Evidence of Exposure to Spotted Fever Group Rickettsiae among Arizona Dogs Outside a Previously Documented Outbreak Area

Since 2003, two communities in eastern Arizona have experienced a sustained outbreak of Rocky Mountain spotted fever (RMSF), caused by Rickettsia rickettsii, associated with transmission by Rhipicephalus sanguineus, the brown dog tick; 70 human cases, including eight deaths, were reported from these communities during 2003 through 2008. In both of the affected communities, antibodies to spotted fever group rickettsiae (SFGR) were present in dogs before the notice of the first human cases, suggesting that dogs may serve as useful sentinels for human risk of RMSF in this region. During 2005 and 2006, an exploratory serosurvey was conducted among stray and relinquished dogs presenting to animal control facilities in eastern Arizona located outside the area where human cases had been reported. Antibodies to SFGR were detected in 5.7% (14 of 247) dogs assessed outside the RMSF outbreak area. Animal shelters located in counties that either included or shared large borders with the outbreak area were significantly more likely to have seropositive dogs than facilities in more geographically separated counties (P = 0.01). In addition, stray dogs were significantly more likely to be antibody‐positive than relinquished animals (P = 0.01), suggesting that control of stray dog populations should be considered as a means of limiting SFGR transmission in this region. The findings from this study may be extrapolated to suggest that the current risk for human RMSF infection may extend beyond the noted outbreak area. Heightened surveillance for human disease is needed in the region.     

RADIOGRAPHIC FINDINGS IN TEN DOGS WITH THORACIC ACTINOMYCOSIS

The radiographic findings in ten dogs with thoracic actinomycosis are presented. Radiographic findins varied, but pleural effusion, pulmonary infiltrates and mediastinal masses were most commonly found. Rib involvement, commonly accompanying actinomycosis in man, was present in only one dog. The differential diagnosis of actinomycosis includes many disease entities, but based on the radiographic signs it may be possible to narrow down the number of possiblities considerably. A combination of mediastinal or pulmonary masses, pleural effusion and encapsulated fluid is strongly indicative for actinomycosis. For confirmation a bacteriological examination is indicated.     

Tick infestation and spotted-fever group Rickettsia in shelter dogs, California, 2009

In response to an outbreak of Rocky Mountain spotted fever (RMSF) in Baja California in early 2009, dogs at two shelters in neighbouring Imperial County, California, were evaluated for ectoparasites. Brown dog ticks (Rhipicephalus sanguineus), a recognized vector for RMSF, were found on 35 (30%) of 116 dogs but all ticks tested negative for Rickettsia rickettsii by PCR.     

ABDOMINAL ULTRASONOGRAPHIC FINDINGS IN DOGS NATURALLY INFECTED WITH BABESIOSIS

Canine babesiosis is a tick‐borne disease with a worldwide distribution that can involve multiple organs and result in a wide variety of clinical manifestations. Our goal was to describe the sonographic changes occurring in 72 dogs naturally infected with babesiosis. Seven healthy Beagle dogs were used as a control group. The most common finding in all dogs was splenomegaly with a diffuse heterogenic parenchyma and generally reduced echogenicity. Diffuse hypoechoic hepatomegaly and bilaterally increased cortical echogenicity of the renal parenchyma were found more frequently in severe uncomplicated and complicated babesiosis groups. Mean renal resistive index and pulsatility index (PI) values were 0.66/1.35, 0.73/1.91, and 0.71/1.73 for mild uncomplicated, severe uncomplicated, and complicated babesiosis groups, respectively. A markedly increased PI for complicated and severe uncomplicated groups correlated with anemia and severity of renal damage. Ultrasonography can be an adjunct for diagnosis and monitoring canine babesiosis and its systemic complications. The detection of diffuse heterogeneous splenomegaly can support the diagnosis of Babesia infection, because of the high prevalence of this lesion in these patients.     

THORACIC BLASTOMYCOSIS: A REVIEW OF ITS RADIOGRAPHIC MANIFESTATIONS IN 40 DOGS

Thoracic radiographs of 40 dogs with confirmed blastomycosis were reviewed to determine the incidence of the associated radiographic signs. The predominant patterns of disease were determined in each dog and were as follows: nodular interstitial densities, 13 dogs; a mixed lung pattern not localized to any particular part of the lung, ten dogs; a bronchointerstitial pattern, five dogs; a nonspecific hazy interstitial pattern, four dogs; a mixed alveolar and interstitial density, two dogs; a cavitary lesion, one dog. The lungs appeared normal in four dogs. Concurrent findings included eight dogs with thoracic lymphadenopathy, two dogs with pneumomediastinum, and one dog with pleural effusion. None of the lesions appeared mineralized.     

