Successful percutaneous drainage of a refractory caudal mediastinal paraesophageal abscess in a dog.

OBJECTIVE: To describe a novel technique for paraesophageal abscess drainage in a dog. CASE SUMMARY: A 6-year-old dog presented for pyrexia of unknown origin, subsequently confirmed to be due to a paraesophageal abscess. This was managed by the ultrasound-guided placement of a thoracostomy tube into the abscess, allowing drainage to be performed. This led to clinical resolution and, at an 8-month follow-up, the dog continued to do well. NEW OR UNIQUE INFORMATION PROVIDED: Paraesophageal abscessation is typically managed with surgical intervention, which carries inherent risks and complications. This report describes a novel technique that did not require general anesthesia or invasive surgical intervention, achieving clinical remission without any adverse effects. It also summarizes the current literature available on this condition.

Radiographic differentiation of mediastinal versus pulmonary masses in dogs and cats can be challenging.

The ability to differentiate thoracic masses of mediastinal and pulmonary origins is often confounded by their complex spatial relationship. The objectives of this retrospective, observational cross-sectional study were to assess radiographic differentiation of mediastinal versus pulmonary masses, and to determine if there are any correlations with specific radiographic findings. Thoracic radiographs of 75 dogs and cats with mediastinal and/or pulmonary masses identified on CT were reviewed. Radiographic studies were anonymized, randomized, and reviewed twice by three reviewers. Reviewers categorized the origin of each mass(es) as mediastinal, pulmonary, or both. On the second review, the presence or absence of 21 different radiographic findings was recorded for each mass. Agreement between the radiographic and CT categorization of mass origin, as well as inter- and intraobserver agreement, was calculated. Overall agreement between radiographs and CT was moderate for both mediastinal (68.6%) and pulmonary masses (63%). Overall, interobserver agreement was moderate (κ = 0.50-0.74), with moderate to strong intraobserver agreement (κ = 0.58-0.93). Masses within the mediastinum were significantly more likely to displace other mediastinal structures. Alternatively, masses lateral to midline and in the caudal thorax were found to be significantly positively correlated with a pulmonary origin. The results of this study highlight the limitations of radiography for differentiation of mediastinal and pulmonary masses, with mass location and displacement of other mediastinal structures potentially useful for radiographic findings that may help improve accuracy.

Contrast-enhanced ultrasonography characteristics of intrathoracic mass lesions in 36 dogs and 24 cats.

Contrast-enhanced ultrasonography (CEUS) is increasingly available for veterinary patients, however limited studies describe the use of this method for characterizing intrathoracic mass lesions. The aim of this prospective, observational study was to describe CEUS enhancement patterns for intrathoracic mass lesions in a sample of cats and dogs. Sixty patients (36 dogs, 24 cats) were included. Standardized CEUS examinations were performed for 41 pulmonary masses (68%) and 19 mediastinal masses (32%). Final diagnosis was based on cytology and/or histopathology. Absolute time to enhancement (TTE) values were recorded for the intrathoracic mass lesions and spleen. The spleen was used as a reference parenchymal organ to calculate relative TTE (rTTE) values. Absolute TTE of the spleen and intrathoracic mass lesions differed for dogs and cats (P = 0.001). The rTTE values significantly differed between lesions of neoplastic versus non-neoplastic origin (P = 0.004). The majority of neoplastic pulmonary masses were supplied by bronchial arteries (63%), while most nonneoplastic pulmonary masses were supplied by pulmonary arteries (78%). The sensitivity and specificity for detecting pulmonary neoplastic masses with rTTE were 63% and 78%, respectively. Enhancement patterns for mediastinal thymomas and lymphomas significantly differed (P = 0.002). Thymomas enhanced heterogeneously in a centripetal pattern (86%), whereas lymphomas typically enhanced uniformly in a centrifugal pattern (75%). Findings indicated that CEUS is a feasible method for characterizing intrathoracic mass lesions in dogs and cats, however, the diagnostic sensitivity for detecting neoplastic pulmonary masses was low.

