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Abstract

Objective—To compare indicators of postoperative pain and behavior in dogs with and without a lowdose ketamine infusion added to usual perioperative management.

Design—Prospective, randomized, blinded clinical study.

Animals—27 dogs undergoing forelimb amputation.

Procedure—Dogs were anesthetized with glycopyrrolate, morphine, propofol, and isoflurane. Thirteen dogs were treated with ketamine IV, as follows: 0.5 mg/kg (0.23 mg/lb) as a bolus before surgery, 10 µg/kg/min (4.5 µg/lb/min) during surgery, and 2 µg/kg/min (0.9 µg/lb/min) for 18 hours after surgery. Fourteen dogs received the same volume of saline (0.9% NaCl) solution. All dogs received an infusion of fentanyl (1 to 5 µg/kg/h [0.45 to 2.27 µg/lb/h]) for the first 18 hours after surgery. Dogs were evaluated for signs of pain before surgery, at the time of extubation, and 1, 2, 3, 4, 12, and 18 hours after extubation. Owners evaluated their dogs' appetite, activity, and wound soreness on postoperative days 2, 3, and 4.

Results—Dogs that received ketamine infusions had significantly lower pain scores 12 and 18 hours after surgery and were significantly more active on postoperative day 3 than dogs that received saline solution infusions.

Conclusions and Clinical Relevance—Results suggest that perioperative administration of low doses of ketamine to dogs may augment analgesia and comfort in the postoperative surgical period. (J Am Vet Med Assoc 2002;221:72–75)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate changes in resting energy expenditure (REE) as well as protein and carbohydrate metabolism in dogs with osteosarcoma (OSA).

Animals—15 weight-stable dogs with OSA that did not have other concurrent metabolic or endocrine illness and twelve 1-year-old sexually intact female Beagles (control dogs).

Procedures—Indirect calorimetry was performed on all dogs to determine REE and respiratory quotient (RQ). Stable isotope tracers (15N-glycine, 4.5 mg/kg of body weight, IV; 6,6-deuterium-glucose, 4.5 mg/kg, IV as a bolus, followed by continuous-rate infusion at 1.5 mg/kg/h for 3 hours) were used to determine rate of protein synthesis and glucose flux in all dogs. Dualenergy x-ray absorptiometry (DEXA) scans were performed to determine total body composition.

Results—Accounting for metabolic body size, REE in dogs with OSA was significantly higher before and after surgery, compared with REE of healthy control dogs. The RQ values did not differ significantly between groups. Dogs with OSA also had decreased rates of protein synthesis, increased urinary nitrogen loss, and increased glucose flux during the postoperative period.

Conclusions and Clinical Relevance—Alterations in energy expenditure, protein synthesis, urinary nitrogen loss, and carbohydrate flux were evident in dogs with OSA, similar to results documented in humans with neoplasia. Changes were documented in REE as well as protein and carbohydrate metabolism in dogs with OSA. These changes were evident even in dogs that did not have clinical signs of cachexia. (Am J Vet Res 2001;62:1234–1239)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of various diets on the pharmacokinetics of phenobarbital and the interactive effects of changes in body composition and metabolic rate.

Design—Prospective study.

Animals—27 healthy sexually intact adult female Beagles.

Procedure—Pharmacokinetic studies of phenobarbital were performed before and 2 months after dogs were fed 1 of 3 diets (group 1, maintenance diet; group 2, protein-restricted diet; group 3, fat- and protein-restricted diet) and treated with phenobarbital (approx 3 mg/kg [1.4 mg/lb] of body weight, PO, q 12 h). Pharmacokinetic studies involved administering phenobarbital (15 mg/kg [6.8 mg/lb], IV) and collecting blood samples at specific intervals for 240 hours. Effects of diet and time were determined by repeated-measures ANOVA.

Results—Volume of distribution, mean residence time, and half-life (t1/2) of phenobarbital significantly decreased, whereas clearance rate and elimination rate significantly increased with time in all groups. Dietary protein or fat restriction induced significantly greater changes: t1/2 (hours) was lower in groups 2 (mean ± SD; 25.9 ± 6.10 hours) and 3 (24.0 ± 4.70) than in group 1 (32.9 ± 5.20). Phenobarbital clearance rate (ml/kg/min) was significantly higher in group 3 (0.22 ± 0.05 ml/kg/min) than in groups 1 (0.17 ± 0.03) or 2 (0.18 ± 0.03). Induction of serum alkaline phosphatase activity (U/L) was greater in groups 2 (192.4 ± 47.5 U/L) and 3 (202.0 ± 98.2) than in group 1 (125.0 ± 47.5).

Conclusions and Clinical Relevance—Clinically important differences between diet groups were observed regarding pharmacokinetics of phenobarbital, changes in CBC and serum biochemical variables, and body composition. Drug dosage must be reevaluated if a dog's diet, body weight, or body composition changes during treatment. Changes in blood variables that may indicate liver toxicosis caused by phenobarbital may be amplified by diet-drug interactions. (J Am Vet Med Assoc 2000;217:847–852)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine effects of dietary cysteine on blood sulfur amino acids (SAA), reduced glutathione (GSH), oxidized glutathione (GSSG), and malondialdehyde (MDA) concentrations in cats.

