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To compare the effects of short-term dietary supplementation with vitamin D3 and 25-hydroxyvitamin D3 (25[OH]D3) on indicators of vitamin D status in healthy dogs.


13 purpose-bred adult dogs.


20 extruded commercial dog foods were assayed for 25(OH)D3 content. Six dogs received a custom diet containing low vitamin D concentrations and consumed a treat with vitamin D2 (0.33 μg/kg0.75) plus 1 of 3 doses of 25(OH)D3 (0, 0.23, or 0.46 μg/kg0.75) once daily for 8 weeks followed by the alternate treatments in a crossover-design trial. In another crossover-design trial, 7 dogs received a custom diet supplemented with vitamin D3 or 25(OH)D3 (targeted content, 3,250 U/kg [equivalent to 81.3 μg/kg] and 16 μg/kg, respectively, as fed) for 10 weeks followed by the alternate treatment. In washout periods before each trial and between dietary treatments in the second trial, dogs received the trial diet without D-vitamer supplements. Dietary intake was monitored. Serum or plasma concentrations of vitamin D metabolites and biochemical variables were analyzed at predetermined times.


25(OH)D3 concentrations were low or undetected in evaluated commercial diets. In the first trial, vitamin D2 intake resulted in quantifiable circulating concentrations of 25-hydroxyvitamin D2 but not 24R,25-dihydroxyvitamin D2. Circulating 25(OH)D3 concentration appeared to increase linearly with 25(OH)D3 dose. In the second trial, circulating 25(OH)D3 concentration increased with both D vitamer–supplemented diets and did not differ significantly between treatments. No evidence of vitamin D excess was detected in either trial.


Potency of the dietary 25(OH)D3 supplement estimated on the basis of targeted content was 5 times that of vitamin D3 to increase indicators of vita-min D status in the study sample. No adverse effects attributed to treatment were observed in short-term feeding trials. (Am J Vet Res 2021;82:722–736)

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in American Journal of Veterinary Research


Objective—To compare presumed fatty acid content in natural diets of feral domestic cats (inferred from body fat polyunsatrated fatty acids content) with polyunsaturated fatty acid content of commercial feline extruded diets.

Sample—Subcutaneous and intra-abdominal adipose tissue samples (approx 1 g) from previously frozen cadavers of 7 adult feral domestic cats trapped in habitats remote from human activity and triplicate samples (200 g each) of 7 commercial extruded diets representing 68% of market share obtained from retail stores.

Procedures—Lipid, triacylglycerol, and phospholipid fractions in adipose tissue samples and ether extracts of diet samples were determined by gas chromatography of methyl esters. Triacylglycerol and phospholipid fractions in the adipose tissue were isolated by thin-layer chromatography. Diet samples were also analyzed for proximate contents.

Results—For the adipose tissue samples, with few exceptions, fatty acids fractions varied only moderately with lipid fraction and site from which tissue samples were obtained. Linoleic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic acid fractions were 15.0% to 28.2%, 4.5% to 18.7%, 0.9% to 5.0%, < 0.1% to 0.2%, and 0.6% to 1.7%, respectively. As inferred from the adipose findings, dietary fractions of docosahexaenoic and α-linolenic acid were significantly greater than those in the commercial feline diets, but those for linoleic and eicosapentaenoic acids were not significantly different.

Conclusions and Clinical Relevance—The fatty acid content of commercial extruded feline diets differed from the inferred content of natural feral cat diets, in which dietary n-3 and possibly n-6 polyunsaturated fatty acids were more abundant. The impact of this difference on the health of pet cats is not known.

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in American Journal of Veterinary Research


Objective—To validate a recently developed commercially available leptin radioimmunoassay (RIA) for use with feline serum and evaluate the relationship between serum leptin concentrations and body fat mass in domestic cats.

Animals—19 sexually intact male specific–pathogenfree domestic cats that weighed 3.8 to 7.1 kg and were 1.1 to 3.5 years old.

Procedure—Specificity for feline leptin was evaluated by use of gel filtration chromatography and reversephase high-performance liquid chromatography fractionation of serum. Body fat mass was determined by use of the deuterium oxide (D2O) dilution method. Serum water D2O enrichment was measured by use of gas-phase Fourier transform infrared spectroscopy.

Results—Body fat mass and percentage body fat ranged from 0.3 to 2.3 kg and 7.5 to 34.9%, respectively. Serum leptin concentrations were lower in the unfed versus the fed state and ranged between 1.6 and 4.9 ng/ml human equivalent (HE); mean ± SD value was 2.9 ± 0.2 ng/ml HE. Leptin concentrations increased with increasing body fat mass and percentage of body fat.

Conclusions—Leptin is in the serum of domestic cats in free (> 78%) and apparently bound forms. The relationship between body fat and serum leptin concentration was similar to that observed in humans and rodents and indicative of a lipostatic role for leptin in cats. Cats that have an overabundance of body fat appear to be less sensitive to the weight-normalizing action of leptin than cats of ideal body condition. (Am J Vet Res 2000;61:796–801)

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in American Journal of Veterinary Research


Objective—To determine signalment, history, clinical signs, blood and plasma taurine concentrations, electrocardiographic and echocardiographic findings, treatment, and outcome of dogs with low blood or plasma taurine concentrations and dilated cardiomyopathy (DCM).

Design—Retrospective study.

Animals—12 client-owned dogs with low blood or plasma taurine concentrations and DCM.

Procedure—Medical records were reviewed, and clinical data were obtained.

