Comparison of presumptive echocardiographic and definitive diagnoses of cardiac tumors in dogs.

BACKGROUND: Echocardiography is used for identification of cardiac tumors and presumptive diagnoses often are made based on the location of identified masses. OBJECTIVES: To determine the accuracy of echocardiographically based presumptive diagnoses of cardiac tumors when compared with clinicopathologic or histopathologic definitive diagnoses. ANIMALS: A total of 24 client-owned dogs having a cardiac mass on echocardiogram that was subsequently definitively diagnosed by cytology or histopathology. METHODS: Retrospective study. A Cardiac Veterinary Database search of animals seen at the University of Tennessee John and Ann Tickle Small Animal Hospital from 2006 to 2012 identified 24 dogs that fit the inclusion criteria. RESULTS: The presumptive diagnosis of chemodectoma, ectopic thyroid carcinoma, or lymphoma in cases with heart base masses was correct in 7/9 cases. The presumptive diagnosis of hemangiosarcoma in cases with right atrial masses was correct in 4/8 cases. Seven cases had an open diagnosis because of the unusual presentation on echocardiogram (ECG); various neoplasms were diagnosed in these animals, but hemangiosarcoma, chemodectoma, ectopic thyroid carcinoma, and lymphoma accounted for 6 of them. Pericardial effusion was seen in 10/24 cases. ECG abnormalities were seen in 8/24 cases. Survival ranged from <1 to >150 days. CONCLUSIONS AND CLINICAL IMPORTANCE: In this retrospective study, the presumptive diagnosis based on echocardiographic tumor location was only moderately accurate. Cardiac tumors that were considered unusual on echocardiogram were nonetheless frequently found to be the common cardiac tumor types seen in dogs.

The effects of pentoxifylline on equine platelet aggregation.

BACKGROUND: Pentoxifylline (PTX) possesses a number of vasomotor, immunomodulatory, and hemorheologic properties. Based upon the hypothesis that equine laminitis and navicular disease result from microthrombosis, the inhibitory effects of PTX on inflammatory cytokines, and its inhibitory effects on human platelet aggregation, PTX has been widely used to treat equine endotoxemia, navicular disease, and laminitis. Despite this, the effects of PTX on equine platelet aggregation have not been investigated previously. HYPOTHESIS: PTX decreases platelet aggregation in equine whole blood at concentrations approximating those achieved in horses given clinically relevant doses of PTX. ANIMALS: Seven healthy adult horses from a research herd. METHODS: Whole blood impedance aggregometry using whole equine blood incubated with varying concentrations of PTX. Adenosine diphosphate (ADP) and collagen were used to initiate aggregation. RESULTS: The onset time of collagen-induced equine platelet aggregation was significantly shortened by PTX. The maximum slope of resistance change (dR/dt) and total resistance change of collagen-induced platelet aggregation were unaffected by PTX. No effects of PTX on ADP-induced onset time of aggregation, dR/dt, or total resistance change were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: Our hypothesis is not supported by the results. PTX hastens the onset of collagen-induced platelet aggregation in equine whole blood, but has no effect on the rate of collagen-induced aggregation. PTX does not affect ADP-dependent equine platelet aggregation. Given these findings, PTX may not be a reasonable therapeutic option to decrease platelet aggregation in horses.

Combination therapy with digoxin and diltiazem controls ventricular rate in chronic atrial fibrillation in dogs better than digoxin or diltiazem monotherapy: a randomized crossover study in 18 dogs.

BACKGROUND: Atrial fibrillation (AF) with excessively high ventricular rates (VR) occurs in dogs with advanced heart disease. Rate control improves clinical signs in these patients. Optimal drug therapy and target VR remain poorly defined. HYPOTHESIS: Digoxin-diltiazem combination therapy reduces VR more than either drug alone in dogs with high VR AF. ANIMALS: Eighteen client-owned dogs (>15 kg) with advanced heart disease, AF, and average VR on 24-hour Holter > 140 beats per minute (bpm). METHODS: After baseline Holter recording, dogs were randomized to digoxin or diltiazem monotherapy, or combination therapy. Repeat Holter evaluation was obtained after 2 weeks; dogs were then crossed over to the other arm (monotherapy or combination therapy) for 2 weeks and a third Holter was acquired. Twenty-four hour average VR, absolute and relative VR changes from baseline, and percent time spent within prespecified VR ranges (>140, 100-140, and <100 bpm) were compared. Correlations between serum drug concentrations and VR were examined. RESULTS: Digoxin (median, 164 bpm) and diltiazem (median, 158 bpm) decreased VR from baseline (median, 194 bpm) less than the digoxin-diltiazem combination (median, 126 bpm) (P < .008 for each comparison). With digoxin-diltiazem, VR remained <140 bpm for 85% of the recording period, but remained >140 bpm for 88% of the recording period with either monotherapy. Serum drug concentrations did not correlate with VR. CONCLUSIONS AND CLINICAL IMPORTANCE: At the dosages used in this study, digoxin-diltiazem combination therapy provided a greater rate control than either drug alone in dogs with AF.

Effect of transvenous electrical cardioversion on plasma cardiac troponin I concentrations in horses with atrial fibrillation.

BACKGROUND: Whether electrical cardioversion of cardiac arrhythmias results in cardiomyocyte damage is unknown. OBJECTIVE: To describe effect of transvenous electrical cardioversion (TVEC) on plasma cardiac troponin I (cTnI) concentration in horses. ANIMALS: All horses presented to the Cornell University Hospital for Animals for cardioversion of atrial fibrillation between May 2006 and October 2008 were eligible for inclusion in the study. Owners of 14 horses elected for TVEC and each horse was then enrolled (16 procedures). METHODS: Prospective observational study measuring concentrations of plasma cTnI before and after TVEC. RESULTS: Median cTnI concentration increased from 0.045 ng/mL at baseline (range 0.0-0.20 ng/mL) to 0.11 ng/mL after TVEC (range 0.0-3.73 ng/mL) (P= .036). This increase was not associated with the number of shocks delivered, maximal energy delivered, cumulative energy delivered, chronicity of atrial fibrillation before cardioversion, or positioning of the pulmonary artery catheter. CONCLUSIONS: The increase in cTnI is unlikely to be clinically important. The increase might be correlated with persistent atrial dysfunction after TVEC, suggesting that a longer convalescent period after the procedure could be warranted.

Temperature-sensitive mutants with lesions in the vaccinia virus F10 kinase undergo arrest at the earliest stage of virion morphogenesis.

Vaccinia virus encodes two protein kinases; the B1 kinase is expressed early and appears to play a role during DNA replication, whereas the F10 kinase is expressed late and is encapsidated in virions. Here we report that the F10 kinase gene is the locus affected in a complementation group of temperature-sensitive mutants composed of ts15, ts28, ts54, and ts61. Although these mutants have a biochemically normal phenotype at the nonpermissive temperature, directing the full program of viral gene expression, they fail to form mature virions. Electron microscopic analysis indicates that morphogenesis undergoes arrest at a very early stage, prior to the formation of membrane crescents or immature virions. An essential role for the F10 protein kinase in orchestrating the onset of virion assembly is implied.