THORACIC COMPUTED TOMOGRAPHY FINDINGS IN DOGS EXPERIMENTALLY INFECTED WITH ANGIOSTRONGYLUS VASORUM

To characterize the computed tomography (CT) features of thoracic lesions caused by infection with Angiostrongylus vasorum, pre‐ and postcontrast CT was performed in six experimentally infected Beagles 13 weeks postinoculation and in four of these 9 weeks postchemotherapy. Findings were compared with survey radiographs and necropsy findings. A multicentric bronchoalveolar pattern more pronounced at the lung periphery was present radiographically. On CT, the predominant abnormality underlying this alveolar pattern was multiple large nodules merging to areas of consolidation, and containing air bronchograms of varying extent. These nodular changes corresponded to histopathologic granulomata, consisting mainly of macrophages, multinucleated giant cells, and lymphocytes that had accumulated around larvae and eggs. Morphologically, no bronchial changes were observed on CT or histologically. Quantitatively, however, on CT there was evidence of bronchial thickening at 13 weeks postinoculation and mild very peripheral bronchiectasia 9 weeks postchemotherapy. Regional lymph nodes were enlarged after infection, and smaller after treatment. On postcontrast CT, several suspicious intraluminal filling defects suggestive of thrombosis were found; however, the tortuosity of some pulmonary arteries seen radiographically was not present in CT images. After treatment, the consolidations and large nodules had almost completely disappeared. A remaining radiographic interstitial pattern was characterized on CT as ground‐glass opacifications, subpleural interstitial thickening, subpleural lines, and interface signs. These interstitial changes reflected fibrosis as documented histopathologically. CT allowed very detailed and accurate characterization of pulmonary parenchymal lesions, bronchi, and lymphnodes and closely reflected histopathological changes.     

CORRELATION BETWEEN THORACIC RADIOGRAPHIC CHANGES AND REMISSION/SURVIVAL DURATION IN 270 DOGS WITH LYMPHOSARCOMA

A retrospective study was undertaken wherein the medical records and thoracic radiographs of 270 dogs with lymphosarcoma were reviewed to determine the type and frequency of thoracic radiographic changes. Statistical evaluation of the relationship between radiographic, clinical and immunologic factors and the primary remission duration and survival times was performed using univariate and multivariate analysis. One hundred ninety-two dogs (71 %) had some type of thoracic radiographicabnormality, including 80 dogs (29.6%) with pulmonary infiltrates and 164 dogs (64.4%) with thoracic lymphadenomegaly. Only T-cell phenotype (p = 0.0056 for survival, p = 0.0045 for remission) and the presence of cranial mediastinal lymphadenomegaly (p = 0.0005 for survival, p = 0.0129 for remission) were identified as having a significant negative correlation to both primary remission and survival duration by multivariate analysis.     

RADIOGRAPHIC FINDINGS IN DOGS WITH SPONTANEOUS PULMONARY THROMBOSIS OR EMBOLISM

Thoracic radiographs of 21 dogs with necropsy-confirmed pulmonary thrombosis or embolism (PTE) were reviewed. Two major lung patterns were seen: (1) regional oligemia, giving the impression of a hyperlucent zone; (2) alveolar pulmonary infiltrate, indicating hemorrhage or infarction. Hemorrhage and infarction could not be differentiated radiographically. Other common findings were attenuation or loss of visualization of a lobar artery or lobar vein and pleural effusion, particularly with infarction and cardiac disease. PTE was often associated with renal disease (glomerulonephritis, amyloidosis), septic processes, pancreatitis, systemic venous or right heart thrombosis, cardiac insufficiency, and hypercorticism.     

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.     