The feasibility of contrast enhanced ultrasonography (CEUS) in the diagnosis of non-cardiac thoracic disorders of dogs and cats.

BACKGROUND: This study describes the feasibility of Contrast Enhanced Ultrasonography (CEUS) in the diagnostic work-up of non-cardiac thoracic disorders of small animals. The second aim is to assess the usefulness of CEUS as a direct guide for sample procedures. RESULTS: Forty animals, 28 dogs and 12 cats, were included in the study. Thoracic disorders included 23 pulmonary lesions [primary carcinoma (14), lymphoma (1), sarcoma (1), histiocytic sarcoma (1), abscess (1) and pneumonia (5)] and 17 mediastinal lesions [lymphoma (8), thymoma (3), mesothelioma (1), melanoma (1), carcinomatous lymphadenopathy (1), mixsosarcoma (1), lipoma (1), and abscess (1)]. The majority of neoplastic pulmonary lesions showed an inhomogeneous distribution of contrast medium, whereas inflammatory lesions had a homogenous distribution with typical pulmonary vessels ramification. The majority of mediastinal malignant lesions showed an inhomogeneous distribution pattern. The lung and mediastinal abscesses had peripheral enhancement of the wall with an avascular center. All cytological and biopsy samples obtained after CEUS were diagnostic. Quantitative analysis, performed in 19/23 pulmonary lesions, showed a statistically significant difference (P < 0.0001) between the arrival time of the malignant (7.27 s - range 4.46-13.52 s) and benign (4.52 s - range 2.87-6.06 s) pulmonary lesions. CONCLUSIONS: CEUS may be a useful tool for the evaluation of non-cardiac thoracic lesions. The contrast medium allows for the precise definition of lesion edges, the presence of necrotic areas, and the distribution of pulmonary vessels. Based on our preliminary results, the use of ultrasonographic contrast medium can be recommended for improving the diagnostic usefulness of cytology and biopsy sampling, because CEUS may help to define necrotic areas from viable tissue.

Thyroid scintigraphy findings in 2096 cats with hyperthyroidism.

Thyroid scintigraphy is currently the reference standard for diagnosing and staging cats with hyperthyroidism, but few studies describing the scintigraphic characteristics in a large number of cats have been reported. The objective of this study was to better characterize thyroid scintigraphy findings by evaluating 2096 consecutive cats with hyperthyroidism that were referred over a 3.5-year period. Of these cats, 2068 (98.7%) had a high thyroid-to-salivary ratio (>1.5), whereas 2014 (96.1%) were found to have a high thyroid-to-background ratio (>6.1). When the patterns of the cats' thyroid disease were recorded, 665 (31.7%) had unilateral disease, 1060 (50.6%) had bilateral-asymmetric disease (two thyroid lobes unequal in size), 257 (12.3%) had bilateral-symmetric disease (both lobes similar in size), and 81 (3.9%) had multifocal disease (≥3 areas of increased radionuclide uptake). The number of areas of (99m) TcO(-) 4 uptake in the 2096 cats ranged from 1 to 6 (median, 2), located in the cervical area in 2057 (98.1%), thoracic inlet in 282 (13.5%), and in the thoracic cavity in 115 (5.5%). Ectopic thyroid tissue (e.g. lingual or mediastinal) was diagnosed in 81 (3.9%) cats, whereas thyroid carcinoma was suspected in 35 (1.7%) of the cats. The results of this study support conclusions that most hyperthyroid cats have unilateral or bilateral thyroid nodules, but that multifocal disease will develop in a few cats that have ectopic thyroid disease or thyroid carcinoma. Both ectopic thyroid disease and thyroid carcinoma are relatively uncommon in hyperthyroid cats, with a respective prevalence of ∼4% and ∼2% in this study.

Caudal mediastinal paraesophageal abscesses in 7 dogs.

