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.     

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.     

RADIOGRAPHIC FINDINGS OF CANINE DYSAUTONOMIA IN TWENTY-FOUR DOGS

Canine dysautonomia is an idiopathic condition resulting in loss of autonomic nervous system function. Recently, the prevalence of dogs diagnosed with dysautonomia in the mid-western United States has increased. In this study the medical records and radiographic findings in 24 dogs with dysautonomia were reviewed. A diagnosis of dysautonomia was made in 17 (71%) of the dogs in this study by postmortem examination, the remaining 7 (29%) dogs were diagnosed pharmacologically. The radiographic findings supportive of dysautonomia include aspiration pneumonia, megaesophagus, or a distended stomach, small bowel, or urinary bladder. In some instances, the disease radiographically mimicked other disorders of the gastrointestinal tract, including mechanical obstruction.     

CARDIAC AND PULMONARY ARTERY MENSURATION IN FELINE HEARTWORM DISEASE

A retrospective study was undertaken to quantify thoracic radiographic changes in cats with heartworm diseases, ( Dirofilaria immitis ). Using a blinded study format, the cardiac silhouette, thoracic cavity and pulmonary arteries were measured from thoracic radiographs of 21 cats with feline heartworm disease and 30 cats without known cardiac or pulmonary vessel pathology. Measured data were normalized to the thoracic cavity or bony structures within the radiographic field of view. The measurements were compared between the two groups of cats using an unpaired, two-tailed Student's t -test, with a p value of < 0.05 being considered significant. Cats with feline heartworm disease had enlargement of the craniocaudal aspect of the cardiac silhouette and normalized cardiac:thoracic ratio (p < 0.05) on the lateral view. Also, there was significant enlargement of the central and peripheral caudal lobar pulmonary arteries and their normalized ratios (p < 0.05) in the heartworm infected cats as visualized on the ventrodorsal projection. Tortuosity of the pulmonary arteries was seen in three of the 21 infected cats. Eleven of the 21 cats with feline heartworm disease had pulmonary parenchymal changes. Based on the present study, central and peripheral pulmonary artery enlargement as viewed on the ventrodorsal radiograph was the single best radiographic indicator of feline heartworm disease.     

RADIOGRAPHIC FEATURES OF PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY IN THE CANINE ELBOW

Primary flexor enthesopathy is a recently recognized elbow disorder and should be considered in the differential diagnosis of elbow lameness. For treatment planning purposes, it is important to make a distinction between primary and concomitant forms of the disease. The purpose of this prospective study was to compare radiographic findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 24), elbow dysplasia (n = 13), and normal dogs (n = 7). All dogs underwent a complete radiographic examination and each radiographic image was evaluated for the presence or absence of following characteristics: irregular medial humeral epicondyle, spur and calcified body. Additionally, the presence or absence of other elbow disorders (medial coronoid process disease, osteochondritis dissecans, ununited anconeal process, incongruity, subtrochlear sclerosis, and osteoarthritis) was recorded. Radiographic characteristics of flexor enthesopathy were found in 86% of painful joints in the primary flexor enthesopathy group and in 100% of painful joints in the concomitant flexor enthesopathy group. Radiographic characteristics of flexor enthesopathy were not found in sound elbow and elbow dysplasia groups. Frequencies and details of individual radiographic characteristics did not differ between primary and concomitant flexor enthesopathy groups. Findings support the use of radiography as a first screening method for detection of flexor enthesopathy, but not as a technique for distinguishing primary vs. concomitant forms.     

