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Abstract

Objective—To determine the pharmacokinetics of DL-α-lipoic acid in dogs when administered at 3 dosages via 3 methods of delivery.

Animals—27 clinically normal Beagles.

Procedures—In a 3 × 3 factorial Latin square design, 3 dosages (2.5, 12.5, and 25 mg/kg) of DL-α-lipoic acid were administered orally in a capsule form and provided without a meal, in a capsule form and provided with a meal, and as an ingredient included in an extruded dog food. Food was withheld for 12 hours prior to DL-α-lipoic acid administration. Blood samples were collected before (0 minutes) and at 15, 30, 45, 60, and 120 minutes after administration. Plasma concentrations of DL-α-lipoic acid were determined via high-performance liquid chromatography. A generalized linear models procedure was used to evaluate the effects of method of delivery and dosage. Noncompartmental analysis was used to determine pharmacokinetic parameters of DL-α-lipoic acid. Nonparametric tests were used to detect significant differences between pharmacokinetic parameters among treatment groups.

Results—A significant effect of dosage was observed regardless of delivery method. Method of delivery also significantly affected plasma concentrations of DL-α-lipoic acid, with extruded foods resulting in lowest concentration for each dosage administered. Maximum plasma concentration was significantly affected by method of delivery at each dosage administered. Other significant changes in pharmacokinetic parameters were variable and dependent on dosage and method of delivery.

Conclusions and Clinical Relevance—Values for pharmacokinetic parameters of orally administered DL-α-lipoic acid may differ significantly when there are changes in dosage, method of administration, and fed status.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the reliability of taurine concentrations measured in a single urine sample obtained from dogs 8 hours after eating, compared with taurine concentrations measured in 24-hour urine samples.

Animals

18 healthy Beagles.

Procedure

After emptying the urinary bladder by transurethral catheterization, dogs were fed a canned maintenance diet. Approximately 8 hours later, urine, plasma, and serum samples were obtained for determination of fractional urinary excretion of taurine and urine taurine-to-creatinine concentration ratios (Utaur:Ucr). Results were compared with 24-hour urinary taurine excretion rate.

Results

Unbound and total fractional urinary taurine excretion correlated well with unbound and total 24- hour urinary taurine excretion. However, bound fractional urinary taurine excretion correlated poorly with bound 24-hour urinary taurine excretion. Unbound and total Utaur:Ucr correlated well with unbound and total 24-hour urinary taurine excretion. However, bound Utaur:Ucr correlated poorly with bound 24-hour urinary taurine excretion.

Conclusion and Clinical Relevance

Fractional urinary excretion of unbound and total taurine, and unbound and total Utaur:Ucr are reliable indicators of 24-hour urinary unbound and total taurine excretion in healthy dogs. However, determination of 24-hour urinary taurine excretion is recommended for evaluating urinary bound taurine concentrations of dogs. (Am J Vet Res 1999;60:186–189)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate plasma taurine concentrations (PTC), whole blood taurine concentrations (WBTC), and echocardiographic findings in dogs fed 1 of 3 protein-restricted diets that varied in fat and L-carnitine content.

Animals—17 healthy Beagles.

Design—Baseline PTC and WBTC were determined, and echocardiography was performed in all dogs consuming a maintenance diet. Dogs were then fed 1 of 3 protein-restricted diets for 48 months: a low-fat (LF) diet, a high-fat and L-carnitine supplemented (HF + C) diet, or a high-fat (HF) diet. All diets contained methionine and cystine concentrations at or above recommended Association of American Feed Control Officials (AAFCO) minimum requirements. Echocardiographic findings, PTC, and WBTC were evaluated every 6 months.

Results—The PTC and WBTC were not significantly different among the 3 groups after 12 months. All groups had significant decreases in WBTC from baseline concentrations, and the HF group also had a significant decrease in PTC. One dog with PT and WBT deficiency developed dilated cardiomyopathy (DCM). Taurine supplementation resulted in significant improvement in cardiac function. Another dog with decreased WBTC developed changes compatible with early DCM.

Conclusion and Clinical Relevance—Results revealed that dogs fed protein-restricted diets can develop decreased taurine concentrations; therefore, protein-restricted diets should be supplemented with taurine. Dietary methionine and cystine concentrations at or above AAFCO recommended minimum requirements did not prevent decreased taurine concentrations. The possibility exists that AAFCO recommended minimum requirements are not adequate for dogs consuming protein-restricted diets. Our results also revealed that, similar to cats, dogs can develop DCM secondary to taurine deficiency, and taurine supplementation can result in substantial improvement in cardiac function. (Am J Vet Res 2001;62:1616–1623)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine an optimal window for determining peak flatulence and evaluate the effects of oligosaccharides and supplemental β-mannanase in soybean meal–based diets on nutrient availability and flatulence.