THORACIC RADIOGRAPHIC FEATURES OF ANTICOAGULANT RODENTICIDE TOXICITY IN FOURTEEN DOGS

Thoracic radiographs and clinical records from 14 dogs with confirmed anticoagulant rodenticide toxicity were reviewed. Twelve of the 14 dogs were presented with a chief complaint of respiratory distress, and 12 had elevated prothrombin and activated partial thromboplastin times consistent with a coagulopathy secondary to a clotting factor deficiency. Thoracic radiographs of the 14 dogs were reviewed and abnomalities included increased mediastinal soft tissue opacity with extra and intrathoracic tracheal narrowing (4/14), increased mediastinal soft tissue opacity without tracheal narrowing (8/14), variable degrees of pleural effusion (13/14) and generalized, patchy interstitial/alveolar pulmonary infiltrates (8/14). Radiographic evidence of cardiomegaly and pulmonary artery abnormalities consistent with concurrent heartworm infestation were detected in one dog. In four dogs, dramatic tracheal narrowing was identified on the lateral thoracic radiograph caused by either mediastinal hemorrhage compressing the trachea or submucosal hemorrhage within the tracheal lumen. The trachea was displaced in a ventral direction in two dogs, and extra and intrathoracic luminal diameter narrowing was evident cranially in all four dogs. Two of these four dogs had soft tissue opacity within the dorsal trachea that extended from the larynx to the intrathoracic trachea. Twelve of the 14 dogs survived with standard treatment protocols utilizing injectable and oral vitamin K₁. One dog died from pancreatitis and disseminated intravascular coagulopathy. The other dog died soon after presentation due to severe, disseminated hemorrhage. Follow-up thoracic radiographs were made in four dogs that survived and showed resolution of the mediastinal, pleural and pulmonary changes within one to five days after the initiation of vitamin K₁ therapy.     

A COMPARISON OF RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC FINDINGS IN 31 DOGS WITH MALIGNANT NASAL CAVITY TUMORS

Nasal cavity radiographs and CT images from 31 dogs with nasal cavity cancer were compared. All dogs had abnormal clinical signs relating to -nasal cancer and histologic confirmation of malignant nasal cavity neoplasia. No dog had cyto reductive surgery prior to imaging. All radiographic and CT examinations were abnormal. CT was more accurate than radiographs in identifying unilateral versus bilateral nasal cavity disease and tumor extension into adjacent structures such as the cranial cavity, hard palate, and pterygopala-tine fossa. The improved accuracy of CT in these respects was not of benefit in the confirmation of nasal cavity disease because radiographs were abnormal in every instance. However, CT may be useful for more accurate tumor staging, predicting possible treatment-related complications, and planning of surgery and radiation therapy. It was also determined that one dorsally located radiation therapy portal bounded laterally by the medial ocular canthi, as described in previous reports, would not have been adequate for encompassing all abnormal tissue in 28 of the 31 dogs evaluated.     

COMPARISON BETWEEN THORACIC RADIOGRAPHIC FINDINGS AND POSTMORTEM DIAGNOSIS OF THORACIC DISEASES IN DYSPNEIC COMPANION RATS (RATTUS NORVEGICUS)

Companion rats are often presented to veterinarians for respiratory difficulties. Dyspnea in rats is most commonly due to infectious pneumonia, and thoracic neoplasia can go undiagnosed ante mortem due to a mistaken interpretation of pneumonia. In domestic carnivores, pulmonary nodular patterns have been shown to correlate with lung neoplastic diseases and infectious diseases. The main objective of this retrospective case series study was to determine whether certain radiographic criteria could be correlated with the presence of thoracic infectious disease and neoplastic disease in companion rats. A secondary objective was to determine whether the patient's sex and age were different between rats diagnosed with infectious versus neoplastic disease. Medical records and thoracic radiographs of dyspneic companion rats presented to the University of California at Davis, William R. Pritchard Veterinary Medical Teaching Hospital during the time period from January 2000 to December 2014 were reviewed. Rats with postmortem confirmation of thoracic lesions were included in the study. Thoracic radiographs were evaluated for positioning, lesion distribution, lung lobe involved, pulmonary pattern, mediastinal and pleural lesions by three observers blinded to diagnosis. Thirty rats were included in the study, including 23 rats with an infectious disease and seven with neoplasia. Mediastinal lesions were significantly more prevalent in the group diagnosed with thoracic neoplasia (P = 0.031), in particular cranially (P = 0.048). Although there was an overlap between the two groups, findings indicated that the presence of cranial mediastinal lesions may be helpful for differentiating neoplastic from infectious disease in rats.     

