Biomedical subjects

C A Osborne

Publications and source records attributed to C A Osborne.

At least 37 records · Page 2Linked to original sources

PubMed1999

Imaging canine urocystoliths. Detection and prediction of mineral content.

The role of survey radiography, contrast radiography, and ultrasonography in the assessment of urocystolithiasis has been primarily one of detection. Information about the radiographic characteristics of uroliths (size, shape, radiopacity, surface characteristics, number detected) for characterization and diagnosis of urocystolithiasis is emerging; however, there are no studies on the accuracy or sensitivity of these techniques. In this article, the intent is to update knowledge about available imaging techniques used in the detection and characterization of urocystoliths based on recent studies designed to evaluate their accuracy in prediction of different urocystoliths mineral content.

Animals↗

PubMed1999

Medical dissolution and prevention of canine struvite urolithiasis. Twenty years of experience.

Two types of canine struvite uroliths have been recognized: infection-induced struvite is the most common type; sterile struvite is uncommonly recognized. Infection-induced struvite is most commonly associated with urease-producing staphylococcal UTI. For dogs that qualify, medical dissolution is an effective method of treatment. Medical dissolution protocols encompass: (1) eradication or control of UTI; (2) use of calculolytic diets; and (3) administration of urease inhibitors to patients with persistent UTI caused by urease-producing microbes.

Animals↗

PubMed1999

Epidemiology of canine calcium oxalate uroliths. Identifying risk factors.

Calcium oxalate uroliths are most commonly encountered in Miniature Schnauzers, Lhaso Apsos, Yorkshire Terriers, Bichons Frises, Shih Tzus, and Miniature Poodles. They are more common in males than females, and more common in older than young dogs. Dogs that form abnormal nephrocalcin are also predisposed to calcium oxalate uroliths. Dietary risk factors for calcium oxalate uroliths include excessive calcium supplementation or excessive calcium restriction, excessive oxalic acid, high protein, high sodium, restricted phosphorus, restricted potassium, and restricted moisture (dry formulations). Dogs with hyperadrenocorticism or hypercalcemia are predisposed to calcium oxalate urolith formation.

Animals↗

PubMed1999

Canine calcium oxalate urolithiasis. Case-based applications of therapeutic principles.

The case study presented here illustrates the diagnosis and management of calcium oxalate urolithiasis in a Bichon Frise, a breed at increased risk for this type of stone. If the Bichon Frise had persistent hypercalcemia, we would have evaluated serum concentrations of ionized calcium, parathyroid hormone, and vitamin D to identify an underlying cause. Because his urine was alkaline, additional potassium citrate was not provided. Likewise, as a fortified diet was fed to him, vitamin B6 therapy was not considered. This case study illustrates the benefits of radiographic evaluation immediately following surgery and during follow-up examinations. If we had postponed radiographs until the patient developed clinical signs, additional surgical procedures may have been required.

Animals↗

PubMed1999

Canine calcium phosphate uroliths. Etiopathogenesis, diagnosis, and management.

Uroliths composed predominantly of calcium phosphates have been infrequently identified in dogs. Factors incriminated in the etiopathogenesis of calcium phosphate urolithiasis include an alkaline urine pH, hypercalciuria, decreased urine concentrations of crystallization inhibitors, and increased urine concentrations of crystallization promoters. Disorders associated with calcium phosphate urolith formation in dogs include primary hyperparathyroidism, hyperadrenocorticism, and idiopathic hypercalciuria. Medical therapy of patients with recurring calcium phosphate uroliths should be directed at removing or minimizing factors contributing to urine supersaturation with calcium phosphate.

Animals↗

PubMed1999

Canine urate urolithiasis. Etiopathogenesis, diagnosis, and management.

Etiopathologic factors predisposing to urate lithogenesis in Dalmatian and non-Dalmatian dogs represent diverse pathologic and/or physiologic processes involving purine nucleotide and ammonia synthesis, biodegradation, and excretion. Predisposing factors for urate urolith formation include hyperuricemia, hyperammonemia, hyperuricosuria, hyperammonuria, aciduria, and genetic predisposition. Medical therapy of dogs forming urate uroliths should be directed at modifying these predisposing factors through dietary modification, administration of allopurinol, and/or surgical correction of portovascular anomalies if present. The precise mechanisms resulting in urate urolith formation in dogs have not been determined.

Animals↗

PubMed1999

Canine cystine urolithiasis. Cause, detection, treatment, and prevention.

Cystine uroliths are a sequela to cystinuria, an inherited renal tubular defect in reabsorption of cystine and some other amino acids. At the Minnesota Urolith Center, 67 breeds of dogs were identified, including English Bulldogs, Dachshunds, Mastiffs, and Newfoundlands. In some dogs, the severity of cystinuria may decline with advancing age. Current recommendations for dissolution of cystine uroliths include various combinations of diet modification, diuresis administration of 2-MPG, and alkalinization of urine.