Animals—6 dogs.

Procedures—Dogs were used in a 2 × 3 factorial arrangement of treatments in a 6 × 6 Latin square experiment to evaluate the digestibility, flatulence, and fecal odor metabolites of low-oligosaccharide low-phytate soybean meal (LLM), conventional soybean meal (SBM), and poultry by-product (PBP) meal diets with or without supplemental β-mannanase (5 g/kg).

Results—Enzyme supplementation had no effect on total tract dry matter (DM), nitrogen digestibility, or digestible energy; however, differences between protein sources did exist for total tract DM digestibility and digestible energy. The PBP meal had higher DM digestibility and digestible energy (mean, 0.913 and 4,255 cal/g), compared with soy-based diets (mean, 0.870 and 4,049 cal/g). No differences were detected for any treatment regardless of protein source or addition of supplemental enzyme for any flatulence components analyzed. No differences were detected for all fecal odor metabolites regardless of addition of supplemental enzyme; however, differences between protein sources were detected. The PBP meal had lower concentrations of carboxylic acids and esters and higher concentrations of heterocycles, phenols, thio and sulfides, ketones, alcohols, and indoles than LLM and SBM.

Conclusions and Clinical Relevance—Diets containing < 22.4 g of stachyose/kg and < 2 g of raffinose/kg did not alter digestibility or increase flatulence in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of high- and lowprotein diets with or without tryptophan supplementation on behavior of dogs with dominance aggression, territorial aggression, and hyperactivity.

Design—Prospective crossover study.

Animals—11 dogs with dominance aggression, 11 dogs with territorial aggression, and 11 dogs with hyperactivity.

Procedure—In each group, 4 diets were fed for 1 week each in random order with a transition period of not < 3 days between each diet. Two diets had low protein content (approximately 18%), and 2 diets had high protein content (approximately 30%). Two of the diets (1 low-protein and 1 high-protein) were supplemented with tryptophan. Owners scored their dog's behavior daily by use of customized behavioral score sheets. Mean weekly values of 5 behavioral measures and serum concentrations of serotonin and tryptophan were determined at the end of each dietary period.

Results—For dominance aggression, behavioral scores were highest in dogs fed unsupplemented high-protein rations. Tryptophan-supplemented low-protein diets were associated with significantly lower behavioral scores than low-protein diets without tryptophan supplements.

Conclusions and Clinical Relevance—For dogs with dominance aggression, the addition of tryptophan to high-protein diets or change to a low-protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low-protein diet may be helpful in reducing aggression. (J Am Vet Med Assoc 2000;217:504–508)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate the reliability of urine carnitine concentrations measured in single postprandial samples, compared with carnitine concentrations measured in 24-hour urine samples.

Animals

19 healthy Beagles.

Procedure

After emptying the urinary bladder by catheterization, dogs were fed a canned canine maintenance diet. Approximately 8 hours later, urine, plasma, and serum samples were obtained for determination of urinary carnitine fractional excretion and urine carnitine-to-creatinine concentration ratio. Results were compared with 24-hour urinary carnitine excretion rate.

Results

Fractional excretion of carnitine and urine carnitine-to-creatinine ratios correlated poorly with 24-hour urinary carnitine excretion.

Conclusion

Determination of 24-hour urinary carnitine excretion is recommended to measure urine carnitine concentrations in dogs. (Am J Vet Res 1996;57: 1185-1188)

Free access
in American Journal of Veterinary Research

SUMMARY

Objective

To determine how long serum concentrations of ω-3 fatty acids remain elevated after cessation of dietary fish oil supplementation.

Animals

12 healthy Beagles.

Procedure

Baseline serum concentrations of linoleic acid, linolenic acid, arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were measured. Dogs were then fed a diet supplemented with soybean oil or fish oil for 8 weeks, and serum fatty acid concentrations were measured while dogs were fed the experimental diets and for 18 weeks after they were switched to a maintenance diet.

Results

For dogs fed the fish oil diet, serum EPA and DHA concentrations were significantly increased by week 1 and remained increased for 7 (DHA concentration) or 3 (EPA concentration) weeks after dietary fish oil supplementation was discontinued.

Conclusions

In dogs, supplementation of the diet with fish oil may have effects for several weeks after dietary supplementation is discontinued.

Clinical Relevance

Studies of the effects of fish oil supplementation that use a crossover design should allow for an appropriate washout period. (Am J Vet Res 1998;59:864–868)

Free access
in American Journal of Veterinary Research