A COMPUTED TOMOGRAPHIC STUDY OF VOLUME AND X-RAY ATTENUATION OF THE LUNGS OF BEAGLES IN VARIOUS BODY POSITIONS

The influence of body position on volume and x-ray attenuation of the lungs of three Beagles was investigated with computed tomography. In left and right lateral recumbency, the dependent lung had decreased volume and increased x-ray attenuation compared with ventral recumbency. Volume and x-ray attenuation of the nondependent lung, however, were unchanged. In dorsal recumbency, there was a vertical gradient of x-ray attenuation being increased dorsally and decreased ventrally compared with ventral recumbency where regional differences in x-ray attenuation were not found. Results indicate a risk of overlooking a mass in the dependent pulmonary parenchyma of dogs in lateral and dorsal recumbency. Regional differences in x-ray attenuation of the lungs of dogs can be avoided if the radiographs are obtained with the dog in ventral recumbency.     

Bronchoalveolar lavage fluid findings in the atelectatic regions of anesthetized horses

To evaluate the effects of compression atelectasis on the composition of pulmonary secretions in anesthetized horses, cytological and biochemical examinations were performed on bronchoalveolar lavage (BAL) fluids obtained from both dependent and independent lung regions. Six horses were anesthetized with isoflurane and oxygen for 120 min, and were positioned in right lateral recumbency. Percentage of neutrophils and total protein concentration in BAL fluids significantly increased at the end of anesthesia, and total phosphorous concentration significantly decreased at 72 hr after anesthesia in dependent lung. Such changes were not observed within 168 hr after anesthesia. These findings suggest that the effects of compression atelectasis on the composition of pulmonary secretions may be eliminated within 168 hr after anesthesia.     

THE CANINE LATERAL THORACIC RADIOGRAPH

Selected structures seen on right and left lateral thoracic radiographs of 12 dogs were evaluated for differences in position, size, and shape. The size and position of the cardiac silhouette were different when thoracic radiographs made in left and right lateral recumbency were compared. These changes were, however, considered insignificant. The position of the right cranial lobe bronchus relative to the left varied in right lateral recumbency and left lateral recumbency. The right cranial lung lobe was better aerated when dogs were positioned in left lateral recumbency.
Lesions seen in the caudal portion of the left cranial lung lobe or the right middle lobe were masked when the affected lobe was dependent, and enhanced when the affected lung lobe was non-dependent. It is believed that this difference occurred due to compression of the dependent lung with greater aeration of the non-dependent lung.     

Evaluation of six-lead electrocardiograms obtained from dogs in a sitting position or sternal recumbency

OBJECTIVE: To compare 6-lead ECG traces in clinically normal conscious dogs in a sitting position and sternal recumbency to that of right lateral recumbency. ANIMALS: 31 healthy dogs with no history of cardiac disease. PROCEDURE: Six-lead ECGs were recorded for dogs in right lateral recumbency, a sitting position, and sternal recumbency. Q-, R-, and S-wave amplitudes as well as QRS-complex duration were measured in all leads. Additionally, P-wave amplitude and duration, PR interval, ST-segment elevation or depression, and OT interval were measured in lead II. RESULTS: Compared with measurements in right lateral recumbency, the sitting position resulted in increased Q-wave amplitude (lead III), increased R-wave amplitude (leads I and aVL), decreased R-wave amplitude (leads III and aVF), increased S-wave amplitude (lead aVR), decreased S-wave amplitude (lead aVL), increased P-wave amplitude (lead II), and a leftward shift in the mean electrical axis. Compared with measurements in right lateral recumbency, sternal recumbency resulted in decreased Q-wave amplitude (leads I, II, and aVF), increased R-wave amplitude (leads 11, III, and aVF), decreased R-wave amplitude (lead aVR), increased S-wave amplitude (lead aVR), increased P-wave amplitude (lead II), and decreased ST-segment depression (lead II). Compared with right lateral recumbency, the sitting position or sternal recumbency did not result in significant differences in PR interval, QT interval, or QRS-complex duration. CONCLUSIONS AND CLINICAL RELEVANCE: Significant changes are found in ECG measurements in the sitting position and sternal recumbency, compared with right lateral recumbency. In dogs, many ECG reference range values for right lateral recumbency are not valid for ECGs obtained in the sitting position or sternal recumbency.     