Results—All 12 dogs were being fed a commercial dry diet containing lamb meal, rice, or both as primary ingredients. Cardiac function and plasma taurine concentration improved with treatment and taurine supplementation. Seven of the 12 dogs that were still alive at the time of the study were receiving no cardiac medications except taurine.

Conclusions and Clinical Relevance—Results suggest that consumption of certain commercial diets may be associated with low blood or plasma taurine concentrations and DCM in dogs. Taurine supplementation may result in prolonged survival times in these dogs, which is not typical for dogs with DCM. Samples should be submitted for measurement of blood and plasma taurine concentrations in dogs with DCM, and taurine supplementation is recommended while results of these analyses are pending. (J Am Vet Med Assoc 2003;223:1137–1141)

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in Journal of the American Veterinary Medical Association


Objective—To determine whether lipid particle coalescence develops in veterinary parenteral nutrition (PN) admixture preparations that are kept at room temperature (23°C) for > 48 hours and whether that coalescence is prevented by admixture filtration, refrigeration, or agitation.

Sample Population—15 bags of veterinary PN solutions.

Procedures—Bags of a PN admixture preparation containing a lipid emulsion were suspended and maintained under different experimental conditions (3 bags/group) for 96 hours while admixtures were dispensed to simulate IV fluid administration (rate, 16 mL/h). Bags were kept static at 4°C (refrigeration); kept at 23°C (room temperature) and continuously agitated; kept at room temperature and agitated for 5 minutes every 4 hours; kept static at room temperature and filtered during delivery; or kept static at room temperature (control conditions). Admixture samples were collected at 0, 24, 48, 72, and 96 hours and examined via transmission electron microscopy to determine lipid particle diameters. At 96 hours, 2 samples were collected at a location distal to the filter from each bag in that group for bacterial culture.

Results—Distribution of lipid particle size in the control preparations and experimentally treated preparations did not differ significantly. A visible oil layer developed in continuously agitated preparations by 72 hours. Bacterial cultures of filtered samples yielded no growth.

Conclusions and Clinical Relevance—Data indicated that the veterinary PN admixtures kept static at 23°C are suitable for use for at least 48 hours. Manipulations of PN admixtures appear unnecessary to prolong lipid particle stability, and continuous agitation may hasten lipid breakdown.

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in American Journal of Veterinary Research


Objective—To determine taurine status in a large group of Newfoundlands related by environment, diet, or breeding to a dog with dilated cardiomyopathy and taurine deficiency.

Design—Prospective study.

Animals—19 privately owned Newfoundlands between 5 months and 11.5 years old that had been fed commercial dry diets meeting established nutrient recommendations.

Procedure—Diet histories were obtained, and blood, plasma, and urine taurine concentrations and plasma methionine and cysteine concentrations were measured. In 8 dogs, taurine concentrations were measured before and after supplementation with methionine for 30 days. Ophthalmic examinations were performed in 16 dogs; echocardiography was performed in 6 dogs that were taurine deficient.

Results—Plasma taurine concentrations ranged from 3 to 228 nmol/mL. Twelve dogs had concentrations < 40 nmol/mL and were considered taurine deficient. For dogs with plasma concentrations < 40 nmol/mL, there was a significant linear correlation between plasma and blood taurine concentrations. For dogs with plasma concentrations > 40 nmol/mL, blood taurine concentrations did not vary substantially. Taurine-deficient dogs had been fed lamb meal and rice diets. Retinal degeneration, dilated cardiomyopathy, and cystinuria were not found in any dog examined for these conditions. The taurine deficiency was reversed by a change in diet or methionine supplementation.

Conclusions and Clinical Relevance—Results indicate a high prevalence of taurine deficiency among an environmentally and genetically related cohort of Newfoundlands fed apparently complete and balanced diets. Blood taurine concentrations indicative of taurine deficiency in Newfoundlands may be substantially less than concentrations indicative of a deficiency in cats. (J Am Vet Med Assoc 2003;223:1130–1136)

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in Journal of the American Veterinary Medical Association


Objective—To assess effects of deficiency of lipoprotein lipase (LPL) on body condition scores and lean and fat body masses of adult cats.

Animals—12 cats without LPL mutations and 23 cats that were heterozygous or homozygous carriers of the Gly412Arg LPL mutation.

Procedure—Lean and fat body masses were estimated by use of body condition scores and change in enrichment of serum after IV administration of deuterium oxide. Mass spectroscopy and infrared absorbance methods were used to determine deuterium enrichment.

Results—Fat body mass (mean ± SD; 0.2 ± 0.1 kg) and percentage body fat (6.2 ± 1.4%) of homozygotes were significantly less than those of clinically normal cats and heterozygotes (0.7 ± 0.1 kg, 18.2 ± 1.6% and 0.5 ± 0.1 kg, 15.6 ± 1.7%, respectively). Homozygous offspring of homozygous dams had significantly less fat body mass (0.1 ± 0.1 kg) and percentage body fat (2.1 ± 1.0%) than homozygous offspring of heterozygous dams (0.3 ± 0.1 kg and 9.2 ± 1.7%, respectively). Lean body mass did not differ significantly among groups. For all groups, percentage body fat was significantly correlated with body condition score (r = 0.65), and body condition scores supported findings for fat body mass.

Conclusions and Clinical Relevance—Deficiency of LPL activity in cats diminishes stores of body fat. This is consistent with a low rate of de novo synthesis of fat. The effect of dam on body masses in mature LPLdeficient cats indicates nutrient programming of adipose formation during gestation or lactation. (Am J Vet Res 2001;62:264–269)

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in American Journal of Veterinary Research