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A 13-year-old Oldenburg mare was evaluated for lethargy and signs of mild colic. Pericardial tamponade caused by fibrinoeffusive pericarditis was diagnosed. Cytologic and biochemical evaluation of pericardial fluid was consistent with a septic effusion. Corynebacterium pseudotuberculosis, the cause of pigeon fever, was identified by bacteriologic culture of pericardial fluid. Drainage and lavage of the pericardial sac, local (intrapericardial) and systemic antimicrobial treatment, and subsequent corticosteroid treatment resulted in a successful outcome in this horse. To the authors' knowledge, this is the first report of pericarditis associated with C pseudotuberculosis in a horse.

Cor triatriatum dexter is a congenital heart defect in which the embryologic right sinus venosus valve persists as a septum within the right atrium. Cor triatriatum dexter was diagnosed in 2 dogs on the basis of clinical signs, two-dimensional echocardiography, and cardiac catheterization. In 1 of the dogs, the condition was successfully treated by surgical resection of the intra-atrial septum. In the second dog, the defect was associated with an incomplete persistent cranial left vena cava and Ebstein's anomaly; surgery was declined.

Between October 1986 and September 1988, 37 cats with moderate to severe idiopathic myocardial failure (dilated cardiomyopathy) were evaluated prospectively. Low plasma taurine concentration and diet history including foods that can cause taurine deficiency were documented in most of the cats. Comparison with a retrospectively studied population of 33 cats with dilated cardiomyopathy diagnosed between 1980 and 1986 demonstrated that the clinical and historical findings in the 33 retrospectively studied cats were similar to those in the 37 cats studied prospectively. Clinical findings in the 2 groups were also similar to findings previously reported in the literature. Because clinical findings and diet history were similar in the prospective and retrospective groups, we believe that many cats in the latter group had diet-induced taurine deficiency. These findings support the conclusion that most cases of dilated cardiomyopathy in cats have a common etiopathogenesis related to diet and as such are preventable.

Between October 1986 and September 1988, 37 cats with moderate to severe idiopathic myocardial failure (dilated cardiomyopathy) were evaluated. Clinical management of these cats was similar to that described in the literature, except that it also included administration of 500 or 1,000 mg of the sulfur amino acid, taurine per day. Early death (death within the first 30 days of treatment) occurred in 14 (38%) cats. One cat was lost to follow-up evaluation. Twenty-two cats (59%) had marked clinical and echocardiographic improvement and survived longer than 240 days. In all but 1 cat, the observed improvement in echocardiographic measurements persisted. Hypothermia and thromboembolism were positively associated with an increased risk of early death. Administration of digoxin did not significantly affect survival. All 22 cats that survived greater than 30 days remained clinically stable despite withdrawal of all medications except taurine. Administration of taurine was eventually discontinued in 20 of the 22 cats and adequate taurine intake was thereafter provided for in the food. The clinical response and 1-year survival rate of 58% (21 of 36 cats with a known outcome) in the taurine-treated group represents a marked improvement, compared with a 1-year survival rate of 13% (4 of 31 cats with a known outcome) in a retrospectively evaluated population of 33 cats with dilated cardiomyopathy.

The clinicopathologic features of constrictive pericardial disease in 13 dogs were reviewed. The causes were infection (3 dogs), metallic foreign body (1 dog), and idiopathic (9 dogs). Owner complaints included abdominal enlargement, tachypnea, weakness or syncope, exertional fatigue, and weight loss. Ascites and jugular venous distention were consistently observed, whereas abnormalities of arterial pulses and heart sounds were variable and inconsistent. Diminished QRS voltages were common. Mild to moderate cardiomegaly, rounding of the cardiac silhouette, and variable and nonspecific angiographic findings were frequently observed. Cardiac catheterization consistently showed elevation and equilibration of atrial and ventricular diastolic pressures, but a prominent early diastolic (y) descent was uncommon. Fibrosis was confined to the parietal pericardium in 8 dogs, and included the epicardium in 5 dogs. Parietal pericardectomy was successful in relieving the syndrome in 6 of 10 dogs. Pulmonary thrombosis was the most common cause of early postoperative mortality.

A 4-year-old Quarter Horse gelding with atrial fibrillation, mitral regurgitation, and signs of bilateral congestive heart failure was initially treated IV with digoxin and furosemide. After parenteral digitalization, a daily maintenance dose of digoxin was administered orally at a rate of 21.7 micrograms/kg of body weight. At this dosage, a steady-state serum digoxin concentration of 2.3 ng/ml was achieved without clinical signs of toxicosis. The furosemide dosage was decreased and eventually discontinued as clinical improvement occurred. Clinical signs of congestive heart failure were controlled and sinus rhythm was intermittently established, but an unfavorable prognosis was given for future athletic work. After 35 days of therapy, cardiac catheterization was performed and the horse was euthanatized. At necropsy there was marked dilatation of all cardiac chambers, mitral valve fibrosis, and left atrial jet lesions. The response of this patient suggested that orally administered digoxin may be useful in the management of congestive heart failure in selected equine patients.

The physical, chemical, and cytologic characteristics of 50 pericardial effusions were reviewed to determine their value to the clinician for distinguishing a variety of pericardial disorders in the dog. Pericardial fluid analysis allowed identification of chylous and bacterial pericardial effusions. Overlap in the ranges of RBC counts, nucleated cell counts, and protein concentrations between dogs with neoplastic and nonneoplastic disorders precluded identification of the cause of the effusion. Of 19 neoplastic effusions, 74% were not detected on the basis of cytologic findings and 13% of 31 nonneoplastic effusates were falsely reported as positive or suspect for a neoplasm. It was concluded that pericardial fluid analysis, including cytologic examination, did not reliably distinguish neoplastic from nonneoplastic disorders.

The clinical features of endocarditis of the aortic valve in 24 dogs were reviewed. This condition was found most commonly in large-breed, middle-aged male dogs. Evidence of antecedent infection or immunosuppression was usually not historically verified or found at necropsy. However, an association with congenital heart disease, especially discrete subaortic stenosis, was demonstrated. The most frequent clinical findings were systolic and diastolic murmurs and bounding arterial pulses, with or without signs of congestive heart failure. The most commonly isolated organisms were Corynebacterium sp, Erysipelothrix rhusiopathiae, and Streptococcus sp. In addition to antibiotic therapy, treatment for congestive heart failure often was required. Despite aggressive therapy, most affected dogs died as a result of congestive heart failure, arrhythmias, infarction, sepsis, or renal failure.