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  • Author or Editor: Peter J. Markwell x
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Abstract

Objective—To compare urine composition in Labrador Retrievers (LR) and Miniature Schnauzers (MS) fed the same dog food.

Animals—8 healthy LR (mean [± SD] age, 3.1 ± 1.7 years) and 8 healthy MS (mean age, 3.7 ± 1.3 years).

Procedure—A nutritionally complete dry dog food was fed to the dogs for 24 days. Urinary pH, volume, specific gravity, frequency of urination, and urinary concentrations of 12 analytes were measured for each dog; urinary relative supersaturation (RSS) with calcium oxalate and brushite (calcium hydrogen phosphate dihydrate) were calculated from these values.

Results—MS urinated significantly less often and had a lower urine volume (ml/kg of body weight per d) and a significantly higher urine pH, compared with LR. Urinary calcium concentration and brushite RSS were significantly higher in the urine of MS. As a result of a high calorie requirement, primarily as a result of high surface area to volume ratio, MS had significantly higher intake (per kg body weight) of dietary minerals, compared with LR.

Conclusions and Clinical Relevance—Differences in urine composition exist between breeds fed the same diet, some of which, including lower urine volume, higher calcium concentration, and higher brushite RSS, may contribute to the high prevalence of calcium oxalate uroliths observed in MS. Differences between breeds should be considered when evaluating strategies for controlling calcium oxalate stone formation. (Am J Vet Res 2001;62:1782–1786)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate 3 commercially available selected-protein-source diets as maintenance diets in dogs with pruritus caused by adverse food reactions.

Design—Randomized crossover trial.

Animals—40 dogs > 6 months of age with pruritus caused by adverse reactions to foods.

Procedure—Diagnosis was confirmed by use of diet elimination and provocation studies. Subsequently, dogs were fed 3 commercial diets for 3 weeks each in a randomized, blinded, crossover trial. Dogs were evaluated for pruritus, vomiting, diarrhea, and flatulence.

Results—Pruritus recurred in 52.5% of dogs fed a chicken-rice diet, 47.5% of dogs fed a catfish-rice diet, and 85% of dogs fed a venison-rice diet. Overall, 95% of the dogs could be managed successfully with at least 1 of the 3 diets.

Conclusions and Clinical Relevance—Results indicated that commercially available limited-allergen diets with selected protein sources may be appropriate for long-term management of pruritus caused by adverse food reactions. Testing of various protein sources is usually required. (J Am Vet Med Assoc 2001;219:1411–1414)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine prevalence of systolic hypertension and associated risk factors in cats with chronic renal failure evaluated in first-opinion practice.

Design—Prospective study.

Animals—103 cats with chronic renal failure.

Procedure—Systolic arterial blood pressure (SABP) was measured with a noninvasive Doppler technique, and cats that had SABP > 175 mm Hg on 2 occasions or that had SABP > 175 mm Hg and compatible ocular lesions were classified as hypertensive. Information from the history (previous treatment for hyperthyroidism, age), physical examination (sex, body weight), routine plasma biochemical analyses (creatinine, cholesterol, potassium, sodium, chloride, and calcium concentrations), and thyroid status were evaluated as potential risk factors for systolic hypertension. Variables associated with systolic hypertension were evaluated by use of logistic regression.

Results—20 (19.4%; 95% confidence interval, 13 to 28%) cats had systolic hypertension. Plasma potassium concentration was significantly and inversely associated with systolic hypertension.

Conclusions and Clinical Relevance—Prevalence of systolic hypertension, although clinically important, was lower than that reported previously. The cause of the inverse association between systolic hypertension and plasma potassium concentration is not yet known. (J Am Vet Med Assoc 2002;220:1799–1804)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To assess the effect of dietary potassium citrate supplementation on the urinary pH, relative supersaturation of calcium oxalate and struvite (defined as the activity product/solubility product of the substance), and concentrations of magnesium, ammonium, phosphate, citrate, calcium, and oxalate in dogs.

Animals—12 healthy adult dogs.

Procedure—Canned dog food was fed to dogs for 37 days. Dogs were randomly allocated to 3 groups and fed test diets for a period of 8 days. Study periods were separated by 6-day intervals. During each study period the dogs were fed either standard diet solus (control) or standard diet plus 1 of 2 types of potassium citrate supplements (150 mg potassium citrate/kg of body weight/d) twice daily. Urinary pH, volume and specific gravity, relative supersaturation of calcium oxalate and struvite, and concentrations of magnesium, ammonium, phosphate, calcium, oxalate, and citrate were assessed for each treatment.

Results—Mean urine pH was not significantly affected by dietary potassium citrate supplementation, although urine pH did increase by 0.2 pH units with supplementation. Diets containing potassium citrate maintained a higher urine pH for a longer part of the day than control diet. Three Miniature Schnauzers had a significantly lower urinary relative calcium oxalate supersaturation when fed a diet supplemented with potassium citrate, compared with control diet.

