Essential fatty acids supplementation in different-stage atopic dogs fed on a controlled diet

The aim of this trial was to evaluate the effects of polyunsaturated fatty acid (PUFA) supplementation in different-stages atopic dogs fed on a controlled diet. Twenty-two non-seasonal atopic dogs of different breeds and ages were included in the 2-month trial. All the patients were given an essential fatty acid (EFA) supplementation [17 mg/kg eicosapentaenoic acid (EPA) + 5 mg/kg docosahexaenoic acid (DHA) + 35 mg/kg gammalinolenic acid (GLA)], the global (diet + supplementation) omega-6 to omega-3 ratio was 5.5-1. Two groups of dogs were considered: group A 'pre-immunotherapy' (15 cases) included dogs with early stages atopy, which had not been submitted to any treatment yet; group B 'post-immunotherapy' (seven cases) included dogs with chronic atopy immunotherapy non-responsive. Clinical evaluations were performed at the beginning, on day 30 and at the end of the trial. Blood serum fatty acids profile was determined at the beginning and at the end of the study. Better clinical results were obtained in group A, a great difference was found between the two groups on pruritus score. Serum arachidonic acid (AA) was significantly lower at the end of the trial in group A while GLA was significantly higher in group B. We hypothesized that different-stages atopic dogs could have different response to EFA supplementation, maybe because of a different fatty acids metabolism. Early stages cases seem to be more responsive to EFA supplementation.     

Dietary fish oil supplementation affects serum fatty acid concentrations in horses

Thirteen horses of Thoroughbred or Standardbred breeding were used to study the effect of dietary fish oil supplementation on blood lipid characteristics. Horses were assigned to either fish oil (n = 7) or corn oil (n = 6) treatment groups for 63 d. The fish oil contained 10.8% eicosapentaenoic acid (EPA) and 8% docosahexaenoic acid (DHA). Each horse received timothy hay and a mixed-grain concentrate at rates necessary to maintain BW. Oil (corn or fish) was top-dressed on the concentrate daily at a rate of 324 mg/ kg of BW. The n-6:n-3 ratio was approximately 3.6:1 for horses receiving the corn oil diet and 1.4:1 for horses receiving the fish oil diet. Horses were exercised 5 d/wk during the study. Before supplementation, there was no difference in the concentrations of any serum fatty acids between the 2 treatment groups. The mean basal concentrations of EPA and DHA on d 0 were 0.04 and 0.01 mg/mL, respectively. After 63 d, horses receiving the fish oil treatment, but not those receiving the corn oil treatment, had increased concentrations of EPA and DHA (P <0.05). Fish oil supplementation for 63 d also increased the concentrations of C22:0, C22:1, and C22:5 fatty acids (P <0.05). Overall, horses receiving fish oil had a decreased concentration of n-6 fatty acids (P <0.05) and a greater concentration of n-3 fatty acids (P <0.01), resulting in a lower n-6:n-3 fatty acid ratio after 63 d (P <0.05). Serum cholesterol concentrations increased (P <0.05) during the supplementation period in horses receiving the corn oil but not in horses receiving the fish oil. Compared with horses receiving corn oil, horses receiving fish oil had lower serum triglycerides at d 63 (P <0.05). These results demonstrate that 63 d of fish oil supplementation at 324 mg/kg of BW was sufficient to alter the fatty acid profile and blood lipid properties of horses receiving regular exercise.     

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.     

The effect of different concentrations of linseed oil or fish oil in the maternal diet on the fatty acid composition and oxidative status of sows and piglets

N‐3 polyunsaturated fatty acids (PUFA) are essential for foetal development. Hence, including n‐3 PUFA in the sow diet can be beneficial for reproduction. Both the amount and form (precursor fatty acids vs. long chain PUFA) of supplementation are important in this respect. Furthermore, including n‐3 PUFA in the diet can have negative effects, such as decreased arachidonic acid (ARA) concentration and increased oxidative stress. This study aimed to compare the efficacy to increase eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in the piglet, when different concentrations of linseed oil (LO, source of precursor α‐linolenic acid) or fish oil (FO, source of EPA and DHA) were included in the maternal diet. Sows were fed a palm oil diet or a diet including 0.5% or 2% LO or FO from day 45 of gestation until weaning. Linoleic acid (LA) was kept constant in the diets to prevent a decrease in ARA, and all diets were supplemented with α‐tocopherol acetate (150 mg/kg) and organic selenium (0.4 mg/kg) to prevent oxidative stress. Feeding 0.5% LO or 0.5% FO to the sows resulted in comparable EPA concentrations in the 5‐day old piglet liver, but both diets resulted in lower EPA concentrations than when 2% LO was fed. The highest EPA concentration was obtained when 2% FO was fed. The DHA level in the piglet liver could only be increased when FO, but not LO, was fed to the sows. The 2% FO diet had no advantage over the 0.5% FO diet to increase DHA in the piglet. Despite the constant LA concentration in the sow diet, a decrease in ARA could not be avoided when LO or FO were included in the diet. Feeding 2% FO to the sows increased the malondialdehyde concentration (marker for lipid peroxidation) in sow plasma, but not in piglets.     