Animals↗

PubMed1999

Canine silica urolithiasis. Risk factors, detection, treatment, and prevention.

Uroliths containing 70% or greater silica comprise approximately 1% of the canine uroliths submitted to the Minnesota Urolith Center. Male dogs are far more commonly affected than females. In our series, 84 different breeds were affected. Currently available data suggest dietary factors play a role in their formation. Diagnosis is facilitated by the characteristic jackstone configuration of silica uroliths, but must be confirmed by quantitative analysis. Voiding urohydropropulsion or surgery are currently the most practical methods of removal of silica uroliths.

Animals↗

PubMed1999

Canine and feline nephrolithiasis. Epidemiology, detection, and management.

Calcium oxalate (39%) and struvite (33%) were the predominant mineral types in canine nephroliths submitted to the Minnesota Urolith Center. Urate salts (12%) and calcium phosphate (2%) occurred less frequently. Provided they are not causing obstruction, struvite nephroliths may be dissolved with medical protocols. Although there are no dissolution protocols for nephroliths containing calcium, risk-benefit ratios should be considered before proceeding with surgery.

Animals↗

PubMed1999

Drug-induced urolithiasis.

Diagnostic and therapeutic drugs may enhance urolithiasis in one or a combination of ways, including: (1) alteration of urine pH in such fashion as to create an environment that increases the solubility of some lithogenic substances, (2) alteration of glomerular filtration rate, tubular reabsorption, and tubular secretion of drugs of endogenous substances so as to enhance promoters or impair inhibitors of urolithiasis, and (3) precipitation (e.g., drugs or their metabolites) to form a portion or all of a urolith.

Allopurinol↗

PubMed1999

Canine retrograde urohydropropulsion. Lessons from 25 years of experience.

Uroliths are commonly voided into the urethra where they often lodge adjacent to the os penis in male dogs. Urethral patency can, with few exceptions, be restored by flushing uroliths back into the bladder lumen by retrograde urohydropropulsion. To be consistently successful, one must be familiar with the concepts of the procedure and each step of the technique.

Animals↗

PubMed1999

Voiding urohydropropulsion. Lessons from 5 years of experience.

Voiding urohydropropulsion is a nonsurgical method of removing uroliths from the urinary bladder. Any urocystolith of sufficient size to pass through the distended urethral lumen can be safely and effectively removed by this technique. Compared to cystotomy, voiding urohydropropulsion offers several advantages: urolith removal can be performed in minutes, anesthetic period is shorter, postprocedural dysuria and hematuria are less severe, and it provides greater success for complete removal of small urocystoliths. This technique is not suitable for removal of large urocystoliths or uroliths that become lodged in the urethral lumen.

Animals↗

PubMed1998

Evaluation of the morphologic characteristics and prevalence of canine urocystoliths from a regional urolith center.

OBJECTIVE: To determine whether morphology of single-mineral urocystoliths and age, sex, or breed data could be applied to facilitate radiographic and clinical urocystolith mineral type prediction, respectively, in dogs. SAMPLE POPULATION: Database of 2,041 dogs with pure mineral composition urocystoliths. PROCEDURE: All uroliths were characterized according to geologic descriptive terminology and by breed, sex, and age of dog at time of sample submission. Summary statistics were used to compare features with specific mineral types. Observed trends were analyzed for statistical relevance between observed and expected frequencies for age, sex, color, size, shape, and surface, using the null hypothesis that differences by urocystolith mineral type did not exist. On the basis of expected breed occurrence derived by equations, the null hypothesis that urocystolith occurrence paralleled canine breed popularity was tested. RESULTS: Urocystoliths > 10 mm in any dimension were > 92% likely to be magnesium ammonium phosphate hexahydrate (MAP). Smooth, blunt-edged or faceted, and pyramidal urocystoliths were usually MAP. Jackstone shapes were almost always silica. Botryoidal (grape-like clusters) urocystoliths were likely to be oxalates. Breeds with high relative likelihood of urocystoliths included: English Bulldog, Pekingese, Pug, Welsh Corgi, and West Highland White Terrier. Breeds with low relative likelihood of urocystolith production included: German Shepherd Dog, Shar-Pei, and German Shorthaired Pointer. About 94% of urocystoliths produced in females or spayed females were MAP, whereas males and neutered males produced a greater assortment. CONCLUSIONS AND CLINICAL RELEVANCE: For pure mineral composition urocystoliths, trends in mineral type among breeds and between sexes can be exploited clinically in the diagnosis and management of urolith-related disease. Size and shape, used in conjunction with age, breed, and sex, can facilitate pure urocystolith mineral type prediction.

