Fish oil decreases matrix metalloproteinases in knee synovia of dogs with inflammatory joint disease.

This study was designed to determine whether dietary fish oil affects the expression and activity of matrix metalloproteinases (MMP), tissue inhibitors of MMP-2 (TIMP-2) and urokinase plasminogen activator (uPA) in synovial fluid from dogs with spontaneously occurring stifle (knee) instability in a single hind limb resulting from acute cranial cruciate ligament (CCL) injury. Two groups of 12 dogs were fed diets from 1 week prior to surgery on the affected knee to 56 days post-surgery. The fish oil and control diets provided 90 and 4.5 mg, respectively, of combined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)/kg body weight per day. Plasma and synovial fluid, from both surgical and nonsurgical knee joints, were obtained at start of the diet (-7), surgery day (0) and 7, 14, 28 and 56 days post-surgery. Plasma total EPA and DHA were significantly increased, and plasma total arachidonic acid (AA) was significantly decreased by the fish oil diet. In synovial fluid from the nonsurgical knee, fish oil treatment significantly decreased proMMP-2 expression at Days 7 and 14, and proMMP-9 expression at Day 56, and uPA activity at 28 days and significantly increased TIMP-2 expression at Days 7 and 28. There were no differences in MMP expression or activity, TIMP-2 expression and uPA activity in the surgical joint synovial fluid at any time throughout the study. These results suggest that dietary fish oil may exert beneficial effects on synovial fluid MMP and TIMP-2 equilibrium in the uninjured stifle of dogs with unilateral CCL injury.

Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus.

This study compared the effects of a moderate carbohydrate-high fiber (MC-HF) food and a low carbohydrate-low fiber (LC-LF) food on glycemic control in cats with diabetes mellitus. Sixty-three diabetic cats (48 male castrated, 15 female spayed) were randomly assigned to be fed either a canned MC-HF (n = 32) food or a canned LC-LF (n = 31) food for 16 weeks. Owners were blinded to the type of diet fed. CBC, urinalysis, serum chemistry panel, fructosamine concentration and thyroxine concentration were determined on initial examination, and a complete blood count, serum chemistry panel, urinalysis and serum fructosamine concentration were repeated every 4 weeks for 16 weeks. Insulin doses were adjusted as needed to resolve clinical signs and lower serum fructosamine concentrations. Serum glucose (P = 0.0001) and fructosamine (P = 0.0001) concentrations significantly decreased from week 0 to week 16 in both dietary groups. By week 16, significantly more of the cats fed the LC-LF food (68%, 22/31), compared to the cats fed the MC-HF food (41%, 13/32), had reverted to a non-insulin-dependent state (P = 0.03). Cats in both groups were successfully taken off of insulin regardless of age, sex, type of insulin administered or duration of clinical disease before entering the study. There was no significant difference in the initial or final mean body weights or in the mean change in body weight from week 0 to week 16 between dietary groups. Diabetic cats in this study were significantly more likely to revert to a non-insulin-dependent state when fed the canned LC-LF food versus the MC-HF food.

Evaluation of the effects of dietary n-3 fatty acid supplementation on the pharmacokinetics of doxorubicin in dogs with lymphoma.

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.

Evaluation of transdermal application of glipizide in a pluronic lecithin gel to healthy cats.

OBJECTIVE: To evaluate plasma glipizide concentration and its relationship to plasma glucose and serum insulin concentrations in healthy cats administered glipizide orally or transdermally. ANIMALS-15 healthy adult laboratory-raised cats. PROCEDURE: Cats were randomly assigned to 2 treatment groups (5 mg of glipizide, PO or transdermally) and a control group. Blood samples were collected 0, 10, 20, 30, 45, 60, 90, and 120 minutes and 4, 6, 10, 14, 18, and 24 hours after administration to determine concentrations of insulin, glucose, and glipizide. RESULTS: Glipizide was detected in all treated cats. Mean +/- SD transdermal absorption was 20 +/- 14% of oral absorption. Mean maximum glipizide concentration was reached 5.0 +/- 3.5 hours after oral and 16.0 +/- 4.5 hours after transdermal administration. Elimination half-life was variable (16.8 +/- 12 hours orally and 15.5 +/- 15.3 hours transdermally). Plasma glucose concentrations decreased in all treated cats, compared with concentrations in control cats. Plasma glucose concentrations were significantly lower 2 to 6 hours after oral administration, compared with after transdermal application; concentrations were similar between treatment groups and significantly lower than for control cats 10 to 24 hours after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Transdermal absorption of glipizide was low and inconsistent, but analysis of our results indicated that it did affect plasma glucose concentrations. Transdermal administration of glipizide is not equivalent to oral administration. Formulation, absorption, and stability studies are required before clinical analysis can be performed. Transdermal administration of glipizide cannot be recommended for clinical use at this time.

Plasma and skin concentrations of polyunsaturated fatty acids before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis.