Effect of body position on cranial migration of epidurally injected methylene blue in recumbent dogs

OBJECTIVE: To determine the relationship between different body positions during recumbency on the cranial migration of epidurally injected methylene blue in canine cadavers. SAMPLE POPULATION: 21 fresh cadavers of clinically normal adult female mixed-breed dogs. PROCEDURE: Dogs were randomly assigned to the following 3 groups: dogs remaining in right lateral recumbency (n = 7), dogs rotated from left to right lateral recumbency (7), and dogs rotated from dorsal to right lateral recumbency (7). Each dog received an epidural injection of 0.05% methylene blue (0.1 mL/kg) at the lumbosacral space. A dorsal laminectomy of the vertebral column was made, and cranial extent of methylene blue in 4 quadrants (right lateral, left lateral, ventral, and dorsal) was determined by examining dura mater staining. RESULTS: No significant difference was found among groups in regard to body weight or body condition score. Epidural cranial migration of methylene blue in the right lateral quadrant was significantly greater in dogs that remained in right lateral recumbency than in dogs that were rotated from left to right lateral recumbency. No significant difference was found within groups for epidural cranial migration of methylene blue between each quadrant. No significant relationship was found between body weight or body condition score and epidural cranial migration of methylene blue. CONCLUSIONS AND CLINICAL RELEVANCE: Body positioning and amount of recumbency time influence cranial migration of epidurally injected methylene blue. If greater cranial migration of an epidurally administered drug is desired, placing the patient in lateral recumbency with the surgical site on the dependent side may precede surgery.     

Radiographic evaluation of positional atelectasis in sedated dogs breathing room air versus 100% oxygen

This study documents the degree of positional atelectasis in sedated dogs receiving 100% oxygen (O₂) versus room air. Initial lateral recumbency was determined by an orthopedic study and initial treatment (O₂ or room air) was randomized. Each dog was maintained in lateral recumbency for 15 min, at which time ventrodorsal (VD) and opposite lateral thoracic radiographs were obtained. Each dog was then maintained in the opposite lateral recumbency and received the other treatment for 15 min, followed by a VD and opposite lateral radiograph. Radiographs were scored for severity of pulmonary pattern and mediastinal shift by 3 radiologists. Dogs breathing O₂ had significantly higher scores than dogs breathing room air. If radiographically detectable dependent atelectasis is present, repeat thoracic images following manual positive ventilation and/or position change to the opposite lateral recumbency should be made to rule out the effect of O₂ positional atelectasis and avoid misdiagnosis.     

Pulmonary thromboembolism associated with Blastomyces dermatitidis in a dog

An 8-year-old, male castrated golden retriever presented for cough and increased respiratory effort. Radiographs revealed an alveolar pattern in the right caudal lung lobe and an opacity at the carina suspected to be enlarged tracheobronchial lymph nodes. The disease progressed to involve the right middle lung lobe. Cytopathology of a fine-needle aspirate and bronchoalveolar lavage fluid were nondiagnostic. Surgical removal of the right caudal lung lobe and biopsy of the perihilar lymph nodes revealed pulmonary thromboembolism and reactive lymph nodes. The dog died several days postoperatively, and necropsy revealed diffuse pulmonary thromboembolism. Additionally, Blastomyces dermatitis organisms were identified in a pyogranulomatous mass surrounding the trachea near the carina. In an extensive literature search, no reports of pulmonary thromboembolism associated with blastomycosis were identified. It is suspected that the inflammation secondary to blastomycosis caused the thromboembolism.     

PRESUMED MINERAL OIL ASPIRATION AND CAVITARY LUNG LESIONS IN A DOG

This report describes an unusual occurrence of cavitary lung lesions which may have been secondary to aspiration of mineral oil and illustrates a possible danger of aspiration pneumonia associated with administration of lipids. Lipid pneumonia should be considered in the differential diagnosis for pulmonary disease with radiographic signs ranging from increased interstitial opacity to nodules or cavitary lung lesions. This report also emphasizes the benefits of serial radiography to detect changing pathology and the occurrence of complications such as pneumothorax.     

Effect of body position on ultrasonographic estimations of bladder volume

A study was undertaken to determine the effect of body position on ultrasonographic bladder measurements and volume estimations. Of the 42 dogs studied, 15 were fresh canine cadavers without urological disease and the remaining 27 were undergoing investigations for disorders of the lower urinary tract. Bladder volume was estimated using a formula described previously. Irrespective of whether all dogs were considered together or only live animals were included, measurements made in dorsal recumbency tended to underestimate bladder volume while those made in right lateral recumbency resulted in overestimation. This was due to significant differences in all linear measurements, apart from width, between body positions. Measurements in right lateral recumbency were higher than those in dorsal recumbency. In all animals and in living dogs alone, bladder measurements in dorsal recumbency appeared to give a more accurate estimation of actual bladder volume.     

Effect of left vs. right recumbency on the vertebral heart score in normal dogs

The effect of right vs. left recumbency on computation of the vertebral heart score (VHS) was assessed in 63 healthy dogs. The VHS was significantly higher in right lateral recumbency (9.8 +/- 0.6 vs. 9.5 +/- 0.8; P < 0.0004). Gender and dog size did not significantly influence VHS values while there was m oredifference between left and right side measurements when considering the type of thorax (P = 0.055).     

