COMPUTED TOMOGRAPHY OF NONANESTHETIZED CATS WITH UPPER AIRWAY OBSTRUCTION

COMPUTED TOMOGRAPHY LUNG VOLUME DIFFERS BETWEEN VERTICAL AND INVERTED POSITIONING FOR EGYPTIAN FRUIT BATS (ROUSETTUS AEGYPTIACUS)

This prospective study characterizes the impact of positioning on the pulmonary volume and pulmonary atelectasis in Egyptian fruit bats (Rousettus aegyptiacus). The soft tissue appearance of atelectactic pulmonary parenchyma can obscure or mask pulmonary pathology. Soft tissue within healthy lung parenchyma caused by atelectasis can efface the margins of pathology, such as pulmonary metastasis or pneumonia, due to overlapping attenuation profiles. Pulmonary atelectasis is an unwanted side effect of anesthesia resulting from muscle relaxation and is exacerbated by high (80-100%) inspired oxygen supplementation during general anesthesia. Positioning can help minimize pulmonary atelectasis. Seven R. aegyptiacus received computed tomography imaging in suspended vertical (head-up) and inverted (head-down) positions that generated images in the dorsoventral plane. Vertically positioned bats had a significantly greater lung volume compared to inverted positioning (P = 0.0053). The nondependent portion of the lung apices in the vertically positioned bats had significantly more negative Hounsfield units (i.e. less dense tissue) than the dependent portions of the lung and was also less dense than both portions of the lungs in inverted positioned bats. Although not an intuitive positioning for bats, a vertical orientation generates less pulmonary atelectasis and a greater lung volume compared to bats positioned in a more natural inverted position. Despite physiologic adaptations to hang in an inverted position when not in flight, avoidance of inverted positioning during anesthesia and anesthetic recovery is recommended based on these findings.

Thoracic high resolution CT using the modified VetMousetrap™ device is a feasible method for diagnosing canine idiopathic pulmonary fibrosis in awake West Highland White Terriers

Canine idiopathic pulmonary fibrosis is a chronic, progressive interstitial lung disease particularly prevalent in West Highland White Terriers. In the present prospective pilot study, we evaluated the feasibility of modified VetMousetrap™ device in high resolution CT to detect idiopathic pulmonary fibrosis in West Highland White Terriers. Twelve awake West Highland White Terriers with canine idiopathic pulmonary fibrosis and 24 clinically healthy West Highland White Terriers were scanned using a helical dual slice scanner utilizing VetMousetrap™ device without or with minimal chemical restraint with butorphanol. Three evaluators blindly assessed the images for image quality and the presence of canine idiopathic pulmonary fibrosis related imaging findings such as ground glass opacity and reticular opacities. Additionally, the attenuation of the lung was quantified with ImageJ software using histogram analysis of density over the lung fields. Computed tomography was successfully completed and motion artifact ranked in statistical analysis barely noticeable to mild in all dogs. The agreement between imaging findings and clinical status was very good with overall κ value 0.91 and percentage of agreement of 94%. There was also very good intraobserver (κ_range = 0.79-0.91) and interobserver agreement (κ = 0.94). Moderate to severe ground glass opacity was present in all affected dogs. In the ImageJ analysis, a significant difference in lung attenuation between the study groups was observed. We conclude that modified VetMousetrap™ device is applicable in diagnosing canine idiopathic pulmonary fibrosis in awake West Highland White Terriers avoiding anesthetic risk in these often severely hypoxic patients.

Comparison of Thoracic Radiography and Computed Tomography in Calves with Naturally Occurring Respiratory Disease

Objective

To evaluate the severity and extent of lung disease using thoracic computed radiography (CR) compared to contrast-enhanced multi-detector computed tomography (MDCT) of the thorax in calves with naturally occurring respiratory disease and to evaluate the feasibility and safety of performing contrast-enhanced thoracic multi-detector MDCT examinations in sedated calves. Furthermore, to evaluate if combining CR or MDCT with respiratory scoring factors will improve prediction of the chronicity of pulmonary disease in calves.

Animals

Thirty Jersey heifer calves ranging in age between 25 and 89 days with naturally occurring respiratory disease.

Procedures

All calves were evaluated via thoracic CR and contrast-enhanced MDCT. All calves were euthanized immediately following thoracic MDCT and submitted for necropsy. Imaging and histopathology results were compared with each other.

Results

Thoracic MDCT was superior for evaluation of pneumonia in calves due to the lack of summation in all areas of the lungs. Intravenously administered sedation provided an adequate plane of sedation for acquiring MDCT images of diagnostic quality, without the need for re-scanning. A diagnosis of pneumonia was made with equal rate on both thoracic CR and MDCT. Although mild differences in classification of lung pattern and extent of lung disease were seen when comparing an experienced and a less experienced evaluator, the overall differences were not statistically significant. The best intra- and inter-observer agreement was noted when evaluating the cranioventral aspects of the lungs in either modality. Clinical respiratory scoring is inadequate for diagnosing chronicity of pneumonia in calves with naturally occurring pneumonia.

Conclusion and clinical importance

Both imaging modalities allowed diagnosis of pneumonia in calves. The cranial ventral aspects of the lungs were most commonly affected. Thoracic CR and MDCT provided similar diagnostic effectiveness in diagnosing pneumonia. However, MDCT provided better assessment of subtle details, which may be otherwise obscured due to summation artifact.

Repair of a sliding (type I) hiatal hernia in a cat via herniorrhaphy, esophagoplasty and floppy Nissen fundoplication

Case summary

A 10-month-old domestic shorthair cat was evaluated for severe esophagitis and protracted vomiting and regurgitation secondary to a sliding (type I) hiatal hernia. The hernia and concurrent upper airway obstruction (nasopharyngeal polyp) were diagnosed with a multi-modality approach, including thoracic and abdominal radiographs, abdominal ultrasound, computed tomography and endoscopy. Following unsuccessful attempts at medical management, lower esophageal incompetence was successfully treated by employing a combination of surgical techniques, including herniorrhaphy, esophagopexy and modified (floppy) Nissen fundoplication.

Relevance and novel information

A multi-modality imaging approach was valuable in completely assessing the extent of this cat’s disease. Although an untraditional approach, the authors report herein the first clinical description of the use of combined surgical techniques with the floppy Nissen fundoplication technique (an antireflux procedure) in a cat. This procedure was used as a first-line surgical technique in this cat with severe lower esophageal incompetence, and may be a viable option for cases non-responsive to other therapeutic interventions. Further investigation of this surgical technique is warranted.