Conclusions and Clinical Relevance—Dietary potassium citrate supplementation has limited effects on urinary variables in most healthy dogs, although supplementation results in maintenance of a higher urine pH later in the day. Consequently, if supplementation is introduced, dogs should be fed twice daily and potassium citrate should be given with both meals or with the evening meal only. (Am J Vet Res 2000;61:430–435)

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in American Journal of Veterinary Research

Abstract

Objective—To determine effects of age and sex on plasma lipid and lipoprotein metabolism in cats.

Animals—33 kittens and 16 adolescent, 23 adult, and 10 senior cats.

Procedure—Plasma concentrations of cholesterol, triglyceride, and lipoprotein-cholesterol and activities of lipoprotein lipase, hepatic lipase, and lecithin:cholesterol acyl transferase (LCAT) were measured and compared within and among groups.

Results—Plasma cholesterol and triglyceride concentrations were significantly higher in 5- and 7-week-old kittens, compared with the same kittens after weaning and cats in the other age groups. Cholesterol concentration was significantly less in 20-week-old kittens, compared with adolescent and adult cats. Lipid and lipoprotein-cholesterol concentrations were not significantly different among the adolescent, adult, and senior groups, nor did sex influence lipid and lipoprotein-cholesterol concentrations in these groups. Activities of lipoprotein and hepatic lipases were significantly less in senior cats, compared with the other groups. Activity of LCAT was highest in 20-week-old kittens and was greater in sexually intact adult and adolescent females, compared with their male counterparts. After castration, activities of hepatic lipase and LCAT significantly decreased in adolescent male cats.

Conclusions and Clinical Relevance—The upper limits of reference ranges for plasma cholesterol and triglyceride concentrations should be increased for kittens < 8 weeks of age. Low cholesterol concentrations in adolescent cats likely reflect high tissue demands for growth and steroidogenesis. Decrease in lipoprotein and hepatic lipase activity in senior cats could predispose this age group to hypertriglyceridemia, particularly in insulin-resistant cats or those fed a high fat diet. (Am J Vet Res 2001;62:331–336)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the dietary patterns and intake of nutrients of concern in dogs with cardiac disease.

Design—Prospective study.

Animals—82 dogs with dilated cardiomyopathy (DCM) or chronic valvular disease.

Procedure—Owners of dogs were contacted and given a standardized telephone questionnaire regarding diet and a 24-hour food recall to determine daily intake of calories, protein, fat, sodium, potassium, and magnesium.

Results—Among the 82 dogs, 71% had no congestive heart failure (CHF), and 29% had CHF or a history of CHF. Sixty-one percent of dogs had concurrent diseases. Anorexia was or had been evident in 34% of dogs and was significantly more common in the CHF group and in dogs with DCM. Most dogs (92%) received some treats and table food, with a median percentage of daily calories from treats of 19% (range, 0% to 100%). Most owners (57%) that administered pills used human or pet foods for pill administration. Most dogs ate more than the Association of American Feed Control Officials (AAFCO) minimum values for fat and protein. Daily sodium intake varied from 14 to 384 mg/100 kcal, compared with the AAFCO minimum of 17 mg/100 kcal. A median of 25% of total daily sodium came from treats and table food (range, 0% to 100%). Dogs with CHF ate significantly more sodium, compared with dogs with no CHF.

Conclusions and Clinical Relevance—Dietary intake for dogs with cardiac disease is highly variable and often not optimal. (J Am Vet Med Assoc 2003;223: 1301–1305)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To develop a standardized meal challenge test by assessing associations between food-withheld preprandial (ie, fasting) and postprandial triglyceride concentrations, determining the most appropriate sampling time to detect the peak concentration (highest postprandial concentration), and estimating reference intervals for fasting and postprandial concentrations in healthy dogs.

Animals—12 lean healthy mixed-breed dogs.

Procedures—Dogs were fed a dry commercially available diet (fat, 31% metabolizable energy) for 3 weeks. After food was withheld for 23 to 24 hours, plasma triglyceride concentrations were measured 1 and 0.083 hours before and 1, 2, 3, 4, 5, 6, 9, and 12 hours after feeding of a standardized challenge meal (median amount eaten, 63 kcal/kg [127 kcal/kg0.75]). Correlation and agreement between concentrations at peak and other time points were assessed by use of correlation coefficients and Bland-Altman limits of agreement. Reference intervals were calculated by use of a robust method.

Results—Fasting and peak triglyceride concentrations were not closely associated. The highest concentration among samples obtained 2, 5, and 6 hours after meal consumption had closest agreement with peak concentration. In 5 of 12 dogs, concentrations 12 hours after eating were still significantly above baseline concentration (mean of each dog's fasting concentrations).

Conclusions and Clinical Relevance—Fasting triglyceride concentration could not be used to accurately predict peak concentration. When estimating peak concentration, multiple samples should be collected 2, 5, and 6 hours after consumption of a standardized meal. Food may need to be withheld for > 12 hours when assessing fasting concentrations in healthy dogs.

Full access
in American Journal of Veterinary Research