OBJECTIVE: To report clinical, imaging, and surgical findings associated with caudal mediastinal paraesophageal abscesses (CMPA) in dogs and outcome after surgical treatment. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 7) with CMPA. METHODS: Medical records (April 2005-January 2010) were reviewed for dogs with CMPA treated surgically. Retrieved data were signalment, history, clinical findings, diagnostic investigations, surgical findings, surgical procedures performed, and postoperative recovery. Long-term follow-up information was obtained by telephone questionnaire of owners and referring veterinarians. RESULTS: Median sternotomy (5 dogs) or lateral thoracotomy (2 dogs) was used for access to CMPA, which were drained and partially debrided surgically. In 5 dogs, omentalization of the abscess cavity was performed through a diaphragmatic incision. Foreign material was not identified within any abscess. All dogs were discharged from the hospital and had full recovery. CONCLUSIONS: CMPA should be suspected when there is regurgitation and pyrexia associated with a mass or enlargement in the caudal mediastinum. CMPA appears to have a good prognosis after aggressive surgical therapy.

Omentalisation of a caudal mediastinal abscess in a dog.

A caudal mediastinal abscess was diagnosed in a 2-year-old German Short-haired Pointer with acute onset of lethargy, pyrexia and tachypnoea. The abscess was managed surgically by median sternotomy, abscess content evacuation and omentalisation of the abscess cavity via the diaphragm. Although surgical management of mediastinal abscesses has been reported previously, this is the first report to describe successful management of the condition in a dog by omentalisation.

Endoscopic ultrasonography for the diagnosis of intrathoracic lesions in two dogs.

Endoscopic ultrasound was developed initially in humans to overcome limitations of conventional ultrasound in examining certain internal organs due to intervening bone or air-filled structures. Endoscopic ultrasound has been used most widely in investigation of the gastrointestinal tract in humans, but many intrathoracic applications as well as endoscopic ultrasound-guided techniques have recently been described. Mediastinal and pulmonary structures can be examined with endoscopic ultrasound since a high frequency ultrasound probe can be brought into close contact with the areas of interest via a transesophageal approach. The purpose of this report is to describe the application of endoscopic ultrasound as an aid in the diagnosis of intrathoracic disease in the dog. Two dogs, one with a history of prior esophageal foreign body extraction, the other with apathy, weakness and dyspnea were referred for further investigation. Both dogs had caudal intrathoracic soft tissue opacities diagnosed radiographically, but their origin and nature were difficult to determine. Conventional ultrasound was limiting in both dogs due to their location and superimposition of gas-filled structures. With endosonography lesions were characterized more completely. We have found endoscopic ultrasound to be an elegant diagnostic tool for the investigation of radiographically detected intrathoracic lesions in the dog whose origins are difficult to determine or do not lend themselves to investigation by conventional ultrasound. Endoscopic ultrasound provides valuable diagnostic information complementary to that provided radiographically which aids in therapeutic planning. Endoscopic ultrasound was also more sensitive for detecting mediastinal lymphadenomegaly than radiography in one of the dogs. An additional advantage of endoscopic ultrasound is the fact that US-guided tissue sampling can be performed during the examination.

Caudal mediastinal abscess due to a grass awn (Hordeum spp) in a cat.

A two-and-a-half year-old male, domestic shorthaired cat was presented with a history of chronic expiratory dyspnoea, dysphagia and progressive weight loss. Thoracic radiography revealed a caudal mediastinal mass. Surgical exploration confirmed the presence of an abscess in the caudal mediastinum. Despite the good prognosis, euthanasia was performed at the owner's request and post-mortem examination revealed an abscess that had been caused by a grass awn located within.

Canine pleural and mediastinal effusions: a retrospective study of 81 cases.