OBJECTIVE: To determine essential fatty acid concentrations in plasma and tissue before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis. ANIMALS: 30 dogs with atopic dermatitis. PROCEDURE: Dogs received supplemental flaxseed oil (200 mg/kg/d), eicosapentaenoic acid (EPA; 50 mg/kg/d)-docosahexaenoic acid (DHA; 35 mg/kg/d), or mineral oil as a placebo in a double-blind, placebo-controlled, randomized trial. Clinical scores and plasma and cutaneous concentrations of linoleic acid, arachidonic acid, alpha-linolenic acid (alpha-LLA), EPA, DHA, prostaglandin E2, and leukotriene B4 were determined. RESULTS: Total plasma concentrations of alpha-LLA and EPA increased and those of arachidonic acid decreased significantly with administration of EPA-DHA, and concentrations of alpha-LLA increased with flaxseed oil supplementation; nevertheless, there was no significant change in the concentrations of these fatty acids or eicosanoids in the skin. There was no correlation between clinical scores and plasma or cutaneous concentrations for any of the measured fatty acids or eicosanoids. CONCLUSION AND CLINICAL RELEVANCE: Results indicated that at the dose used, neither the concentrations of fatty acids in skin or plasma nor a decrease in the production of inflammatory eicosanoids was a major factor involved in the mechanism of action in dogs with atopy that responded to fatty acid supplementation.

Canine liver iron, copper, and zinc concentrations and association with histologic lesions.

Concentrations of iron, copper, and zinc were measured in livers of 95 dogs that were suspected of having liver disease. Iron concentrations ranged from 177 to 7,680 ppm (dry weight basis); 54 dogs had iron concentrations greater than the normal concentration of 1,200 ppm. Iron stores were present in Kupffer cells and macrophages but not hepatocytes. The dogs did not have lesions of hemochromatosis. Dogs with high liver iron tended to have high liver copper and inflammatory lesions. High liver copper concentrations usually were associated with hepatocellular necrosis and fibrosis. High liver zinc was found in only 5 animals and was accompanied by histologic inflammatory lesions in one. In humans, increased iron concentration in the liver exacerbates liver damage caused by a variety of insults, and the same may be true for dogs.

The effects of doxapram hydrochloride (dopram-V) on laryngeal function in healthy dogs.

Laryngeal dysfunction is assessed most accurately by direct visualization of the larynx under a light plane of anesthesia. If the plane of anesthesia used is too deep, laryngeal structures may appear paralyzed and remain in a paramedian position. Doxapram hydrochloride is a known respiratory stimulant. We hypothesized that doxapram would significantly increase intrinsic laryngeal motion in healthy anesthetized dogs. The goal of this study was to evaluate the effect of doxapram on the area of rima glottidis (RG) in healthy dogs. Thirty healthy dogs were studied. Dogs were premedicated with butorphanol tartrate (0.22 mg/kg IV), acepromazine maleate (0.05 mg/kg SC), and glycopyrrolate (0.005 mg/kg SC), followed by induction with propofol (4 mg/kg IV). Intrinsic laryngeal motion observed in each dog was recorded on videotape after induction. Doxapram then was administered (2.2 mg/kg IV) and respirations again were recorded. Representative breaths for each dog were photographed during 4 phases of respiration (inspiration at rest, inspiration with doxapram, expiration at rest, and expiration with doxapram). The area of the RG then was calculated by using a computer-assisted analysis program. Results of each category were compared by using a 1-way analysis of variance; P < or = .05 was considered significant. Doxapram visibly increased respiratory effort, and was associated with increased intrinsic laryngeal motion. Compared to the resting state, the area of the RG was significantly increased after doxapram administration during both inspiration and expiration. We propose the routine use of doxapram during laryngoscopy to increase intrinsic laryngeal motion and aid in the diagnosis of laryngeal dysfunction.

Effects of dietary flaxseed oil supplementation on equine plasma fatty acid concentrations and whole blood platelet aggregation.

An 18-week feeding trial was performed to investigate the effects of an omega-3 (n-3) fatty acid-enriched ration on plasma fatty acid concentrations and platelet aggregation in healthy horses. Flaxseed oil served as the source of the n-3 fatty acid alpha-linolenic acid (ALA). Twelve horses were fed dietary maintenance requirements using a complete pelleted ration (80%) and timothy grass hay (20%) for a 2-week acclimation period before being randomly assigned either to a treatment (group 1) or control (group 2) group. Group 2 horses (n = 6) were fed the diet described in the acclimation period, whereas group I horses (n = 6) were fed a 10% flaxseed oil-enriched complete pellet (80%) and grass hay (20%). Biological samples and physical measurements were collected at one point during the acclimation period (week 0) and every 4 weeks thereafter (weeks 4, 8, 12, and 16). Body weight, CBC (including platelet count), plasma fibrinogen. electrolyte (Na, K, and Cl) concentrations, and biochemical profile enzyme activities (aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, and creatine kinase) did not change markedly with diet. Platelet aggregation was not altered by the supplementation of flaxseed oil in these healthy horses, although increases in plasma cis-polyunsaturated 18-carbon fatty acids C18:3; n-3 (ALA) and C18:2; n-6 (linoleic acid), biologically active C20:5; n-3 (eicosapentaenoic acid [EPA]), and malondialdehyde (MDA) were evident. There were no marked decreases in C20:4; n-6 (arachidonic acid [AA]) or increases in C22:6; n-3 (docosahexaenoic acid [DHA]), signifying that flaxseed oil may have had a high percentage of omega-6 (n-6) fatty acids as well as n-3 fatty acids, and this relatively high n-6: n-3 fatty acid ratio may have affected the biochemical effect of n-3 fatty acids. In healthy horses supplemented with flaxseed oil, platelet aggregation was not altered, which may have been due to the limited biologic effect in healthy subjects or the inability of flaxseed oil to induce the necessary biochemical effect of replacing n-6 fatty acids with n-3 types.