SENSITIVITY AND SPECIFICITY OF RADIOGRAPHIC DETECTION OF CANINE ELBOW INCONGRUENCE IN AN IN VITRO MODEL

Canine elbow incongruence is believed to be the consequence of underdevelopment of the radius. The purpose of this study is to determine the sensitivity and specificity of radiography to detect elbow incongruence in an in vitro model and to assess the optimal elbow angle and radiographic beam position. Five normal cadaveric canine left forelimbs were used. A four-pin, type 1 external fixator with a linear motor side bar was fixed to the cranial part of the radius of each limb and a 1 cm segment of bone was removed from the mid-diaphysis to allow radial shortening. Each elbow was subjected to the same protocol. They were radiographed at two different angles (90 degrees and 135 degrees) of flexion, with 10 different radiographic beam positions (centered on the humeral condyle, 3 cm cranial, 3 cm caudal, 3 cm distal, 3 cm proximal, 3 cm cranio-proximal, 3 cm cranio-distal, 3 cm caudo-proximal, 3 cm caudo-distal and on the shoulder joint) and at four different level of radial shortening (0, 1, 2 and 3 mm). In addition, a radiographic view centered on the elbows flexed at 135 degrees was made after simulating weight bearing. The acquired digital images were independently evaluated by three evaluators unaware of the elbows status. The elbows were judged normal, incongruent or borderline based on specific criteria. The sensitivity for detection of elbow incongruence at and beyond 2 mm was excellent at 90 degrees (median = 100% for all views) and good at 135 degrees (median = 80%) of flexion with no difference between examiners. The sensitivity at 1 mm of incongruence was unchanged at 135 degrees but was reduced at 90 degrees of flexion (median = 60%) with a significant difference between the evaluators. The specificity was significantly different between the evaluators and ranged from 70% to 90% at 90 degrees of flexion and from 50% to 80% at 135 degrees. The lowest specificities at 90 degrees were obtained with the proximal displacements of the X-ray beam. Simulating weight bearing significantly decreased the sensitivity at 1 mm (from 80% to 50%) and 3 mm (from 100% to 80%) of incongruence and slightly increased the specificity (from 55% to 65%). Radiography is a sensitive and specific test to detect moderate-to-severe radio-ulnar incongruence (2 mm and over) if the elbow is flexed at a 90 degrees angle regardless of the radiographic beam position. Finally, canine elbow incongruence appeared reduced after an in vitro weight-bearing simulation.     

COMPARISON OF ULTRASONOGRAPHIC AND RADIOGRAPHIC MEASUREMENTS OF CANINE PROSTATE DIMENSIONS

The purposes of this study were to: 1) compare prostatic dimensions measured on radiographic and ultrasonographic images and 2) compare a subjective radiographic assessment of prostate size with a previously-described objective method. Thirty-four male dogs undergoing investigation of prostatic disorders were used. Prostate length and depth were measured from ultrasonographic and radiographic images. A subjective assessment of prostate size ('small', 'normal', or 'enlarged') was made in 29 animals by one of the authors who was unaware of radiographic or ultrasonographic measurements. In addition, the distance from sacral promontory to the pubic brim was also measured. A prostate length or depth of >70% of this distance was defined as 'enlarged' and <70% as 'normal'. After the effects of magnification on radiographic measurements were eliminated, there were no significant differences between prostatic length measured by the two methods. However, a significant difference was obtained between prostatic depth measurements. The subjective assessment agreed with a previously described objective assessment of prostatic size in 21/29 dogs for prostate length but in only 12/29 for depth. Prostatic length varied from 46.6 to 116.4% (mean 75.7%) of the distance from the pubic brim to the sacral promontory. Prostatic depth varied from 33.0% to 94.6% (mean 59.7%) of the same distance. It is recommended that prostate length, rather than depth, be used when evaluating prostate size from lateral abdominal radiographs.     

RADIOGRAPHIC FINDINGS IN CANINE MALIGNANT HISTIOCYTOSIS

Radiographs of 19 dogs diagnosed as having malignant histiocytosis were examined. The most common abnormalities involved the spleen (10), liver (6), lymph nodes (6 thoracic, 4 abdominal), and lungs (6). Other abnormalities involved the spinal column (3), and bones (2). Correlations were made between radiographic appearance and histologic diagnoses. As has been reported, Bernese Mountain Dogs were found to be significantly more often affected than other breeds. Rottweilers and Golden Retrievers were also found to have higher incidence rates. Viewed radiographically, treatment appeared to have little impact on the course of the disease.     