Eighty-one cases of canine pleural and/or mediastinal effusions were identified from radiography and ultrasonography records reviewed between 1992 and 2000 at the Queen's Veterinary School Hospital, University of Cambridge. All cases had a follow-up period of at least 12 months. Twenty-eight underlying disease processes were associated with pleural and/or mediastinal effusions. The most common disease was pyothorax (13 cases). Other common diseases identified were idiopathic pericardial effusion, cranial mediastinal mass, idiopathic chylothorax, secondary lung metastases and dilated cardiomyopathy. Approximately one-quarter of all cases recovered completely after initial treatment and one-third of all cases either died during, or were euthanased immediately after, completion of the initial investigations.

Thoracic actinomycosis (arcanobacteriosis) or nocardiosis causing thoracic pyogranuloma formation in three dogs.

OBJECTIVE: To describe three cases of canine thoracic actinomycosis (arcanobacteriosis) or nocardiosis in which the primary pathological lesion was a pyogranulomatous abscess in the mediastinum. Clinical signs, difficulties in diagnosis, treatment and prognosis are examined. Comparisons are made between human and veterinary literature to assist in formulating a rational treatment plan. DESIGN: Retrospective clinical study. PROCEDURE: Review of case records from 1984 to 1998. RESULTS: Three dogs presented with large intrathoracic pyogranulomas producing variable clinical signs, not necessarily associated with the respiratory tract. Ages ranged from 2 to 5 years old. Two dogs responded to surgical opening and passive drainage of the abscess, or surgical excision of the granuloma with associated structures, and medical therapy. One dog died intra-operatively. CONCLUSION: A combination of surgical and antimicrobial therapy may carry a fair-to-good prognosis for thoracic granuloma caused by actinomycosis (arcanobacteriosis) or nocardiosis. The extent of surgery should be based on assessment of individual cases and must include surgical biopsy for histology and culture to enable a specific diagnosis to be made. Complete surgical excision is not necessarily required. Prolonged antimicrobial therapy is indicated.

Ultrasonography of the thorax (excluding the heart).

Until recently, ultrasonography has had a subordinate role in the evaluation of the thorax in both small animals and humans, most likely due to the inability of sound to penetrate air-filled lung. When pathologic processes such as pleural effusion and lung consolidation provide an acoustic window to the thorax, however, thoracic ultrasonography becomes feasible. As this article illustrates, ultrasonography may be effectively employed in the diagnosis and management of various thoracic wall, pleural, mediastinal, pulmonary, and diaphragmatic diseases by providing valuable information not obtainable with routine radiography and enabling percutaneous aspiration or tissue core biopsy of lesions.

Use of ultrasonography and secondary wound closure to facilitate diagnosis and treatment of a cranial mediastinal abscess in a dog.

A 3-year-old dog was examined because of acute, severe respiratory distress. Harsh inspiratory sounds, oral abrasions, and pyrexia were identified. On thoracic and cervical radiographs, the trachea appeared to be ventrally displaced and narrowed for several centimeters of its length at the thoracic inlet. Cytologic examination of a transcutaneous aspirate from the caudal cervical region revealed a neutrophilic exudate with extracellular bacteria. The ultrasonographic appearance of the thoracic inlet lent support to a diagnosis of cranial mediastinal abscess. Drainage and debridement of the abscess was accomplished via a ventral midline cervical approach, and the site was managed as an open wound. After 6 days, secondary wound closure was performed. The ventral cervical approach prevented contamination of the pleural space, and treatment as an open wound allowed inspection of the affected tissues to determine optimal time for wound closure. The cause of this cranial mediastinal abscess was unknown.

Aspergillosis granuloma in the mediastinum of a non-immunocompromised horse.

A National Show Horse with a mediastinal granuloma was presented with clinical signs which included fever, nasal discharge and cough. The mediastinal mass was identified radiographically and ultrasonographically. A presumptive diagnosis of aspergillosis was made following isolation of Aspergillus spp. from both transtracheal aspirate and bronchoalveolar lavage fluid samples and agar gel immunodiffusion (AGID) identification of serum antibody to Aspergillus spp. The diagnosis was confirmed by histopathologic examination of the mediastinal mass obtained at necropsy examination.