Age Factors↗

PubMed1997

Effects of time and dilution on concentration of xanthine in frozen urine and plasma of dogs.

OBJECTIVE: To evaluate the effects of dilution on stability of xanthine in canine urine stored at -20 C, and to evaluate the effects of storage at -20 C on stability of xanthine in canine plasma. ANIMALS: 6 reproductively intact female Beagles, 3.9 to 4.2 years old and weighing 8.5 to 10.1 kg. PROCEDURE: Dogs were fed a 31.4% protein (dry weight), meat-based diet for 21 days, and administered allopurinol (15 mg/kg of body weight, q 12 h) during days 14 to 21; urine and plasma samples were obtained on day 22. Urine samples were preserved undiluted or diluted, and divided into 1-ml aliquots for storage at -20 C for 1 to 12 weeks. Plasma samples were divided into 1-ml aliquots for storage at -20 C for 1 to 12 weeks. Urine and plasma xanthine concentrations were measured on day of collection (baseline) and after 1, 2, 4, 6, 9, and 12 weeks. RESULTS: Dilution of urine samples did not have a significant effect on consistency of xanthine concentration measured for up to 12 weeks of storage. Although xanthine concentration did not differ significantly between undiluted and diluted urine samples, average xanthine concentration measured in diluted samples was consistently higher, compared with that in undiluted samples. Compared with baseline values, plasma xanthine concentration was significantly lower at 6, 9, and 12 weeks of storage. CONCLUSIONS: Measurement of xanthine concentration is reproducible in undiluted or diluted urine samples for up to 12 weeks, although dilution may provide better results. Measurement of plasma xanthine concentration is reproducible in samples stored for up to 4 weeks. CLINICAL RELEVANCE: To ensure reproducibility of measurements of xanthine concentration in urine samples collected from dogs that are affected with urate uroliths and receiving allopurinol, urine should be diluted 1:20 with deionized water. These measurements may be useful for monitoring dogs that are receiving allopurinol for dissolution or prevention of urate uroliths.

Animals↗

PubMed1997

Effects of sample handling on total carbon dioxide concentrations in canine and feline serum and blood.

OBJECTIVE: To determine whether underfilling blood collection tubes leads to in vitro reduction in serum measured total CO2 concentration ([TCO2]m) in canine and feline blood samples sufficient to create the impression of metabolic acidosis (pseudometabolic acidosis) or high anion gap. SAMPLE POPULATION: Blood samples from healthy client-owned animals (16 dogs, 17 cats). PROCEDURE: Venous blood samples were collected in random order for determination of serum [TCO2] and blood gas tensions. Blood gas analysis was performed on iced, capped blood samples. In dogs, serum [TCO2] was measured in 1-, 3-, and 10-ml samples in 10-ml type-B tubes and in a 3-ml sample in 3-ml type-A tubes. In cats, serum [TCO2] was determined in 1-, 2-, and 3-ml samples in 3-ml type-A tubes and in a 3-ml sample in 10-ml type-B tubes. RESULTS: For dogs, serum [TCO2] in full-tube, 10-ml samples was a mean +/- SD, 2.0 +/- 1.1 mmol/L greater than that in 3-ml samples and 3.7 +/- 1.3 mmol/L greater than the value in 1-ml samples; both differences were significant at P < 0.0001. The serum [TCO2] in full 3-ml samples was lower by 0.4 +/- 0.6 mmol/L than the value in full-tube 10-ml samples (P = 0.019). For cats, serum [TCO2] in full-tube, 3-ml samples was 0.5 +/- 0.6 mmol/L greater than that in 2-ml samples (P = 0.004) and was 1.5 +/- 0.8 mmol/L greater than the value in 1-ml samples (P < 0.0001). Serum [TCO2] in 3-ml samples of feline blood in 10-ml tubes was 0.8 +/- 0.8 mmol/L lower than that in samples from full 3-ml tubes (P = 0.0007). In dogs and cats, [TCO2] in fully filled collection tubes was approximately 6 mmol/L higher when calculated from blood gas analysis data than when chemically determined in serum. CONCLUSIONS AND CLINICAL RELEVANCE: Underfilling blood collection tubes results in a false decrease in serum [TCO2], which can contribute in part to descrepancies between blood gas and chemical analyses as estimates of plasma bicarbonate concentration. This, and other in vitro effects of sample handling and collection, may result in a false assessment of metabolic acidosis in dogs and cats.

Acidosis↗

PubMed1997

Bioavailability and pharmacokinetics of intravenously and orally administered allopurinol in healthy beagles.

