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Biomedical subjects

W P Thomas

Publications and source records attributed to W P Thomas.

At least 19 recordsLinked to original sources
PubMed1993

Cor triatriatum dexter in two dogs.

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.

Animals↗
PubMed1992

Clinical findings in cats with dilated cardiomyopathy and relationship of findings to taurine deficiency.

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.

Animal Feed↗
PubMed1992

Response of cats with dilated cardiomyopathy to taurine supplementation.

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.

Animal Feed↗
PubMed1987

Effects of simultaneous viewing and vaporization of plaques using the steerable, laser-heated metal cap in the atherosclerotic monkey model.

A steerable, fiberoptic catheter coupled to a laser light guide tipped with a metal cap was used. Four monkeys fed an atherogenic diet for 7-8 years were angiographed and were found to have extensive mural plaque in the iliac arteries. Plaque sites in these monkeys were vaporized using the laser-heated metal cap. Energies of 1.5-9 Joules were employed. Application of the energy was tangential of perpendicular to the plaque. Lased sites were examined histologically at 24 hr or at 3 months after treatment. No effect was seen at 1.5 Joules. Three to six Joules tangentially produced a superficial lesion that extended into the tunica intima. Six Joules perpendicularly produced a burn into the tunica adventitia, with damage to the vasavasorum. Nine Joules tangentially produced a burn into the tunica media. Three months after treatment, this lased site showed no stenosis or aneurysm formation.

Animals↗
PubMed1987

Idiopathic effusive pericarditis with tamponade in the horse.

Pericarditis and pericardial effusion are considered to occur rarely in the horse. The clinical and laboratory features of idiopathic pericarditis with effusion diagnosed in 10 horses over a seven-year period were reviewed. Consistent physical findings included tachycardia, ventral oedema, jugular venous distention and diminished heart sounds. Electrocardiographic features included diminished voltages and electrical alternans, and the effusion was identified by echocardiography in the six horses in which it was performed. Pericardiocentesis relieved clinical signs in nine horses. Laboratory analysis of pericardial fluid samples classified six cases as aseptic serofibrinous, three cases as eosinophilic, and one case as histiocytic. One horse died and three were destroyed. The remaining six horses recovered following pericardiocentesis (performed once or twice) with or without corticosteroid treatment, and were alive one month to seven years after diagnosis.

Animals↗
PubMed1987

Systemic and pulmonary haemodynamics in normal neonatal foals.

Cardiopulmonary function was studied in 10 full-term healthy foals from birth to 14 days of age. Systemic and pulmonary haemodynamics were recorded in lateral recumbency via indwelling aortic and pulmonary artery catheters. Mean body weight increased from 45.4 +/- 2.4 kg on Day 1 to 70.6 +/- 6.1 kg on Day 14. All foals had a continuous murmur of patent ductus arteriosus for 3-6 days. From Day 1 (12 h old) to Day 14, heart rate increased (89 +/- 4 to 95 +/- 5/min), mean aortic pressure increased (87.7 +/- 1.9 to 100.3 +/- 3.2 mmHg), mean pulmonary artery pressure decreased (38.6 +/- 4.6 to 27.4 +/- 3.0 mmHg), mean right atrial pressure was unchanged (4.5 +/- 0.5 to 4.6 +/- 0.9 mmHg), mean pulmonary artery wedge pressure was unchanged (7.6 +/- 0.9 mmHg to 8.1 +/- 0.7 mmHg), cardiac output increased (8.03 +/- 0.59 to 15.88 +/- 1.90 l/min), cardiac index increased (180.5 +/- 10.3 to 222.1 +/- 21.6 ml/kg/min), stroke volume increased (90.4 +/- 5.7 to 164.2 +/- 25.9 ml), stroke volume index was unchanged (2.04 +/- 0.10 to 2.30 +/- 0.35 ml/kg), pulmonary vascular resistance decreased (314 +/- 39 to 104 +/- 21 aru), systemic vascular resistance decreased (858 +/- 70 to 497 +/- 87 aru), and pulmonary/systemic resistance ratio decreased (38 +/- 6 to 21 +/- 5%). All changes were gradual, although pulmonary artery pressure and pulmonary vascular resistance decreased rapidly in the first 24 h. Catheters were well tolerated over several days, indicating their feasibility for studying cardiovascular function in full-term or premature equine neonates.

