Pulmonary embolization of vascular occlusion coils in dogs with patent ductus arteriosus

Transcatheter coil embolization of patent ductus arteriosus (PDA) was performed in 206 dogs between 1994 and 2003 at Texas A&M University, of which 7 (3%) had embolization of coils to the pulmonary vasculature. Thoracic radiographs indicated that coils were located in the right pulmonary artery in 6 of the 7 dogs. Pulmonary perfusion scans were available for review in 5 dogs, and moderate perfusion defects were observed in the right caudal lung lobe in 4 dogs within 24 hours of embolization. Perfusion deficits observed initially in 2 of the dogs resolved on perfusion scans performed at 6 months and 3.1 years. One dog did not have evidence of focal perfusion defects on a perfusion scan performed 4.5 months after embolization. All pulmonary embolizations occurred during the procedure. Attempts at retrieval of coils were unsuccessful in the 2 dogs in which it was attempted. No short- or long-term clinical complications were observed in any of the dogs with pulmonary embolization. We conclude that pulmonary embolization of vascular occlusion coils is an uncommon event and is not typically associated with adverse clinical effects in dogs with PDA.     

Pulmonary embolism associated with canine total hip replacement

OBJECTIVE: To determine by pulmonary perfusion scans and ultrasonography if embolemia occurs during total hip replacement (THR) surgery in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Forty client-owned dogs that had THR surgery. METHODS: Thoracic radiographs were taken immediately after THR and immediately after completion of (99m)Tc-MAA lung scans. Scintigraphy was performed in 28 dogs, 48 hours after THR. Intraoperative ultrasonography (intercostal or transesophageal) was performed in another 12 dogs that had THR. The right atrium and ventricle and pulmonary outflow tract were observed during and for 5 to 8 minutes after femoral component insertion into medullary canals prepared by reaming, and lavage and aspiration of debris before filling with polymethylmethacrylate in dough stage. A modified Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) classification system was used to evaluate lung scans. RESULTS: No pulmonary radiographic abnormalities were identified. Segmental and subsegmental perfusion defects occurred in 23 (82%) dogs and were classified as severe in 9 (32%) dogs, moderate in 11, and mild in 3. There was no particular lobe predilection. Patchy mulberry-appearing defects, indicative of fat embolism, were most common. Embolemia was observed by ultrasound in 10 dogs. Variable-sized particles occurred in 8 dogs, particles and bubbles in 2 dogs, and no emboli were observed in 2 dogs. Embolemia was observed within 10 seconds after femoral stem insertion and lasted < 1 minute. Pneumoemboli remained in the right atrium for > 8 minutes before dislodgement. CONCLUSIONS: Embolemia of either air, particles, or both occurs in most dogs during THR surgery. CLINICAL RELEVANCE: Most dogs seemingly spontaneously recover from pulmonary embolism that occurs during THR. The risk of clinical complications from this pulmonary embolism should be taken seriously, even though the exact morbidity and mortality rates are unknown.     

PULMONARY ANGIOGRAPHY WITH 64‐MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHY IN NORMAL DOGS

Pulmonary angiography using 64‐multidetector‐row computed tomography (MDCT) was used to evaluate pulmonary artery anatomy, and determine the sensitivity of pulmonary artery segment visualization in four Beagle dogs using images reconstructed to 0.625 mm and retro‐reconstructed to 1.25 and 2.5 mm slice thickness. Morphologically, characteristic features included a focal narrowing in the right cranial pulmonary artery in all dogs, which should not be mistaken as stenosis. While the right cranial pulmonary artery divided into two equally sized branches that were tracked into the periphery of the lung lobe in all dogs, only a single left cranial (cranial portion) lobar artery was present. Compared with 1.25 and 2.5 mm retro‐reconstructions, 0.625 mm reconstructions allowed for detection of significantly (P≤0.05) more pulmonary artery segments and sharper depiction of vessel margins. Clinical applications such as prevalence and significance of diameter changes, and detection of pulmonary arterial thrombembolism on lobar and sublobar level, using pulmonary angiography with 64‐MDCT applying 0.625 mm reconstruction slice thickness remain to be established.     

