study, and required more thiopental to induce anesthesia. Arterial blood pressure and heart rate were not significantly different between groups at the start of the measurement period. Cutaneous erythema and swelling were evident in four dogs receiving meperidine. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of meperidine to healthy dogs prior to anesthesia was not associated with vomiting and tended to reduce the occurrence of GER, but produced less sedation when compared with morphine. Meperidine is not a useful addition to the anesthetic protocol if prevention of GER is desired.