Gastro-oesophageal reflux in halothane anaesthetized sheep. The effects of feeding and positioning

The frequency of gastro-oesophageal reflux (GOR) in sheep anaesthetized with halothane was reduced by withholding food and water for 24 hours. The total reflux volume increased. The effect of body position on GOR was studied by inclining the operating table at angles to the horizontal and positioning the head up or down on sand bags. The operative positions investigated were: right and left lateral recumbency with head down, dorsal recumbency with head down and right lateral recumbency with head up. Least GOR occurred when the sheep was in right lateral recumbency with a head up tilt and the body inclined at 20° from the horizontal. A cuffed oesophageal drainage tube increased the incidence of GOR but prevented the chances of the aspiration of rumen material.     

Hypertrophic osteopathy associated with pulmonary Eikenella corrodens infection in a dog

CASE DESCRIPTION: A 4-year-old English Pointer was examined because of chronic, progressive signs of pulmonary disease and failure to respond to medical treatment. CLINICAL FINDINGS: At examination, radiography of the thorax revealed increased pulmonary opacity and air bronchograms in the right caudal lung lobe, and radiography of the forelimbs revealed periosteal bone production typical of hypertrophic osteopathy. Attempts to isolate a causative organism included bacterial culture of bronchoalveolar lavage fluid and a lung tissue specimen obtained via fine-needle aspiration. Despite a cytologic diagnosis of septic suppurative inflammation in the lavage fluid, those specimens did not yield bacterial growth. However, a biopsy specimen obtained during a lung lobectomy procedure yielded growth of Eikenella corrodens. TREATMENT AND OUTCOME: Despite successful surgical removal of the consolidated lung lobe and initiation of antimicrobial treatment, the dog died 6 days after surgery. CLINICAL RELEVANCE: The authors are not aware of reports of pulmonary infection with E. corrodens in animals. Infection with the organism is rare, but it is possible that infections are underreported given that the organism is difficult to culture and biopsy may be necessary to obtain enough tissue to yield a diagnosis.     

Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. VI. Radiological/pathological correlations

This study was initiated to determine if the extent and intensity of lung lesions associated with exercise-induced pulmonary haemorrhage (EIPH) in horses could be predicted from thoracic radiographs. Sets of thoracic radiographs from 24 horses with varied histories of EIPH were subjectively coded for radiographic quality, and perceived extent and intensity of diffuse interstitial opacity by three radiologists who had no knowledge of the corresponding autopsy results. Codes assigned from radiographs for the chosen parameters were compared with coded estimates of lung surface staining assigned at post mortem and volume measurements of haemosiderin deposits and bronchial arterial neovascularisation recorded from lung slices in separate studies. The non-parametric Spearman rank correlation test was used to test for statistical significance. All radiographically coded estimates of lesion severity were positively correlated with post mortem measurements of actual lesion involvement, but only the correlation between coded estimates of lesion opacity versus haemosiderin deposits and bronchial artery neovascularisation were statistically significant (P less than 0.05). Correlations between radiographic codes for lesion extent versus haemosiderin deposits and neovascularisation were just beyond the level of significance (P greater than 0.05 less than 0.1). These findings indicate that there are graded, radiographically discernible increases in interstitial opacity related to actual lesion severity. However, under the conditions of the study, accurate prediction of lung pathology in individual cases based on radiographic criteria was precluded by the wide variance of the coded values. The authors believe that with good radiographic technique and careful criteria selection, satisfactory prediction of lesion severity in EIPH cases could be achieved.     

Cardiovascular and pulmonary effects of recumbency in two conscious ponies

Respiratory dead-space, tidal volume, respiratory rate, blood gases, cardiac output, heart rate and arterial and pulmonary arterial blood pressures were measured in two conscious, trained ponies in the standing position and in left lateral recumbency. The ponies were reluctant to remain lying down for more than about 20 mins but the reason for this did not become apparent. Tidal volume was reduced during recumbency but the respiratory rate increased, tending to maintain the minute volume at about that of the standing animal. Arterial carbon dioxide tension did not change significantly from standing values but the mean arterial oxygen tension values tended to decrease in both ponies during recumbency because of a slight increase in pulmonary venous admixture. Venous admixture in these two laterally recumbent conscious animals was considerably less than previously reported for anaesthetised subjects.     

Radiographic evidence of pulmonary dysfunction in anaesthetised cattle

The effects of fasting, sedation, recumbency and general anaesthesia on the radiographic appearance of the thoracic cavity of adult cattle were investigated. Fasting and sedation had little effect on the visible lung field but recumbency and general anaesthesia were followed by a reduction in lung field area. The reduction in area appeared to be greatest in the more dependent parts of the lung and was associated with the development of a persistent radiographic opacity. The changes were similar to those previously observed in horses.     

