Search PubMedSearch

Biomedical subjects

R T O'Brien

Publications and source records attributed to R T O'Brien.

69 records · Page 4Linked to original sources

Quantitative ultrasonography of the liver in cats during obesity induction and dietary restriction.

A study was designed to evaluate quantitative ultrasonographic characteristics of a diffuse parenchymal disease in an experimental model of subclinical fatty infiltration of the liver using diet-induced obesity and dietary restriction in the cat. Ultrasound images of livers were quantitatively analysed by a video signal analysis technique before, during and at the end of obesity induction, and then during and following dietary restriction. Attenuation and brightness (backscatter coefficient) were correlated with hepatic lipid content obtained from the livers by surgical and ultrasound-guided percutaneous biopsy. Attenuation and backscatter increased as hepatic lipid content increased. Both attenuation and backscatter significantly correlated with the hepatic lipid content (P=0.002 and P=0.02 respectively). This model of subclinical fatty infiltration of the liver in the cat demonstrates that hepatic lipid content increases as a consequence of obesity and of severe dietary restriction. Infiltration of the liver with fat may be evaluated non-invasively using quantitative ultrasonography by the video signal analysis technique. This method of image analysis may prove useful for the evaluation of diffuse parenchymal organ disease.

Animals

Qualitative ultrasonography of the liver in obese cats.

A prospective study was undertaken to compare the relative echogenicity of the liver and the fat of the falciform ligament in two groups of clinically normal obese cats. In the first group of cats, four of eight normal weight cats were fed a high calorie diet ad libitum for a 12 week period at which time they were considered obese. The liver was hyperechoic when compared to the adjacent fat of the falciform ligament in the obese cats. In the second group of cats, the body condition of a group of eight clinically normal cats was subjectively graded. On ultrasonographic examination, the liver of those cats considered to be overweight were hyperechoic compared to the adjacent fat of the falciform ligament. Results from this study suggest that clinically normal obese cats may have a liver that is hyperechoic relative to the fat of the falciform ligament.

Adipose Tissue

Sonographic renal findings in 20 dogs with leptospirosis.

Abdominal ultrasound examinations of 20 dogs with confirmed leptospirosis were reviewed retrospectively for renal abnormalities. Three dogs had a normal ultrasound examination. The remaining 17 dogs had sonographic abnormalities of the kidneys. These abnormalities, seen either alone or in combination, included renalmegaly (n=10), pyelectasia (n=9), increased cortical echogenicity (n=15), perinephric effusion (n=5), and a medullary band of increased echogenicity (n=6). At our institution, the medullary band of increased echogenicity has only been seen in dogs with leptospirosis and may therefore be a specific sonographic sign for this disease.

Animals

Urinary bladder mural hemorrhage associated with systemic bleeding disorders in three dogs.

The sonographic appearance of three dogs with diffuse bladder wall thickening due to mural hemorrhage is described. Two dogs were diagnosed with immune-mediated thrombocytopenia and the third dog with vitamin K antagonist toxicity. Urinary bladder wall thickening ranged from 5 to 12 mm on initial sonographic examination. In the two surviving dogs, the bladder wall returned to normal thickness. One dog, euthanatized for refractory hematuria, had submucosal hemorrhage in the urinary bladder at necropsy. Urinary wall thickening sonographically resolved at a rate of approximately 1 mm per day. Mural hemorrhage should be considered in patients with concurrent bleeding disorder and urinary bladder wall thickening.

Animals

Ultrasound-guided fine-needle aspiration of focal parenchymal lesions of the lung in dogs and cats.

Ultrasound-guided fine-needle aspiration (FNA) of the lung was performed on 16 dogs and 3 cats with consolidated pulmonary lesions or masses identified on thoracic radiographs. The cytologic results from the FNA were confirmed by histopathology, response to treatment, or microscopic identification of Blastomyces organisms. Neoplasia was identified correctly by FNA cytology in 10 of 11 animals, and no false positive results occurred, yielding a positive predictive value of 100%. Of 8 animals with infectious disease, 5 of 6 had blastomycosis and 1 had a bacterial infection, based on cytologic evaluation. Eight animals required sedation for the procedure, and none had clinical complications. We conclude that ultrasound-guided FNA of pulmonary mass lesions is an inexpensive, safe, and accurate method for diagnosing blastomycosis or neoplasia, especially carcinomas, in dogs and cats.

Animals

Dynamic ultrasonographic measurement of passive coxofemoral joint laxity in puppies.

A new method of dynamic ultrasonographic evaluation of passive coxofemoral joint laxity was used to examine a total of 30 greyhound (n = 13) and nongreyhound (n = 17) puppies. Puppies were evaluated sonographically at four, six, eight, 12, 16, and 26 weeks of age. The coxofemoral joints were distracted manually, and the femoral head displacements were measured during distraction. The greyhounds had significantly smaller (p less than 0.01) maximum distraction distance (mean +/- standard deviation [SD], 0.11 +/- 0.04 cm) than nongreyhound puppies (mean +/- SD, 0.26 +/- 0.10 cm). In six- to eight-week-old puppies, the maximum distraction distance was correlated significantly (p of 0.0001, adjusted correlation coefficient [r2] of 0.27) with stress radiographic indices. Coxofemoral joints interpreted as being abnormal on hip-extended radiographs taken at one year of age were associated significantly (p of 0.0001) with higher maximum distraction distances in six- to eight-week-old puppies.

Analysis of Variance

Early detection of canine hip dysplasia: comparison of two palpation and five radiographic methods.

Hip joint laxity was evaluated in four breeds (i.e., greyhound, Labrador retriever, Irish setter, hound mixed-breed) of puppies (n=32) by Ortolani's and Bardens' maneuvers, by subjective assessment of radiographs (Orthopedic Foundation for Animals [OFA] method), and by four radiographic measurement indices. Puppies were studied at four, six-to-10, 16-to-18, and 52 weeks of age. The purpose of this study was to compare palpation and radiographic methods of hip laxity detection in puppies for predicting the development of degenerative joint disease (DJD) by one year of age. Twenty-seven (42%) hips developed DJD. Ortolani's method was not a reliable predictor of hip dysplasia at six-to-10 weeks; it was significantly predictive at 16-to-18 weeks but had a high incidence of false negatives. Bardens' and subjective (OFA) assessment methods were not reliable at six-to-10 or 16-to-18 weeks. Radiographic measurements taken with femurs in a neutral position and hips distracted (distraction index [DI] and Norberg angle) and measurements taken with femurs extended in OFA position (Norberg angle) of six- to 10-week-old puppies accurately predicted DJD occurrence by one year of age (p less than 0.01). Distraction index measurement (PennHIP method) was the most accurate in predicting the development of DJD (p less than 0.001). Distraction index radiography in puppies six-to-10 and 16-to-18 weeks of age was the most reliable predictor of hip dysplasia. Norberg angle measurement was more reliable during hip distraction than when hips were measured in the OFA position in 16- to 18-week-old puppies, but had similar reliability in six- to 10-week-old puppies.

Age Factors