Exercise-induced pulmonary haemorrhage in the horses: results of a detailed clinical, post mortem and imaging study. VII. Ventilation/perfusion scintigraphy in horses with EIPH

Detailed post mortem examination of the lungs of horses with exercise-induced pulmonary haemorrhage (EIPH) has demonstrated significant small airway disease and intense bronchial arterial proliferation in the dorsocaudal lungfields. The purpose of this study was to investigate ventilation and perfusion distribution in the lungs of a similar group of horses to compare changes in the live animal with the previously reported post mortem findings. Thoracic radiography and ventilation/perfusion (V/Q) scintigraphy were performed on five racing Thoroughbreds with recent histories of EIPH. Parametric images of V/Q ratios for left and right lungfields were also generated from the scan images. In all horses, ventilation and perfusion deficits were demonstrated in the dorsocaudal areas of the lung corresponding closely to the observed radiographic lesions. In particular, the perfusion images and V/Q ratio displays indicated that, in affected areas of lung, pulmonary arterial perfusion was the more seriously impaired. This finding appears to confirm the post mortem evidence of reduced pulmonary arterial perfusion and bronchial arterial dominance in these areas. Ventilation deficits in the same areas also confirmed the likelihood of partial airway obstruction consistent with the small airway disease noted in previous post mortem observations. These results suggest that the vascular and airway lesions demonstrated in detailed post mortems of horses with EIPH are also functionally important in affected horses, even at rest. As a consequence of the apparent persistent, insidious and progressive nature of the lesions associated with EIPH there are serious long term implications for management of the condition.     

COMPUTED TOMOGRAPHY BRONCHIAL LUMEN TO PULMONARY ARTERY DIAMETER RATIO IN DOGS WITHOUT CLINICAL PULMONARY DISEASE

Bronchiectasis is diagnosed in humans using multiple computed tomography (CT) criteria, the most important being dilatation of the bronchi. The most widely used criterion for detection of bronchial dilatation is a bronchial lumen to pulmonary artery diameter (bronchoarterial [BA]) ratio >1.0. No studies have been performed to determine the BA ratio in normal dogs. Thoracic CT images of 24 dogs without clinical pulmonary disease were reviewed. The BA ratio of the lobar bronchi of the left cranial (cranial and caudal parts), right cranial, right middle, left caudal, and right caudal lung lobes was measured. The mean of the mean BA ratio for all dogs was 1.45±0.21 (99% confidence interval [CI]=1.34–1.56). The mean of the mean BA ratio as determined by lung lobe was 1.45±0.04 (99% CI=1.41–1.49). The range of individual BA ratios was 0.8–2.0. There was no significant difference in mean BA ratios as a function of lung lobe ( P =0.60). The BA ratio in these clinically normal dogs was consistent and may be a useful tool in evaluating for bronchiectasis on CT images. BA ratios >2.0 were not identified in this population, suggesting a threshold to differentiate normal from abnormal bronchi.     

ACCURACY OF A COMPUTED TOMOGRAPHY BRONCHIAL WALL THICKNESS TO PULMONARY ARTERY DIAMETER RATIO FOR ASSESSING BRONCHIAL WALL THICKENING IN DOGS

Computed tomography is increasingly being used in veterinary medicine to evaluate animals with pulmonary signs such as coughing, tachypnea, and exercise intolerance, however, a quantitative measure of bronchial wall thickening has yet to be validated in veterinary medicine. Canine chronic bronchitis is a disease that is characterized histologically by thickening of the bronchial walls. Thoracic CT images of 16 dogs with chronic bronchitis and 72 dogs presenting for conditions unrelated to cough were evaluated. A ratio comparing the bronchial wall thickness to the adjacent pulmonary artery diameter was obtained in the right and left cranial and caudal lung lobes. There was no significant difference in dogs with chronic bronchitis or unaffected dogs between the left and right hemithorax, patient weight, patient age, image slice thickness, or CT machine used. Dogs with chronic bronchitis were found to have a significantly greater ratio than unaffected dogs (P < 0.001). The ratios in the cranial lung lobes were found to be significantly greater than the caudal lung lobes in both chronic bronchitis and unaffected dogs (P < 0.001). A receiver operating characteristic curve of the ratios in the cranial lung lobes had an area under the curve of 0.912, indicating high accuracy in predicting for bronchial wall thickening. A ratio of ≥0.6 in the cranial lung lobes was found to have a sensitivity of 77% and specificity of 100% in predicting for the presence of chronic bronchitis, and we propose using this cut‐off as supportive of bronchial wall thickening on CT.     