RADIOGRAPHIC APPEARANCE OF EQUINE LUMBOSACRAL AND PELVIC ABNORMALITIES BY LINEAR TOMOGRAPHY

Radiologic findings are described in 20 horses with clinical signs of a caudal lumbar or hindlimb problem; the horses were subjected to linear tomography of the lumbosacral and pelvic regions. The cases could be divided into four groups: sacroiliac arthrosis (6 horses), lumbosacral abnormalities (3 horses), pelvic or lumbar fracture (6 horses), and no radiographic abnormalities (5 horses). Five of the six horses with sacroiliac arthrosis had spur formation, with localized arthrosis at the caudal aspect of the sacral wing and its articulation with the auricular surface of the ilium. In one horse these lesions were confirmed at postmortem examination. The sixth horse, a Standardbred trotter, had more even and widespread arthrosis of the sacroiliac joint. The three lumbosacral abnormalities were present in two horses with fusion of the L₅-L₆ articulation and one horse with a wider than normal sacrolumbar articulation. Linear tomography also proved to be of diagnostic and prognostic value in the evaluation of lumbar and pelvic fractures. Finally, tomography could be used to eliminate the presence of sacroiliac or lumbosacral damage in some horses that presented with clinical signs suggestive of disease of the lumbosacral or sacroiliac region.     

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.     

RETROSPECTIVE ASSESSMENT OF THORACIC RADIOGRAPHIC FINDINGS IN METASTATIC CANINE HEMANGIOSARCOMA

Twenty-one dogs with histopathologically confirmed hemangiosarcoma were evaluated by thoracic radiography for metastatic disease. All dogs had histopathologic examinations of the lungs within two weeks of thoracic radiography. Fourteen dogs had histopathologic evidence of pulmonary hemangiosarcoma; metastatic disease was detected radiographically in eleven of these dogs. The most common radiographic pattern was that of poorly defined small coalescing nodules (8 dogs); other radiographic patterns included well-circumscribed nodules (3 dogs) and alveolar infiltrates secondary to hemorrhage (2 dogs). Differential diagnoses for diffuse, poorly defined, coalescing pulmonary opacities should include hemangiosarcoma in addition to edema, lymphoma, systemic mycoses, fibrosis, allergy, toxicosis, and carcinomas.     

CORRELATION OF RADIOGRAPHIC, ECHOCARDIOGRAPHIC, AND ELECTROCARDIOGRAPHIC SIGNS OF LEFT HEART ENLARGEMENT IN DOGS WITH MITRAL REGURGITATION

Thoracic radiographs of 40 dogs with mitral regurgitation were evaluated for signs of left heart enlargement and classified into three groups based on the degree of left atrial enlargement (mild = group A, moderate = group B, and severe = group C). Echocardiographic enlargement ratios were calculated for the left atrium (LAE_echo), the left ventricle (LVE_echo), and the aorta (AOE_echo) by dividing the measured dimension with the expected dimension normalized for body weight. The incidence of LVH patterns and p-mitrale was recorded on electrocardiograms. With advanced stages of the disease, there was good agreement of the radiographs and echocardiograms with significant differences of the left atrial enlargement ratio between groups. Nine of the 16 dogs from groups A and B, however, had LAE_echo ratios within the normal range. Sixteen dogs with radiographic signs of left ventricular enlargement had normal LVEecho ratios. These disagreements were interpreted as either cardiac enlargement not manifest in the dimensional change measured by the echocardiogram or as overreading of radiographs. The left ventricular wall thickness did not vary significantly between groups. The incidence of p-mitrale was 30%, but this ECG abnormality, when present, reliably identified enlarged left atrial dimensions. Left ventricular hypertrophy patterns of the ECG did not correlate with either the radiographic diagnosis of left ventricular enlargement or the echocardiographic enlargement ratios.     

SCINTIGRAPHIC AND RADIOGRAPHIC APPEARANCE OF THE SACROILIAC REGION IN HORSES WITH GAIT ABNORMALITIES OR POOR PERFORMANCE

Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.     