ACQUIRED CYSTIC BRONCHIECTASIS IN THE DOG: A CASE HISTORY REPORT

A 9-year-old neutered female mixed breed dog was examined for productive coughing, gagging, increased respiratory effort and restlessness. In survey chest radiographs a soft tissue opacity was present in the right middle lung lobe. In horizontal-beam radiographs, it was apparent that the opacity was a thin-walled cyst containing air and fluid. Peribronchial infiltration and bronchial dilation were present in all lung lobes. At necropsy, a diagnosis of chronic bronchitis and bronchiolitis and cylindrical and cystic bronchiectasis was made. Acquired bronchiectasis may result from any disease process which weakens the bronchial wall or obstructs drainage. Three forms of bronchiectasis have been described in man: cylindrical, saccular and cystic. Cylindrical bronchiectasis is tubular distention of larger, thick-walled bronchi; saccular bronchiectasis is circumscribed outpocketing of intermediate-sized bronchi and cystic bronchiectasis is a more pronounced manifestation of saccular bronchiectasis in terminal bronchi. Cylindrical and saccular bronchiectasis have been described in the dog; cystic bronchiectasis has not been described in the dog. Generalized bronchiectasis is an incurable condition due to the irreversible bronchial pathologic changes. Focal bronchiectasis can be surgically corrected by lobectomy and the prognosis is good. Aggressive antibiotic therapy should be used to treat chronic bronchitis in an effort to prevent bronchial destruction and development of bronchiectasis.     

Radiographic and computed tomographic evaluation of experimentally induced lung aspiration sites in dogs

This study was performed to radiographically examine the prevalence of aspiration sites and to evaluate their atomical correlation with the bronchial pattens. Ten healthy beagle dogs were repeatedly radiographed, at weekly intervals, in the left and right lateral, ventrodorsal (VD) and dorsoventral (DV) positions. Three mililiters of iohexol distilled with same volume of saline was infused into the tracheal inlet. Which lung lobe was aspirated was decided upon by the presence of a significant alveolar pattern due to the contrast medium. Alveolar patterns were identified at the left (100%) and right cranial lung lobes (77%) with the dogs in dependant lateral recumbency, at the right caudal lung lobe (71%) with the dogs in VD recumbency and at the right middle lung lobe (59%) with the dogs in DV recumbency, respectively. The anatomical correlation was evaluated by performing computed tomography. The right principal bronchus (165.8 ± 1.6°) was more straightly bifurcated than was the left principal bronchus (142.7 ± 1.8°, p < 0.01). In VD position, the right side lung had a greater opertunity to become aspirated. The ventrally positioned right middle lobar bronchial origin was more easily to be aspirated the other laterally positioned ones. We think that these anatomical characteristics can be one of the causes for aspiration pneumonia to occur more frequently in the right side lung.     

RADIOGRAPHIC HEART-VOLUME ESTIMATION IN NORMAL CATS

Heart volume mensuration was evaluated on conventional radiographs from eight normal cats in different body positions using computed tomography (CT). Heart volumes were calculated from orthogonal thoracic radiographs in ventral and dorsal recumbency and from radiographs exposed with a vertical X-ray beam in dorsal and lateral recumbency using the formula for an ellipsoid body. Heart volumes were also estimated with CT in ventral, dorsal, right lateral and left lateral recumbency. No differences between heart volumes from CT in ventral recumbency and those from CT in right and left lateral recumbency were seen. In dorsal recumbency, however, significantly lower heart volumes were obtained. Heart volumes from CT in ventral recumbency were similar to those from radiographs in ventral and dorsal recumbency and dorsal/left lateral recumbency. Close correlation was also demonstrated between heart volumes from radiographs in dorsal/ left lateral recumbency and body weights of the eight cats.     

POSITIVE-CONTRAST ARTHROGRAPHY

Normal colony Beagle dogs were used to evaluate the effect of concentration, volume, and limb positioning on positive-contrast arthrography in the humeral joint. An 8.4% w/v (33.3 mg/ml ± volume) concentration of analytic grade metrizamide (33 mg/ml of iodine) was thought to provide arthrograms of the highest diagnostic quality. Optimal volume of contrast medium was 2–4 ml in dogs with weight of 7.0–15.6 kg (mean, 10.3 kg). Radiographs thought to be of greatest diagnostic value were those made with the dog in lateral recumbency and the limb positioned for neutral, traction, flexion, supination, and pronation views, plus a caudocranial radiograph made with the dog in dorsal recumbency and the limb in traction.