Use of computed tomography and silicon endocasts to identify pulmonary veins with echocardiography

The pulmonary veins were identified from the silicone endocast heart models of 19 dogs. Although variation in the number of the more peripheral veins on each specimen existed, all of the casts had a consistency with regards to the most proximal coalescence of the pulmonary veins as they entered the body of the left atrium. That is, the confluence of the veins formed three ostia at the atrial entry point that consisted of 1) right cranial and right middle pulmonary lobe veins; 2) right caudal, accessory, and left caudal pulmonary lobe veins; and 3) both the left cranial and left caudal pulmonary lobe veins of the left cranial lung lobe. The location of these structures identified by the 3-dimensional endocasts were then used to assist in the identification of the pulmonary veins using computed tomography of 2 dogs. Slices were made that approximated those commonly performed during echocardiographic examination. Understanding which pulmonary veins are seen by echocardiography in the different imaging planes will permit prospective evaluations of pulmonary vein size and abnormal flow patterns.     

THORACIC RADIOGRAPHIC CHARACTERISTICS OF CANINE INFLUENZA VIRUS IN SIX DOGS

Canine influenza virus is an emerging, highly contagious, respiratory pathogen that has not previously been radiographically described. In this retrospective case series study, we describe the thoracic radiographic appearance of confirmed canine influenza virus in six dogs. Radiographic findings varied, but included abnormal unstructured interstitial (one) and unstructured interstitial and alveolar (five) pulmonary patterns, which were distributed cranioventral (four), diffuse (one), and caudodorsal (one). The right middle (five), left cranial (five), and right cranial (four) lung lobes were most commonly affected. Additionally, mild pleural effusion was present in one dog. Intrathoracic lymphadenopathy and cranial mediastinal widening/fluid accumulation were not detected in any dog. Canine influenza virus should be considered as a differential diagnosis for canine patients with respiratory signs and a cranioventral unstructured interstitial to alveolar pulmonary pattern.     

THORACIC RADIOGRAPHIC ABNORMALITIES IN 200 DOGS WITH SPONTANEOUS HEARTWORM INFESTATION

Thoracic radiographs of 200 dogs with spontaneously occurring heartworm disease were reviewed. Radiographs of 28 dogs (14%) were normal. In the remaining 172 dogs various combinations of cardiopulmonary abnormalties were found. The most frequently observed combination, noted in 61 of 200 dogs, was right ventricular, main pulmonary, and right cranial lobar pulmonary artery enlargemetn. Dogs with severe increse of one parameter generally had severe increase of the other two parameters also. One hundred five of the 200 dogs had a right cranial lobar pulmonary artery of normal size. Thus, right cranial lobar pulmonary artery size, when normal, is not a sensitive indicator of the absence of heartworm disease. There was a statistically significant positive relation between the size of the caudal vena cava and that of the right ventricle.     

Dynamic computed tomographic quantitation of hepatic perfusion in dogs with and without portal vascular anomalies