Animals↗
PubMed1985

Sensitivity and specificity of the indirect-fluorescent antibody test and two enzyme-linked immunosorbent assays in canine dirofilariasis.

Ninety dogs naturally infected with Dirofilaria immitis and 103 noninfected dogs, as determined by necropsy, were used to compare the sensitivity and specificity of the cuticular and somatic reactions of the indirect fluorescent antibody test (IFA-C and IFA-S, respectively) and 2 enzyme-linked immunosorbent assays (ELISA). In microfilaremic and amicrofilaremic heartworm-infected dogs, negative results were common for all serotests. In dogs without adult heartworms at necropsy, 32% to 49% were positive, using 1 ELISA, 27% to 29% were positive with the other ELISA, 15% to 36% were positive with the IFA-S, and 0% to 1% were positive using the IFA-C, depending on the classification of borderline reactions. The prevalence of false positive serotests was probably not due to the detection of precardial stages of D immitis in dogs obtained from areas of low endemicity. Until the causes of the false-positive tests are resolved, the use of currently available serotests for routine diagnostic screening or as criteria for instituting treatment is not recommended.

Animals↗
PubMed1984

Constrictive pericardial disease in the dog.

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.

Animals↗
PubMed1984

Endocarditis of the aortic valve in the dog.

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.

Animals↗
PubMed1984

Diagnostic value of pericardial fluid analysis in the dog.

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.

Adenocarcinoma↗
PubMed1984

Hemodynamics of progressive pneumopericardium in the dog.

The hemodynamics of progressive pneumopericardium were studied in 6 anesthetized healthy dogs (with intact thorax). Heart rate, cardiac output, and pericardial and intravascular pressures were recorded. Pressures were measured in the pericardial space by means of a percutaneously introduced, air-filled catheter, and in the right atrium, right ventricle, left atrium, left ventricle, pulmonary artery, and aorta by means of fluid-filled catheters. The gradual increase in mean pericardial pressure up to 11 +/- 2 mm of Hg was associated with increases in heart rate and mean right atrial, mean left atrial, right ventricular end-diastolic, and left ventricular end-diastolic pressures and with decreases in cardiac output and stroke volume, with no change in left ventricular systolic and mean aortic pressures. Critical cardiac tamponade occurred at a pericardial pressure of 12.2 +/- 2.8 mm of Hg, which was produced by 8.7 +/- 1.9 cm3 air/kg of body weight. This was characterized by a sudden marked decrease in heart rate, cardiac output, stroke volume, left ventricular systolic pressure, and mean aortic pressure, and equilibration of mean right atrial, mean left atrial, right ventricular end-diastolic, left ventricular end-diastolic, and pulmonary artery diastolic pressures. These hemodynamic changes were similar to those of experimental pericardial effusion.

Animals↗
PubMed1983

A pharmacokinetic study of digoxin in the horse.

