Serological, reverse transcriptase-polymerase chain reaction, and immunohistochemical detection of West Nile virus in a clinically affected dog.

Necropsy of an older dog submitted for evaluation of renal and central nervous system disease revealed histologic lesions compatible with West Nile viral encephalitis and myocarditis, as seen in other species. Using reverse transcriptase-polymerase chain reaction detection of envelope sequences, viral RNA was detected in most organs, and quantitative polymerase chain reaction revealed that at least 1,000 times more RNA was present in kidney than in brain, heart, spleen, or lung. Immunohistochemical evaluation of the kidney revealed intense staining of West Nile viral antigens in renal tubular epithelium and casts located within multifocal granulomatous interstitial inflammation. A canine immunoglobulin M (IgM)-capture enzyme-linked immunosorbent assay was developed, and patient serum was strongly positive for viral antibody. Retrospective and ongoing evaluation of sera from dogs with neurological disease and of those submitted for heartworm testing detected 4 dogs that were subclinically infected but without additional sickness. Judged by this experience, the kidney of West Nile virus-infected dogs may be an important target organ, one that might be suitable for antemortem biopsy. The presence of virus-specific IgM was demonstrated in the serum of this dog, and finding 4 positives among 169 additional canine sera received since late July 2002 suggests that seroconversion appears to be relatively uncommon in dogs during the outbreak in Missouri.

Congestive heart failure in horses: 14 cases (1984-2001).

OBJECTIVE: To identify clinical signs, underlying cardiac conditions, echocardiographic findings, and prognosis for horses with congestive heart failure. DESIGN: Retrospective study. ANIMALS: 14 horses. PROCEDURE: Signalment; history; clinical signs; clinicopathologic, echocardiographic, and radiographic findings; treatment; and outcome were determined by reviewing medical records. RESULTS: All 14 horses were examined because of a heart murmur; tachycardia was identified in all 14. Twelve horses had echocardiographic evidence of enlargement of 1 or more chambers of the heart. Other common clinical findings included jugular distention or pulsation, crackles, cough, tachypnea, and ventral edema. Nine horses had signs consistent with heart failure for > 6 days. Underlying causes for heart failure included congenital defects, traumatic vascular rupture, pericarditis, pulmonary hypertension secondary to heaves, and valvular dysplasia. Seven horses were euthanatized after diagnosis of heart failure; 5 were discharged but were euthanatized or died of complications of heart disease within 1 year after discharge. The remaining 2 horses were discharged but lost to follow-up. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that congestive heart failure is rare in horses. A loud heart murmur accompanied by either jugular distention or pulsation, tachycardia, respiratory abnormalities (crackles, cough, tachypnea), and ventral edema were the most common clinical signs. Echocardiography was useful in determining the underlying cause in affected horses. The long-term prognosis for horses with congestive heart failure was grave.