Circulating fatty acid profiles in response to three levels of dietary omega-3 fatty acid supplementation in horses

Fatty acids of the n-3 type confer health benefits to humans and other species. Their importance to equine physiology could include improved exercise tolerance, decreased inflammation, and improved reproductive function. The circulating fatty acid profile and the acquisition and washout of fatty acids in response to n-3 supplementation were determined for horses in the current study. A fatty acid supplement high in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid was fed to deliver EPA plus DHA at 0 (control), 10, 20, or 40 g/d to 16 mares (n = 4/group) for 28 d. Plasma was collected at -11, 3, 7, 10, 16, 23, 30, 37, 44, 70, and 87 d relative to the beginning of supplementation. Plasma was analyzed for the presence of 35 fatty acids by gas chromatography. Plasma EPA and DHA increased (P < 0.05) in a dose-responsive manner by 3 d of feeding and reached peak concentrations by 7 d. Peak EPA and DHA concentrations of the 40 g/d supplement group were approximately 13x and 10x those of controls, respectively. Plasma EPA and DHA demonstrated a steep decline (P < 0.05) from peak values by 9 d after cessation of supplementation and were near presupplementation values by 42 d. Omega-3 supplementation also increased (P < 0.05) concentrations of fatty acids C14:0, C17:1n-7, C18:1trans-11, C18:3n-6, C18:4n-3, C20:3n-6, C20:4n-6, and C22:5n-3 and decreased (P < 0.05) concentrations of C18:1cis-9 fatty acid. Seasonal effects, apparently unrelated to supplementation and likely due to the availability of fresh forage, were also noted. Unlike ruminants, there were no detectable concentrations of CLA in equine plasma. These results indicate that the circulating fatty acid milieu in horses can be influenced through targeted supplementation. Possible implications of increased n-3 plasma and tissue concentrations on specific physiological function in the equine remain to be elucidated.     

Polyunsaturated fatty acids influence inflammatory markers in a cellular model for canine osteoarthritis

Although it is well recognized that dietary supplementation with fish oil improves clinical symptoms in dogs suffering from osteoarthritis, the molecular basis for the dietary benefit is not yet completely resolved in dogs. This study was designed to further clarify how polyunsaturated fatty acids (PUFA) affect key factors of cartilage degeneration in a canine cell culture system mimicking osteoarthritis. Canine chondrocytes were incubated either without or with 10 μm of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) or 3.6 μm ibuprofen (Ibu) as positive control for 6 days. After the supplementation, cells were stimulated with 10 ng/ml interleukin‐1β (IL‐1β) for another 48 hr to induce osteoarthritic changes, or left unstimulated. We analysed fatty acid uptake via gas–liquid chromatography, nitric oxide (NO) production via Griess assay, prostaglandin E (PGE) production via ELISA and relative gene expression of several cartilage matrix proteinases, inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 via RT‐qPCR. After supplementation, the chondrocytes rapidly incorporated the PUFA into their fatty acid pools. The stimulation with IL‐1β caused a marked increase of most of the inflammatory markers measured. N‐3 PUFA EPA reduced IL‐induced gene expression of iNOS and corresponding production of NO. N‐6 PUFA AA also decreased iNOS and NO, but furthermore lowered gene expression of matrix metalloproteinase‐3. On the other hand, AA upregulated the aggrecanase ADAMTS‐5 and augmented the release of PGE. The effect of n‐3 PUFA DHA turned out to be negligible. Our results reveal molecular mechanisms by which PUFA affect degenerative joint disease in dogs. Of particular importance is that not only EPA but also AA decreased several inflammatory markers in our model. Thus, we conclude that an appropriate balance of both n‐3 and n‐6 fatty acids deserves more attention in dietary interventions.     