OBJECTIVES: To determine bioavailability and pharmacokinetic parameters for allopurinol and its active metabolite, oxypurinol. ANIMALS: 6 healthy, reproductively intact female Beagles, 4.9 to 5.2 years old, and weighing 9.5 to 11.5 kg. PROCEDURE: In the first part of the study, allopurinol was administered IV at a dosage of 10 mg/kg of body weight to 3 dogs and 5 mg/kg to 3 dogs; the sequence was then reversed. In the second part of the study, allopurinol was administered orally at a dosage of 15 mg/kg to 3 dogs and 7.5 mg/kg to 3 dogs; the sequence was then reversed. In the third part of the study, allopurinol was administered IV (10 mg/kg), orally (15 mg/kg) with food, and orally (15 mg/kg) without food. Plasma samples were obtained at timed intervals, and concentrations of allopurinol and oxypurinol were determined. RESULTS: Maximal plasma allopurinol concentration and area under plasma allopurinol and oxypurinol concentration-time curves were 2 times greater when dogs were given 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs were given 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg. Allopurinol elimination half-life, time to reach maximal plasma oxypurinol concentration, and oxypurinol elimination half-life were significantly greater when dogs received 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs received 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg. CONCLUSIONS: Elimination of allopurinol is dependent on nonlinear enzyme kinetics. The bioavailability of allopurinol, and pharmacokinetic parameters of allopurinol and oxypurinol after oral administration of allopurinol, are not affected by administration with food. CLINICAL RELEVANCE: A dose threshold exists beyond which additional allopurinol would not substantially further inhibit xanthine oxidase activity. Oral administration of > 15 mg of allopurinol/kg to dogs would not be expected to result in greater reduction of plasma and urine uric acid concentrations. Also, allopurinol may be administered to dogs for dissolution or prevention of urate uroliths without regard to time of feeding.

Administration, Oral↗

PubMed1997

Influence of two diets on pharmacokinetic parameters of allopurinol and oxypurinol in healthy beagles.

OBJECTIVES: To determine whether diet influences the metabolism of IV administered allopurinol in healthy dogs. ANIMALS: 6 healthy female Beagles, 4.9 to 5.2 years old and weighing 9.6 to 11.5 kg. PROCEDURES: Allopurinol was administered IV (10 mg/kg) while dogs consumed a 10.4% protein (dry weight), casein-based diet or a 31.4% (dry weight), meat-based diet. After each dose, plasma samples were obtained at timed intervals, and concentrations of allopurinol and its active metabolite, oxypurinol, were determined by high-performance liquid chromatography. An iterative, nonlinear regression analytical program was used to determine the weighted least-squares, best-fit curves for plasma allopurinol and oxypurinol concentration-time data. From these data, pharmacokinetic parameters were calculated. RESULTS: Pharmacokinetic parameters for allopurinol and oxypurinol were not different when comparing the effect of diet. CONCLUSION: There is no influence of diet on pharmacokinetic parameters of allopurinol or oxypurinol. CLINICAL RELEVANCE: In contrast to observations in human beings, allopurinol metabolism is not influenced by diet. Therefore, formation of xanthine-containing calculi in dogs consuming a high-protein diet and receiving allopurinol is probably not attributable to alteration of allopurinol metabolism.

Allopurinol↗

PubMed1996

Epizootiologic evaluation of urolithiasis in cats: 3,498 cases (1982-1992).

OBJECTIVE: to test the hypothesis that breed, sex and age of cats, and anatomic location of uroliths are risk factors for calcium oxalate and magnesium ammonium phosphate urolithiasis. DESIGN: Retrospective case-control study. SAMPLE POPULATION: Records of 3,498 feline urolith accessions submitted between September 1982 and September 1992. PROCEDURE: Mineral composition of feline uroliths was quantitatively analyzed. Odds ratios and 95% confidence intervals were calculated for breed, sex, age, and urolith location as risk factors for calcium oxalate and magnesium ammonium phosphate urolith formation. The population at risk was defined as all cats for which that type of urolith had been submitted. The control population was all cats for which uroliths had been submitted, excluding cats with the type of urolith being evaluated. RESULTS: Burmese, Persian, and Himalayan breeds were at higher risk for developing calcium oxalate uroliths, but at reduced risk for developing magnesium ammonium phosphate uroliths. Compared with females, neutered male cats had a higher risk for developing calcium oxalate uroliths, but a reduced risk for developing magnesium ammonium phosphate uroliths. The risk for calcium oxalate urolith formation increased with age. One- to 2-year-old female cats had the highest risk for magnesium ammonium phosphate uroliths. Uroliths removed from the kidneys were more likely to be composed of calcium oxalate than of magnesium ammonium phosphate. CLINICAL IMPLICATIONS: Breed, sex, and age of cats, and anatomic location of uroliths should be considered when evaluating risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in urolith-forming cats.

Age Factors↗