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.     

ULTRASONOGRAPHIC FINDINGS IN 14 DOGS WITH ECTOPIC URETER

To evaluate ultrasonography as an alternative to contrast radiography for diagnosis of ectopic ureter in dogs, ultrasonography of the urinary tract was performed prospectively in a series of urinary incontinent dogs anesthetized for contrast radiography. Fourteen dogs had ectopic ureter based on surgical, necropsy or unequivocal contrast radiographic findings. There were eight females and six males of a variety of breeds; five were Labrador retrievers. Mean (range) age at the time of diagnosis was 1.2 (0.2–4) years for females and 3.5 (0.3–5) for males (p < 0.05). Ectopic ureters were unilateral in five dogs (2 left; 3 right) and bilateral in nine dogs. Both ultrasound images and contrast radiographs were positive for 21 (91%) ectopic ureters; the same two ectopic ureters were not detected using either modality. The termination of each of the five normal ureters was visible on ultrasound images; two (40%) were visible on radiographs. Other ultrasonographic findings included dilatation of the ectopic ureter and/or ipsilateral renal pelvis in ten (43%) instances, evidence of pyelonephritis in two dogs (with enlargement of the contralateral kidney in one dog), and urethral diverticuli in one dog. Ultrasonography is a practical diagnostic test for ectopic ureter in dogs. In this series there was close correlation between the ultrasonographic and contrast radiographic findings for each ectopic ureter, but ultrasonography enabled more accurate determination of normal ureteral anatomy.     

RADIOGRAPHIC FINDINGS IN THE THORAX OF DOGS WITH LEPTOSPIRAL INFECTION

Thoracic radiographs of 4 dogs with confirmed and 1 dog with suspected leptospirosis were reviewed. In all dogs a reticulonodular pulmonary opacity was noted, affecting the entire lung in 3 and predominantly the caudodorsal lung field in 2 dogs. The radiographic lung pattern described is associated with pulmonary hemorrhage probably due to endothelial damage and vasculitis. Pulmonary manifestations in dogs with leptospirosis may be misinterpreted and attributed to neoplasia, pneumonia, edema, hemorrhage due to disseminated intravascular coagulopathy, adult respiratory distress syndrome and pulmonary thromboembolism.     

COMPUTED TOMOGRAPHIC FINDINGS IN 15 DOGS WITH EOSINOPHILIC BRONCHOPNEUMOPATHY

Eosinophilic bronchopneumopathy is a disease characterized by the infiltration of the lung and bronchial mucosa by eosinophils. The aim of the present study was to describe the CT findings in a large series of dogs with confirmed diagnosis of eosinophilic bronchopneumopathy. Computed tomographic scans of 15 dogs with confirmed diagnosis of eosinophilic bronchopneumopathy were evaluated retrospectively by two boarded radiologists who reached a consensus. Abnormalities were identified in 14/15 (93%) dogs, including pulmonary parenchymal abnormalities in 14/15 (93%) dogs, bronchial wall thickening in 13 (87%) dogs, which was considered marked in eight (53%), plugging of the bronchial lumen by mucus/debris in 11 (73%) dogs, and bronchiectasis in nine (60%) dogs. Pulmonary nodules were identified in 5/15 (33%) dogs including one dog with a mass. All dogs with a nodular lung pattern had additional abnormalities. Lymphadenopathy was present in 10 dogs (67%). Lesions associated with eosinophilic bronchopneumopathy are variable and heterogeneous and encompass a wider variety of computed tomographic features than reported previously. Computed tomographic images were abnormal in the majority of affected dogs, hence CT is a useful modality to characterize the nature and distribution of thoracic lesions in dogs with eosinophilic bronchopneumopathy.     