Digoxin was administered orally and intravenously to seven healthy adult mares and geldings in two separate trials. At a dose of 44 microgram digoxin/kg body weight, the oral study was characterized by an absorption phase with a mean (+/- 1 standard deviation) peak serum digoxin concentration of 2.21 ng/ml (+/- 0.45) at a mean of 2.29 h (+/- 1.52) after administration. A second rise in serum digoxin concentration started about 6-8 h after administration and extended to about 20 h after administration. The mean bioavailability (F) was 23.38% (+/- 5.96). At a dose of 22 microgram digoxin/kg body weight, the intravenous study was characterized by a two-compartment model with the following mean pharmacokinetic measurements: distribution rate constant (alpha), 1.391 h-1 (+/- 0.1909); zero-time serum digoxin concentration determined from the distribution phase (A), 21.247 ng/ml (+/- 5.6614); elimination rate constant (beta), 0.0409 h-1 (+/- 0.0069); zero-time serum digoxin concentration determined from the elimination phase (B), 3.82 ng/ml (+/- 0.433); apparent specific volume of distribution uncorrected for protein binding (Vd beta), 5.003 l/kg (+/- 0.5177). The mean beta corresponded to a biological half-life (T1/2 beta) of 16.9 h. Based upon results of this study, theoretically achievable steady-state serum digoxin concentrations were calculated for maintenance doses given by oral and intravenous routes of administration with appropriate two-compartment, multiple-dose formulae. Loading doses were also calculated for each route. It is the opinion of the authors that the oral route of administration of digoxin is effective in the horse and may preclude the potential risks posed by the high serum digoxin concentrations immediately following intravenous administration.

Administration, Oral↗
PubMed1982

Medical management of congestive heart failure in a horse.

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.

Administration, Oral↗
PubMedDate not supplied

Biplane transesophageal echocardiography in the normal cat.

Eight healthy, adult cats were examined with biplane transesophageal echocardiography (TEE). Cats were sedated with a combination of diazepam and propofol and were examined using a 5 mm x 80 cm pediatric biplane TEE probe. Consistent images were obtained at three imaging depths within the esophagus. The caudal position provided satisfactory short-axis images of the left ventricle and heart base. The middle position provided the best long-axis views of the left atrium, left ventricle, and aorta and allowed Doppler examination of transmitral left ventricular inflow. The cranial position provided satisfactory imaging of the aorta and pulmonary artery and allowed Doppler examination of right ventricular and left ventricular outflow. Biplane TEE provides an additional method of imaging the feline heart which is complimentary to other imaging techniques and the images obtained were similar to those reported for dogs. Although TEE offers a slight advantage over transthorcic imaging for Doppler examination, the quality of the images of heart base structures was not as consistently superior to transthoracic images in cats as reported in dogs.

Animals↗
PubMedDate not supplied

Pulmonary lymphomatoid granulomatosis in seven dogs (1976-1987).

Seven dogs with pulmonary lymphomatoid granulomatosis were reviewed. The disease occurred in six large-breed and one small-breed dogs. The dogs were five to 14 years old (mean, 8.4; median, 7), and four of seven dogs were males. Three dogs had been previously treated with adulticide therapy for canine dirofilariasis. Clinical histories included a progressive respiratory disease characterized by varying degrees of cough, dyspnea, exercise intolerance, and weight loss. Thoracic radiographic features included hilar lymphadenopathy, pulmonary masses of varying sizes, and mixed pulmonary patterns of lobar consolidation with ill-defined interstitial and alveolar pulmonary infiltrates. Cardiovascular changes compatible with chronic dirofilariasis were present in three dogs. The clinical course was usually progressive and fatal. The survival time ranged from six days to four years (mean, 12.5 mos; median, 3 mos). Gross and histologic features included mass lesions with areas of necrosis that replaced normal pulmonary architecture. Cytologically, these lesions were characterized by infiltration with pleomorphic, angioinvasive mononuclear cells that often resulted in vascular obliteration. The infiltrating cells resembled large lymphoid cells that possessed large hyperchromatic nuclei and small amounts of cytoplasm. Systemic lymphoid neoplasia with peripheral lymphadenopathy was diagnosed in two dogs. In both cases, lymph-node cytology was similar to the cellular infiltrates found in the lungs and consistent with a diagnosis of lymphomatoid granulomatosis. These features are compared with previously reported cases of canine lymphomatoid granulomatosis and those features identified in a similar disease described in man.

Animals↗