Caudal mediastinal thyroglossal duct cyst in a cat.

An eight-year-old domestic shorthair cat was evaluated because of dyspnoea secondary to pleural effusion. Ultrasound examination identified a large anechoic cyst-like structure in the caudal thorax. A median sternotomy was performed, and the cystic mass was removed. Microscopically, the excised tissue was identified as a multilocular thyroglossal duct cyst with ectopic thyroid tissue. To the authors' knowledge, this is the first report of a mediastinal thyroglossal duct cyst in a cat. Despite the rarity of this lesion, it should be considered when a cystic thoracic structure is identified on thoracic ultrasound. Surgical excision of the cyst resulted in complete resolution of the pleural effusion and clinical signs.

Quantitative assessment of surgically induced mitral regurgitation using radionuclide ventriculography and first pass radionuclide angiography.

Radionuclide ventriculography has been used in humans to evaluate valvular incompetency. The stroke volume ratio, derived from the radionuclide ventriculogram, is used to quantify the severity of mitral regurgitation (MR). Previous studies conducted in humans have shown that left to right stroke volume ratio increases as the severity of MR increases. In this study, we evaluated radionuclide ventriculography as a noninvasive method to detect MR in dogs with surgically created mitral insufficiency. Six male and three female adult, conditioned mongrel dogs were used. Scintigraphic studies were performed prior to and 4 weeks after surgically created MR. Because of the overlap of the left and right ventricles when viewed from a left lateral position, we combined data from a first-pass radionuclide angiocardiogram with the radionuclide ventriculogram to obtain a corrected stroke volume ratio. Blood flow transit parameters were also derived from the first-pass radionuclide angiocardiogram. Standard left ventricular functional indices were also measured from the radionuclide ventriculogram. On the left lateral view of the heart, 25 to 30% of the right ventricular volume overlaps the left ventricle. After correcting for the overlap, the stroke volume ratio of normal dogs was 1.17+/-0.178 (mean+/-SD), which increased to 2.06+/-0.41 (mean+/-SD) (p < .001) 4 weeks after creation of MR. The was no significant change in left ventricular ejection fraction or peak rate of ejection following MR. The transit times of blood through the left ventricle were measured from the first-pass radionuclide angiocardiogram and were expressed as half-time clearance, peak clearance rate, and time to peak clearance rate. The baseline half-time clearance was 2.07+/-0.71 s (mean+/-SD), which increased to 6.70+/-4.89 s (mean+/-SD) (p = .02) after creation of MR. The baseline peak clearance rate was 49.75+/-8.96 cts/s (mean+/-SD), which decreased to 23.12+/-6.84 cts/s (mean+/-SD) (p < .001) after creation of MR. Stroke volume ratios significantly increased following creation of MR. Blood flow transit through the left ventricle slowed following creation of MR. The variability of these parameters were small in the baseline studies, suggesting these techniques may be clinically useful to gauge the severity of MR in dogs.

Short-term hemodynamic evaluation of circumferential mitral annuloplasty for correction of mitral valve regurgitation in dogs.

OBJECTIVE: To determine the short-term hemodynamic effects associated with circumferential mitral annuloplasty (CMA) in dogs with mitral regurgitation. STUDY DESIGN: Prospective experimental study. Animals-Seven healthy adult mongrel dogs. METHODS: Mitral regurgitation was surgically induced, and annular dilation occurred. Echocardiography and cardiac catheterization were used to determine forward ejection fraction (FEF), regurgitant fraction (RF), pulmonary capillary wedge pressure (PCWP), and annular diameter before and immediately after CMA in five dogs. FEF and RF were also evaluated 7 days after annuloplasty. RESULTS: Mean annular diameter and PCWP were significantly reduced immediately after CMA. Significant increases in FEF of 19% and 22% were shown immediately and 7 days after CMA. Significant reductions in RF of 19% and 22% were also shown immediately and 7 days after annuloplasty. CONCLUSIONS: Sustained hemodynamic benefits and a reduction in annular diameter were achieved by CMA in a canine model of mitral regurgitation. CLINICAL IMPLICATIONS: CMA may be a suitable treatment for heart failure because of mitral regurgitation when early signs of cardiovascular decompensation persist despite appropriate medical management.

Pericardiectomy in dogs: 22 cases (1978-1994).

OBJECTIVE: To determine long-term outcome of dogs with neoplastic and nonneoplastic pericardial disease that undergo pericardiectomy. DESIGN: Retrospective study. ANIMALS: 22 dogs. PROCEDURE: Dogs that underwent pericardiectomy and in which the diagnosis had been confirmed histologically were included. Data collected from each record included signalment, history, clinical signs, results of diagnostic evaluations, operative management, postoperative complications, histologic diagnosis, and outcome. Dogs were grouped on the basis of underlying cause of pericardial disease (neoplastic vs nonneoplastic), and survival times were determined by means of Kaplan-Meier analyses. RESULTS: 9 dogs had neoplastic pericardial disease (chemodectoma, 4; hemangiosarcoma, 2; malignant mesothelioma, 2; lymphoblastic lymphoma, 1). Thirteen dogs had nonneoplastic pericardial disease (benign idiopathic pericarditis, 10; lymphocytic plasmacytic pericarditis, 2; osseous metaplasia of unknown cause, 1). Thoracic radiography and echocardiography were the most specific methods for diagnosis of pericardial effusion. Pleural effusion was the most common postoperative complication (8/22 dogs). Prevalence of postoperative complications was not associated with underlying cause of pericardial disease, surgical approach, or surgical procedure (subtotal vs total pericardiectomy). Median survival time of dogs with neoplastic disease (52 days) was significantly shorter than median survival time of dogs with nonneoplastic disease (792 days). Dogs that developed pleural effusion > 30 days after pericardiectomy had a poor prognosis for survival. CLINICAL IMPLICATIONS: Radiography and echocardiography are useful for diagnosis of pericardial effusion in dogs. Dogs with neoplastic pericardial disease have a significantly shorter survival time than do dogs with nonneoplastic pericardial disease.