Andrea Schwarz

Comparison of a new metamizole formulation and carprofen for extended post-operative analgesia in dogs undergoing ovariohysterectomy

A newly developed slow-release tablet formulation of metamizole was compared with carprofen for post-operative analgesia in dogs undergoing ovariohysterectomy. Twenty-three dogs were randomly assigned to one of two groups, and administered 50 mg/kg metamizole PO (Group M) or 4 mg/kg carprofen PO (Group C) 1 h before anaesthetic induction and 24 and 48 h later. Anaesthesia was induced with propofol and maintained with isoflurane and fentanyl, after premedication with 0.005 mg/kg medetomidine and 0.3 mg/kg methadone IM. A blinded observer assessed post-operative sedation, and analgesia using a visual analogue scale, a dynamic interactive visual analogue scale, the Glasgow composite pain scale (GCPS), and a mechanical nociceptive threshold device (T = 0.5, 1, 2, 4, 8, 12, 18, 21, 24, 36, 45, 60 and 70 h after surgery). Rescue methadone was administered if the GCPS was >6/24 in ambulatory dogs, or >5/20 in non-ambulatory dogs. Plasma concentrations of test drugs were quantified. The dose range for metamizole was 39-56 mg/kg. At T = 0.5 h sedation scores were significantly higher in Group C and GCPS scores were significantly higher in Group M. Three dogs required rescue methadone (Group M, n = 1; Group C, n = 2). Vomiting occurred post-operatively in 45% of dogs in Group M. Carprofen and metamizole were both well absorbed; peak concentrations occurred within 4-24 h, and 4-16 h for carprofen and metamizole, respectively. Both drugs provided adequate analgesia of similar duration. No side effects were observed with carprofen while vomiting was frequent following administration of metamizole.

Novel avulsion pattern of the left principal bronchus with involvement of the carina and caudal thoracic trachea in a cat

A 2-year-old, 4.5 kg, neutered male domestic shorthair cat was presented to the emergency service with dyspnoea, anorexia and apathetic behaviour. Thoracic radiographs showed typical signs for a thoracic trauma and a tracheal lesion in the region of the carina, consistent with pseudoairway formation. Computed tomography (CT) was performed in the conscious cat to avoid aggravation of air leakage associated with ventilation. The additional CT findings were consistent with a novel pattern of a traumatic avulsion of the left principal bronchus expanding into the carina and caudal thoracic trachea. Despite the complex avulsion pattern, successful treatment was achieved surgically by performing an end-to-end anastomosis via a fifth right intercostal lateral thoracotomy. The cat was ventilated with a feeding tube and jet ventilation throughout. The cat showed excellent recovery 6 months after surgery.

Evaluation of accuracy of invasive and non-invasive blood pressure monitoring in relation to carotid artery pressure in anaesthetised ponies

Invasive blood pressure measurement (IBP) using peripheral arteries is a commonly used technique in equine anaesthesia, although the accuracy has not been demonstrated. Non-invasive blood pressure monitoring (NIBP) may be indicated for field anesthesia, short procedures and foal anaesthesia. In the present report, the agreement of various IBP and NIBP measuring sites compared to carotid artery pressure was tested in anaesthetised experimental ponies. Six ponies were anaesthetised in lateral recumbency with sevoflurane and received either saline or dexmedetomidine boli followed by constant rate infusion (CRI). Invasive blood pressure measurements were obtained simultaneously from the carotid, facial and metatarsal arteries. NIBP measurements over both median arteries, metatarsal and middle coccygeal arteries were performed in random order. All blood pressure readings obtained were compared to carotid pressure by Bland-Altman analysis. Non-invasive blood pressure measurements had larger bias and poorer limits of agreement compared to IBP measurements. NIBP measurement from the coccygeal artery had the best repeatability and best limits of agreement of all NIBP positions and was not affected by the use of dexmedetomidine. The facial artery had smaller limits of agreement with dexmedetomidine treatment. There was no difference between the facial and metatarsal arteries during dexmedetomidine treatment in MAP and DAP. Systolic arterial pressures from the metatarsal artery showed larger bias and larger limits of agreement compared to facial artery. In conclusion, NIBP measurement from the tail artery is a reliable alternative to direct arterial blood pressure measurement. Both the metatarsal and facial arteries have acceptable agreement with carotid artery pressure so the choice can be based on the logistics of the procedure.

Perfusion- and diffusion-weighted magnetic resonance imaging of the liver of healthy dogs

OBJECTIVE To describe the perfusion and diffusion characteristics of the liver in healthy dogs as determined by morphological, perfusion-weighted, and diffusion-weighted MRI. ANIMALS 11 healthy adult Beagles. PROCEDURES Each dog was anesthetized and underwent morphological, perfusion-weighted, and diffusion-weighted MRI of the cranial aspect of the abdomen. On the MRI images, a region of interest (ROI) was established for each of 6 structures (aorta, caudal vena cava, portal vein, hepatic parenchyma, splenic parenchyma, and skeletal [epaxial] muscle). The signal intensity was determined, and a time-intensity curve was generated for each ROI. The apparent diffusion coefficient (ADC) was calculated for the hepatic and splenic parenchyma in diffusion-weighted MRI images, and the normalized ADC for the liver was calculated as the ratio of the ADC for the hepatic parenchyma to the ADC for the splenic parenchyma. Dogs also underwent abdominal ultrasonography, and ultrasound-guided fine-needle aspirate samples and biopsy specimens were obtained from the liver for cytologic and histologic examination. RESULTS Cytologic and histologic results suggested that the liver was clinically normal in all dogs. Perfusion-weighted MRI parameters varied among the 6 ROIs. The mean ± SD ADC of the hepatic parenchyma was 0.84 × 10(-3) mm(2)/s ± 0.17 × 10(-3) mm(2)/s, and the mean normalized ADC for the liver was 1.8 ± 0.4. CONCLUSIONS AND CLINICAL RELEVANCE Results provided preliminary baseline information about the diffusion and perfusion characteristics of the liver in healthy dogs. Additional studies on dogs of various breeds with and without hepatopathies are necessary to validate and refine these findings.

Non-invasive quantification of hepatic fat content in healthy dogs by using proton magnetic resonance spectroscopy and dual gradient echo magnetic resonance imaging

The objective of the present study was to describe two non-invasive methods for fat quantification in normal canine liver by using magnetic resonance imaging (MRI) and spectroscopy. Eleven adult beagle dogs were anesthetized and underwent magnetic resonance examination of the cranial abdomen by performing morphologic, modified Dixon (mDixon) dual gradient echo sequence, and proton magnetic resonance spectroscopy (1H MRS) imaging. In addition, ultrasonographic liver examination was performed, fine-needle liver aspirates and liver biopsies were obtained, and hepatic triglyceride content was assayed. Ultrasonographic, cytologic, and histologic examination results were unremarkable in all cases. The median hepatic fat fraction calculated was 2.1% (range, 1.3%–5.5%) using mDixon, 0.3% (range, 0.1%–1.0%) using 1H MRS, and 1.6% (range 1.0%–2.5%) based on triglyceride content. The hepatic fat fractions calculated using mDixon and 1H MRS imaging were highly correlated to that based on triglyceride content. A weak correlation between mDixon and 1H MRS imaging was detected. The results show that hepatic fat content can be estimated using non-invasive techniques (mDixon or 1H MRS) in healthy dogs. Further studies are warranted to evaluate the use of these techniques in dogs with varying hepatic fat content and different hepatic disorders.