USE OF RADIOGRAPHY IN COMBINATION WITH COMPUTED TOMOGRAPHY FOR THE ASSESSMENT OF NONCARDIAC THORACIC DISEASE IN THE DOG AND CAT

Computed tomography (CT) of the thorax was performed in 28 dogs and five cats and findings were compared with previous thoracic radiographs. The sample population included all animals that had thoracic radiographs and a CT study within 5 days of each other, where the complete imaging studies were available for review. Thoracic radiographs were considered indeterminate in 31 patients and CT examinations were done to acquire additional information. The presence of additional information from CT relating to presence of pathology, location of pathology, extent of pathology, and involvement of mediastinal structures was recorded. Whether there was a change in diagnosis based on the CT findings was also recorded. In only 4/33 animals (all dogs) did CT fail to provide any new information for the parameters evaluated when compared with survey thoracic radiographs. Additional information about the pathology that was present was gained by CT in 5/5 cats and 21/ 28 dogs. New information on compartmental location of pathology was seen in 4/5 cats and 19/28 dogs. New information on pathology extent was noted in 5/5 cats and 20/28 dogs. Additional information regarding involvement of mediastinal structures was obtained in 2/5 cats and 10/28 dogs. A change in diagnosis was made in 3/5 cats and 13/28 dogs. In conclusion, CT is a valuable tool for evaluating intrathoracic disease. CT provides additional cross-sectional anatomic information that can aid in anatomic localization and evaluation of the extent of the pathology in question.     

COMPARISON BETWEEN CRANIAL THORACIC INTERVERTEBRAL DISC HERNIATIONS IN GERMAN SHEPHERD DOGS AND OTHER LARGE BREED DOGS

Cranial thoracic intervertebral disc herniations have been reported to be rare in dogs due to the presence of the intercapital ligament, however some studies have proposed they may not be uncommon in German Shepherd dogs. The purpose of this retrospective study was to compare cranial thoracic intervertebral disc herniations in German Shepherd dogs and other large breed dogs (control group). Medical records at the Ontario Veterinary College were searched for German Shepherd dogs and other large breed dogs that had magnetic resonance imaging studies including the T1‐T9 region. For each dog and each disc space from T1‐T9, three variables (compression, disc degeneration, and herniation) were recorded and graded based on review of sagittal T2‐weighted images. Twenty‐three German Shepherd dogs and 47 other large breed dogs met inclusion criteria. The German Shepherd dog group had higher scores than the control group for compression (P = 0.0099) and herniation (P < 0.001), but not disc degeneration (P = 0.97). In the German Shepherd dog group, intervertebral discs T2‐T3 and T4‐T5 had an increased risk for compression and T3‐T4 had an increased risk for compression and herniation. Findings from this study indicated that German Shepherd dogs may be more likely than other large breed dogs to have spinal cord compression due to cranial thoracic disc herniations. Imaging of the cranial thoracic spine, including T2‐T3, is recommended for German Shepherd dogs with T3‐L3 neurological signs.     

ULTRASONOGRAPHIC FINDINGS IN DOGS AND CATS WITH GASTROINTESTINAL PERFORATION

A retrospective study was performed to evaluate the sonographic features of gastrointestinal (GI) perforation in dogs and cats. Sonographic findings in 19 animals (14 dogs and 5 cats) included regional bright mesenteric fat (19), peritoneal effusion (16), fluid-filled stomach or intestines (12), GI wall thickening (11), presence of free air (9), loss of GI wall layering (9), regional lymphadenopathy (8), reduced GI motility (7), pancreatic changes (4), corrugated intestines (4), presence of a mass (3), presence of a foreign body (3), and mineralization of the gastric wall (1). In 14 patients, "perforation" was listed as a differential diagnosis by the sonographer. Abdominal radiographs and radiographic reports were available for 14 patients. Radiographic findings were decreased serosal detail (12), free air (8), peritoneal contrast medium (1), and suspected foreign body (1). GI perforation was listed as radiographic diagnosis in eight patients, seven of which had evidence of pneumoperitoneum, and one had leakage of contrast material on an upper GI study. In 9/14 patients with radiography, "GI perforation" was listed as a sonographic diagnosis. In three patients in which free air was diagnosed sonographically, radiographs were either not available (2) or the presence of free air was not detected at presentation (1). Peritoneal fluid analysis was performed in nine patients, five of which were identified as septic inflammation, and the remaining four were classified as neutrophilic inflammation with no etiologic agent identified. The histologic or surgical diagnoses were as follows: three intestinal surgical dehiscence; one percutaneous endoscopic gastrostomy tube site leakage; one duodenal adenocarcinoma; one ileocolic lymphoma; one trichobezoar; one ascarid impaction; and one bobby pin foreign body. In the remaining 10 patients, a focal area of gastric/intestinal ulceration or transmural necrosis with perforation was identified without evidence of an underlying cause.