Matrix metalloproteinase activity in tumor, stromal tissue, and serum from cats with malignancies.

Matrix metalloproteinases (MMPs) are enzymes that play key roles in angiogenesis, tumor invasion, and metastasis in a wide variety of species. The purpose of this study was to evaluate pro and active MMP 2 and 9 concentrations in tumor, normal stromal tissue, and serum from tumor-bearing cats. We hypothesized that serum concentrations of pro and active forms of MMPs 2 and 9 would be predictive of MMP concentrations in tumor tissue and that these MMP concentrations would correlate with the histopathologic grade of the malignancies. Pro and active forms of MMPs 2 and 9 were determined by gelatin zymography and subsequent computerized densitometry from tumor and nearby stromal tissue and serum from 49 cats with various malignancies. The serum concentrations of MMPs from these tumor-bearing cats were compared with serum concentrations of MMPs from 44 normal cats of similar age and gender. Measurable concentrations of MMPs 2 and 9 were found within tumor, stromal, and serum samples. Mean concentrations of total pro and active MMPs 2 and 9 within tumor tissue were significantly higher (P values <.0001, .0031, <.001, and .0064, respectively) when compared with stromal tissue from the same animals. Serum MMP concentrations from tumor-bearing cats were higher than those from normal cats. Poor correlation was found between serum MMP concentrations and tissue MMP concentrations of increasing histologic grades of malignancies.

Menhaden oil administration to dogs treated with radiation for nasal tumors demonstrates lower levels of tissue eicosanoids.

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) or menhaden oil may reduce inflammatory eicosanoids (prostaglandin E2, thromboxane B2, leukotriene B4, and 11-dehydro thromboxane B2), matrix metalloproteinases (MMPs), and blood lactate in dogs with nasal carcinomas receiving radiation therapy. We hypothesized that menhaden oil would reduce inflammation from radiation damage and lower blood lactate levels in dogs with nasal carcinoma. In a randomized, double-blind, placebo-controlled clinical study, 12 dogs with malignant carcinomas of the nasal cavity were given dietary menhaden oil (DHA and EPA) or soybean oil (control) and then received radiation therapy. Megavoltage radiation was delivered in 18 fractions to a total dose of 56 Gy. Blood levels of DHA, EPA, insulin, glucose, lactic acid, and MMPs 2 and 9; resting energy expenditure; and inflammatory eicosanoids from nasal biopsies were measured throughout radiation therapy. Samples were obtained from each patient 1 week before the start of radiation therapy, at start of radiation, and 7, 18 (end of radiation therapy), and 42 days after radiation was initiated. Dogs that are fed with menhaden oil had significantly (P < .05) higher plasma concentration of DHA by 500% and EPA by 200% and had significantly lower tissue inflammatory eicosanoids and decreased resting energy expenditure by 20% when compared with controls. Increased plasma DHA was significantly associated (P < .05) with decreased plasma lactic acid and MMPs. These data may suggest that dietary fish oil could reduce some detrimental inflammatory eicosanoids and metabolic consequences of radiation therapy.

Polyunsaturated Fatty Acid dietary supplementation induces lipid peroxidation in normal dogs.

Polyunsaturated fatty acids (PUFAs) have anti-inflammatory effects at low concentrations; however increased dietary consumption may conversely increase susceptibility to oxidation by free radicals. The objective of this study was to determine the effects of PUFAs on selective oxidative injury and inflammatory biomarkers in canine urine and serum. Dogs (n = 54) consumed a diet supplemented with 0.5% conjugated linoleic acid/dry matter, 1.0% conjugated linoleic acid/dry matter, or 200 mg/kg docosahexaenoic acid/eicosapentaenoic acid for 21 days. All dogs exhibited significantly increased plasma PUFA concentrations. All dogs had significant elevations in urinary F(2a) isoprostane concentration, though dogs consuming a diet containing 1.0% conjugated linoleic acid/dry matter had the highest increase (P = .0052). Reduced glutathione concentrations within erythrocytes decreased significantly in all three dietary treatment groups (P = .0108). Treatment with diets containing 1.0% conjugated linoleic acid/dry matter resulted in the greatest increase in oxidant injury. Caution should be exercised when supplementing PUFAs as some types may increase oxidation.