RADIOGRAPHIC IMAGING OF THE CANINE INTERCONDYLAR FOSSA

The intercondylar fossa is believed to play an important role in the pathology of cranial cruciate ligament rupture and therefore has received considerable attention in the last decade. Accurate radiographic imaging of the intercondylar fossa requires that the central x-ray beam pass through the center of the intercondylar "tunnel". The anatomy of the canine intercondylar fossa is similar to humans, however, the orientations of the intercondylar fossa's differ. Consequently, the positioning techniques described for humans are not appropriate for the dog. To pass through the center of the dog, intercondylar fossa, the central x-ray beam should be 12° (S.D. 1.7°) caudal from the femoral diaphysis in the sagittal plane and obliqued caudolateral to craniomedial 7° (S.D. 0.60°) (caudo78°proximo7° lateralcraniodistomedial oblique). Cross table positioning was used with the hip flexed and the radiograph cassette placed on the cranial surface of the stifle. However, superimposition of the tuber ischii and soft tissues caudal to the femur made 15° to 20° the best angle obtainable. There was not a significant difference (p = 0.17) in the notch width index between a 12° versus 20° angle of the central x-ray beam caudal to the femoral diaphysis, both with 7° of external rotation of the stifle. The notch width index of 0.252 obtained from radiographic measurements was not significantly different from measurements obtained grossly of 0.254 (n = 26; p = 0.69). Failure to oblique the central x-ray beam caused a significant (p = 0.0008) decrease in the apparent fossa width radiographically.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC EVALUATION OF THE CANINE INTERCONDYLAR FOSSA IN NORMAL STIFLES AND AFTER NOTCHPLASTY IN STABLE AND UNSTABLE STIFLES

The role of the intercondylar fossa in cranial cruciate ligament injury has gained notable attention in humans and it's role is now being questioned in animals. Controversy exists regarding the accuracy of radiographs and computed tomography (CT) in evaluating the intercondylar fossa. This study compared radiographic and CT evaluation with gross evaluation of the intercondylar fossa. Six greyhounds were evaluated before notchplasty, immediately after notchplasty and 6 months after notchplasty in stable and unstable stifles. A fossa width index was used for comparison because it negates the effects of patient size and radiographic magnification. The fossa width index is calculated by dividing the width of the intercondylar fossa by the total condylar width.
The fossa width indices of dogs determined from radiographs and CT were not significantly different before notchplasty except for the cranial fossa width indices which were more inconsistent and tended to underestimate the size when compared to gross measurements. At six months, both stable and unstable stifles had refilling of the notchplasty, but the unstable stifles had significantly greater refilling resulting in no significant enlargement in intercondylar fossa size as compared to the prenotchplasty size. Osteophytes that occurred within the intercondylar fossa were less radiopaque and more easily visualized by computed tomography. Computed tomography provided several advantages, including clearer visualization of the intercondylar fossa, avoiding superimposition of the intercondylar fossa by caudal thigh muscles or tuber ischii and the ability to analyze the cranial and caudal components of the intercondylar fossa separately.     

RADIOGRAPHIC ASPECTS OF INFLAMMATORY LUNG DISEASE IN THE HORSE

The radiographic appearances of inflammatory lung disease in the horse are presented under three major morphologic categories: (a) parenchymal diseases, (b) airway diseases, (c) pleural diseases. Under the category of inflammatory parenchymal disorders, pneumonias of bacterial, viral, mycotic, parasitic, and immunologic origins are discussed. Airway disorders described included bronchitis, bronchiolitis, bronchiectasis, and emphysema. Pleural effusion as well as less common manifestations of pleural disease, are also discussed.     

COMPARISON OF RADIOGRAPHIC AND COMPUTED TOMOGRAPHY LYMPHANGIOGRAPHY FOR IDENTIFICATION OF THE CANINE THORACIC DUCT

Standard radiographic lymphangiograms and computed tomography (CT) lymphangiograms were performed on 10 female dogs without intrathoracic disease. Positive contrast lymphagiography was performed by injection into a catheterized mesenteric lymphatic vessel, and lateral thoracic radiographs, ventrodorsal thoracic radiographs, and thoracic CTs were obtained. The number of visible ducts was recorded for each image at the midbody of the ninth thoracic vertebra (T9) through the first lumbar vertebra (L1). Data were combined for all dogs at each data acquisition point. Data were analyzed by comparing data from all three images independently, and then by combining data for the radiographs and comparing the study with the highest number of visible duct branches to the CT. Significant differences in numbers of branches were found at T11 and L1. This study suggests that CT may be able to quantify branches of the thoracic duct more accurately than standard radiographic lymphangiography.