OBJECTIVE: To compare hepatic, pancreatic, and gastric perfusion on dynamic computed tomography (CT) scans of clinically normal dogs with those of dogs with portal vascular anomalies. SAMPLE POPULATION: Dynamic computed tomography (CT) scans of 10 clinically normal dogs and 21 dogs with portal vascular anomalies. PROCEDURES: Retrospective analysis of dynamic CT scans. Hepatic arterial perfusion, hepatic portal perfusion, total hepatic perfusion, hepatic perfusion index, gastric perfusion, and pancreatic perfusion were calculated from time attenuation curves. RESULTS: Mean +/- hepatic arterial perfusion was significantly higher in affected dogs (0.57 +/- 0.27 mL/min x mL(-1)) than in clinically normal dogs (0.23 +/- 0.11 mL/min x mL(-1)), and hepatic portal perfusion was significantly lower in affected dogs (0.52 +/- 0.47 mL/min x mL(-1)) than in clinically normal dogs (1.08 +/- 0.45 mL/min x mL(-1)). This was reflected in the hepatic perfusion index, which was significantly higher in affected dogs (0.59 +/- 0.34), compared with clinically normal dogs (0.19 +/- 0.07). Gastric perfusion was significantly higher in dogs with portal vascular anomalies (0.72 +/- 0.44 mL/min x mL(-1)) than in clinically normal dogs (0.41 +/- 0.21 mL/min x mL(-1)), but total hepatic perfusion and pancreatic perfusion were not significantly different. Among subgroups, dogs with congenital intrahepatic portosystemic shunts and dogs with arterioportal fistulae had higher hepatic arterial perfusion than did clinically normal dogs. Dogs with congenital intrahepatic portosystemic shunts also had an increase in gastric perfusion and hepatic perfusion index. CONCLUSIONS AND CLINICAL RELEVANCE: Hepatic perfusion variables measured on CT scans revealed differences in hemodynamics between clinically normal dogs and those with portal vascular anomalies.     

Frequency of pulmonary mineralization and hypoxemia in 21 dogs with pituitary-dependent hyperadrenocorticism

The purpose of this study was to determine the frequency of hypoxemia and pulmonary mineralization using ^99mTc-methylene diphosphonate (^99mTc-MDP) in dogs with pituitary-dependent hyperadrenocorticism (PDH). Twenty-one dogs with PDH were pro-spectively evaluated using thoracic radiography, arterial blood gas analysis, and bone phase and pulmonary perfusion scintigraphy (using ^99mTc-macro-aggregated albumin [^99mTc-MAA]). The radiographs and bone and perfusion studies were evaluated subjectively. An averaged quantitative count density ratio was calculated between the thorax and cranial thoraco-lumbar vertebrae from lateral thoracic ^99mTc-MDP images. Thoracic: vertebral ratios were calculated using ^99mTc-MDP studies from 21 control dogs. The thoracic: vertebral ratios were compared between the 2 groups (PDH and control). The mean age (±SD) of the 21 PDH dogs was 10.2 (±3) years, whereas the mean age of the control group was 9.8 (±3) years. Seven of the 21 dogs with PDH were hypoxemic (denned as an arterial partial pressure of oxygen [PaO₂] <80 mm Hg) with an average PaO₂ (±SD) of 62 (±15) mm Hg. Of the 7 hypoxemic dogs, 2 were found to have pulmonary mineralization based on bone scintigraphic images. Pulmonary perfusion abnormalities were not identified using ^99mTc-MAA in any of the 21 PDH dogs. Six PDH dogs had an abnormal interstitial pulmonary pattern and 5 of these dogs were hypoxemic. The average quantitative thoracic: vertebral ratio was not significantly different between the PDH and control dogs (0.5 ± 0.4 versus 0.4 ± 0.1, P = .16). Causes of hypoxemia other than pulmonary thromboembolism should be considered in dogs with PDH. Pulmonary mineralization may contribute to hypoxemia in dogs with PDH.     

Study of lobation and vascularization of the lungs of wild boar (Sus scrofa)

The purpose of this study was to describe the anatomy of the lungs of wild boars for comparison with those of domestic swine. It was found that the right lung of the wild boar is divided into four lobes: cranial, median, caudal and accessory, whereas the left lung is divided into two lobes: cranial and caudal. In 93.4% of the cases, right pulmonary artery separates into the ascendant, descendant, median, accessory and caudal branches. In 73.3% of the cases, left pulmonary artery separates most frequently to form three branches to the cranial lobe, whereas the median lobe is generally supplied by only one arterial branch. There is a single pattern of bronchial distribution: in the right lung a tracheal bronchus leads to the cranial lobe, where it separates into the cranial and caudal bronchi and there are also bronchi to the median, caudal and accessory lobes. In the left lung, the large bronchus separates to form two branches, one of which further separates to form two branches to the cranial lobe whereas the other forms a single branch to the caudal lobe.     