Animals

12 healthy adult cats.

Procedure

Cats were fed diets with a nominal (0.50 g/100 g dry matter [DM]), moderate (1.00 g/100 g DM), or high (1.50 g/100 g DM) cysteine content in a 3 × 3 Latin square design with blocks of 8 weeks’ duration. Venous blood samples were collected after each diet had been fed for 4 and 8 weeks, and a CBC and serum biochemical analyses were performed; poikilocyte, reticulocyte, and Heinz body counts were determined; and MDA, GSH, GSSG, and SAA concentrations were measured.

Results

Blood cysteine and MDA concentrations were not significantly affected by dietary cysteine content. Blood methionine, homocysteine, and GSSG concentrations were significantly increased when cats consumed the high cysteine content diet but not when they consumed the moderate cysteine content diet, compared with concentrations obtained when cats consumed the nominal cysteine content diet. Blood GSH concentrations were significantly increased when cats consumed the moderate or high cysteine content diet.

Conclusions

Increased dietary cysteine content promotes higher blood methionine, homocysteine, GSH, and GSSG concentrations in healthy cats.

Clinical Relevance

Supplemental dietary cysteine may be indicated to promote glutathione synthesis and ameliorate adverse effects of oxidative damage induced by disease or drugs. (Am J Vet Res 1999;60:328–333)

Free access
in American Journal of Veterinary Research

Objective

To determine the effectiveness and safety of asparaginase administered SC versus IM for treatment of multicentric lymphoma in dogs receiving doxorubicin.

Design

Prospective study.

Animals

49 dogs with multicentric lymphoma

Procedure

Dogs were treated with doxorubicin every 3 weeks, for a total of 5 treatments, and were given 3 weekly treatments of asparaginase, SC or IM. Using high-performance liquid chromatography, mean plasma asparagine, aspartic acid, glutamine, and glutamic acid concentrations were determined in dogs before and during treatment with asparaginase (10,000 U/m2 of body surface area, once a week for 3 weeks). Asparaginase was administered SC in 23 dogs and IM in 26 dogs. Variables evaluated included time to response to chemotherapy, remission and survival times, and clinical and serum biochemical indicators of toxicoses

Results

Using the World Health Organization's staging system for lymphoma, 30 dogs were in clinical stage III and 19 were in clinical stage IV. One week after asparaginase treatment, plasma asparagine concentrations were low and plasma aspartic acid, glutamine, and glutamic acid concentrations were high. Differences in plasma amino acid concentrations were not found between SC and IM groups. For dogs in clinical stage IV, IM administration of asparaginase significantly decreased the number of days to complete remission, compared with SC administration (8 vs 17 days, respectively). For dogs in clinical stage III, IM administration favorably increased the duration of first remission (191 vs 103 days) and survival time (289 vs 209 days). Overall, dogs treated IM had a faster response to chemotherapy (9 vs 15 days), a longer remission (191 vs 109 days), and a longer survival time (286 vs 198 days), compared with all dogs treated SC. Asparaginase toxicoses were not observed regardless of the route of administration.

Clinical Implications

For dogs with multicentric lymphoma that are receiving doxorubicin, IM treatment with asparaginase is more effective than SC treatment. (J Am Vet Med Assoc 1999;214:353–356)

Free access
in Journal of the American Veterinary Medical Association

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

Abstract

Objective—To determine the effect of dietary n-3 fatty acids on the pharmacokinetics of doxorubicin in dogs with lymphoma.

Animals—23 dogs with lymphoma in stages IIIa, IVa, and Va.

Procedure—Dogs receiving doxorubicin chemotherapy were randomly allocated to receive food with a high (test group) or low (control group) content of n-3 fatty acids. Serum doxorubicin and doxorubicinol concentrations were measured via high-performance liquid chromatography before and 6 to 9 weeks after initiation of the diets. Lymph node concentrations of doxorubicin were assessed 6 hours after the initial treatment. Dogs' body composition was assessed by means of dual-energy x-ray absorptiometry scans.

Results—No significant differences in doxorubicin pharmacokinetics were detected between treatment groups. Significant differences existed between the first and second sampling times among all dogs for area under the curve, maximum serum concentration, and clearance. Differences in body composition did not affect measured pharmacokinetic variables. The terminal elimination half-life was longer in dogs in which a long-term remission was achieved than in dogs that did not have remission.

Conclusions and Clinical Relevance—Dietary supplementation of n-3 fatty acids is common in veterinary patients with neoplasia, but supplementation did not affect doxorubicin pharmacokinetics in this population of dogs. Explanations for the beneficial effects of n-3 fatty acids other than alterations in the pharmacokinetics of chemotherapy drugs should be investigated. Dogs may metabolize drugs differently prior to remission of lymphoma than when in remission. The pharmacokinetics of doxorubicin at the time of the first administration may predict response to treatment.

Full access
in American Journal of Veterinary Research