Effect of posture and anaesthesia on the distribution of pulmonary perfusion and lung configuration in beagle dogs

To investigate the effect of posture and anaesthesia on the topographical distribution of pulmonary perfusion in canine lungs, the changes in lung shape, configuration and regional perfusion were assessed in healthy beagle dogs, using a repeated 99mTc perfusion scintigraphic procedure. The general shape of the lung images was similar in standing and prone postures, except for a relative increase of the more ventral zone in the prone posture, ascribed to vertical flattening of the lung associated with enlargement of the ventral zones. Configuration changes revealed a shift of the parenchyma towards the more caudal parts in the prone posture, which suggests a parenchymal compression of the paradiaphragmatic lung zones. The prone posture induced a decreased perfusion to the caudal third of the lung. Anaesthesia induced significant changes in lung shape without an obvious direction. The perfusion to the more ventral as well as to the more cranial zones was reduced. Differences in the perfusion distribution are thought to be mainly due to the pressure exerted by the abdominal content through the diaphragm and to the shift of the blood towards better ventilated lung regions.     

PULMONARY MINERALIZATION IN FOUR DOGS WITH CUSHING'S SYNDROME

The clinical and imaging features of four dogs with Cushing's syndrome and pulmonary mineralization are reviewed. Three dogs presented with a primary complaint of respiratory distress/dyspnea. Three dogs had pituitary dependent Cushing's syndrome, while the remaining one dog had iatrogenic Cushing's syndrome. Each dog had clinical features typical for Cushing's syndrome. Two of the dogs were euthanized due to progressive hypoxemia. In each dog, the serum calcium, phosphorous, blood urea nitrogen and creatinine were normal.
A generalized increase in unstructured interstitial pulmonary opacity with diffuse mineralization was noted on thoracic radiographs of all dogs. In one dog, an ill-defined nodular interstitial pattern of mineralization was present. Delayed bone phase scintigraphy using ^99mTechnetium methylene diphosphonate documented generalized pulmonary uptake in two dogs. ^99mTechnetium labeled microaggregated albumin lung perfusion scans were normal in these two dogs. ^99mTc-MDP scintigraphy can provide useful information in diagnosing pulmonary mineralization in Cushingoid dogs.     

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.     

RADIOGRAPHIC EVALUATION OF CANINE HEARTWORM DISEASE COEXISTING WITH RIGHT HEART FAILURE

Thoracic radiographs of 28 dogs with heartworm disease and right heart failure were evaluated subjectively and objectively. Radiographs of all dogs were abnormal. Abnormalities were consistent with those previously reported for heartworm disease but were more severe than those identified in another group of heartworm dogs that did not have right heart failure. The right ventricle and right caudal labor pulmonary artery were enlarged in every dog. The main pulmonary artery, right cranial lobar pulmonary artery, and caudal vena cava were enlarged in 24, 25, and 17 dogs, respectively. Radiographically apparent pathologic pulmonary conditions were present in 25 dogs. Pleural effusion was not identified.     

IMAGING CHARACTERISTICS OF INTRATHORACIC HISTIOCYTIC SARCOMA IN DOGS

In this retrospective study, two observers independently reviewed thoracic imaging studies of 39 dogs with confirmed histiocytic sarcoma. The most common findings were intrathoracic lymphadenopathy, identified by the first and second observers in 82.1% and 87.2% of dogs, respectively, and pulmonary masses (74.4% and 82.1%). Right middle lung lobe masses were significantly more common than masses in any other lung lobe (P<0.0013), with the majority having a ventral distribution. Sternal and tracheobronchial lymphadenopathy were significantly more common than cranial mediastinal lymphadenopathy (P‐values of 0.0002 and 0.012, respectively). Interobserver agreement regarding distribution of lymphadenopathy and pulmonary masses was good (κ=0.64 and 0.75, respectively). Other findings included pulmonary nodules, pleural effusion, and abnormal pulmonary patterns. In patients with CT examinations, the majority of masses were mildly to moderately enhancing and heterogeneous, poorly marginated, and bronchocentric. Lymphadenopathy and pulmonary masses are the most common intrathoracic findings in dogs with histiocytic sarcoma, and the strong predilection for the ventral aspect of the right middle lung lube may help to differentiate it from other types of neoplasia.     

High-resolution computed tomography bronchial lumen to pulmonary artery diameter ratio in anesthetized ventilated cats with normal lungs

High-resolution computed tomography (CT) is the preferred noninvasive tool for diagnosing bronchiectasis in people. A criterion for evaluating dilation of the bronchus is the bronchial lumen to pulmonary artery diameter (bronchoarterial ratio [BA ratio]). A ratio of > 1.0 in humans or > 2.0 in dogs has been suggested as a threshold for identifying bronchiectasis. The purpose of this study was to establish the BA ratio in normal cats. Fourteen specific pathogen-free cats were selected for analysis of thoracic CT images. The BA ratios of the lobar bronchi of the left cranial (cranial and caudal parts), right cranial, right middle, left caudal, and right caudal lung lobes were measured. The mean of the mean BA ratio of all lung lobes was 0.71 +/- 0.05. Individual BA ratios ranged from 0.5 to 1.11. Comparing individual lobes for each cat, there was no significant difference (P = 0.145) in mean BA ratio between lung lobes. A mean BA ratio for these normal cats was 0.71 +/- 0.1, which suggests an upper cut-off normal value > 0.91 (mean +/- 2 standard deviations) between normal and abnormal cats.     

A Retrospective Study of Cavernous Sinus Syndrome in 4 Dogs and 8 Cats

Cavernous sinus syndrome (CSS) is characterized by deficits in more than one of the cranial nerves (CN) that traverse the cavernous sinus at the base of the cranial vault: CN III (oculomotor), IV (trochlear), VI (abducens), and the first two branches of CN V (trigeminal). Records from 4 dogs and 8 cats with CSS diagnosed over a 14-year period were reviewed. The most common clinical signs were ophthalmoparesis or ophthalmoplegia, mydriasis with no direct or consensual pupillary light reflexes, ptosis, decreased corneal sensation, and decreased retractor oculi reflex. All cats had initial signs referable to a left CSS lesion (one had bilateral CSS), whereas in all dogs the lesions were localized to the right cavernous sinus. Median ages at diagnosis were 9 and 10 years of age for dogs and cats, respectively. Cerebel lomedullary cisternae cerebrospinal fluid analysis in 6 animals was useful as a sensitivebut nonspecific diagnostic test of an intracranial inflammatory or neoplastic lesion. Magnetic resonance imaging scans provided a more definitive diagnostic test in all dogs, revealing a contrast-enhancing mass on T1 weighted scans in the region of the cavernous sinus. A definitive pathological diagnosis was obtained in 2 dogs: a primary intracranial neoplasm and a metastatic intracranial neoplasm. A definitive diagnosis was obtained in 6 cats: metastatic neoplasm (n =1), primary intracranial neoplasm (n = I), primary intracranial infectious disease (n = 2). and associated systemic infectious disease (n = 2). The prognosis associated with CSS in dogs and cats was considered guarded to poor. J Vet Intern Med 1996_;10:65–71. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

OSTEOSARCOMA OF THE PATELLA WITH PULMONARY METASTASES IN A DOG

A 6-year-old neutered male Rottweiler was examined for a progressive right pelvic limb lameness. In radiographs of the right stifle, there was an osteolytic lesion with irregular new bone formation along the cranial aspect of the patella consistent with an aggressive bone lesion. In thoracic radiographs, there were multiple soft tissue nodular opacities throughout the lung fields, consistent with pulmonary metastases. Microscopically, fine needle aspirate samples from the right patella contained pleomorphic spindle cells with cytologic features of osteosarcoma. The presence of pulmonary metastases at the time of initial diagnosis in the dog described herein suggests that osteosarcoma of the patella has the potential for similar aggressive biologic behavior as that seen in dogs with appendicular osteosarcoma.