Canine plasma and erythrocyte response to a docosahexaenoic acid-enriched supplement: characterization and potential benefits

Results of this study confirm that dietary supplementation in dogs with a natural source of omega-3 fatty acids (salmon oil), with a docosahexaenoic acid:eicosapentaenoic acid (DHA:EPA) ratio of 1.5:1, increases plasma and red blood cell levels of these fatty acids. Supplementation with this DHA-enriched oil improves the long-chain polyunsaturated fatty acid omega-6:omega-3 (n-6:n-3) ratio, which may benefit dogs of all ages. Studies describing some of the neurologic, renal, cardiovascular, immune, and musculoskeletal effects of elevated blood levels of n-3 fatty acids, especially DHA, are reviewed. The importance of providing an enriched source of DHA, instead of its shorter precursors, is emphasized.     

Response of plasma fatty acid profiles to changes in dietary n‐3 fatty acids and its correlation with erythrocyte fatty acid profiles in dogs

An elevated level of long‐chain n‐3 fatty acids (FA) in tissue membranes has a positive influence on the progression and treatment of many diseases. Therefore, dietary supplementation of n‐3 FA is recommended in some diseases. Even though n‐3 FA are absorbed readily from the diet, their incorporation into tissues may be compromised in diseased animals. In a clinical setting, it is desirable to monitor the success of dietary intervention. Plasma FA as well as erythrocyte membrane (EM) FA can be used to monitor dietary FA intake. This study compares FA from EM and plasma with regard to their reaction time and reliability for monitoring dietary changes of tissue FA profiles in dogs. Thirty dogs were divided into three groups and fed for 12 weeks. The control group (CONT) was fed a commercial standard diet low in n‐3 FA. One group received the standard diet and 85 mg/kg body weight of a docosahexaenoic acid (DHA) concentrate (ADD). The third group was fed a commercial dog food containing fish oil (FO), which is rich in eicosapentaenoic acid (EPA). EM and plasma FA profiles were analysed by GC separately. Data on EM FA were published recently. n‐3 FA in plasma reached the new level after 2 weeks (8 weeks in EM). Dietary differences between DHA and EPA are obvious after 1 week already. The concomitant decrease in plasma n‐6 FA differed between ADD and FO. In general, the correlation of n‐6 FA between plasma and EM was low. We therefore conclude that analysis of plasma FA is sufficient for monitoring a diet‐induced increase in tissue n‐3 FA in dogs. However, EM FA should be analysed if the effect of dietary intervention on tissue n‐6 FA is important.     

Omega-3 fatty acids in the gravid pig uterus as affected by maternal supplementation with omega-3 fatty acids

Two experiments evaluated the ability of maternal fatty acid supplementation to alter conceptus and endometrial fatty acid composition. In Exp. 1, treatments were 1) the control, a corn-soybean meal diet; 2) flax, the control diet plus ground flax (3.75% of diet); and 3) protected fatty acids (PFA), the control plus a protected fish oil source rich in n-3 PUFA (Gromega, JBS United Inc., Sheridan, IN; 1.5% of diet). Supplements replaced equal parts of corn and soybean meal. When gilts reached 170 d of age, PG600 (PMSG and hCG, Intervet USA, Millsboro, DE) was injected to induce puberty, and dietary treatments (n = 8/treatment) were initiated. When detected in estrus, gilts were artificially inseminated. On d 40 to 43 of gestation, 7 gilts in the control treatment, 8 gilts in the PFA treatment, and 5 gilts in the flax treatment were pregnant and were slaughtered. Compared with the control treatment, the flax treatment tended to increase eicosapentaenoic acid (EPA: C20:5n-3) in fetuses (0.14 vs. 0.25 +/- 0.03 mg/g of dry tissue; P = 0.055), whereas gilts receiving PFA had more (P < 0.05) docosahexaenoic acid (DHA: C22:6n-3) in their fetuses (5.23 vs. 4.04 +/- 0.078 mg/g) compared with gilts fed the control diet. Both the flax and PFA diets increased (P < 0.05) DHA (0.60, 0.82, and 0.85 +/- 0.078 mg/g for the control, flax, and PFA diet, respectively) in the chorioallantois. In the endometrium, EPA and docosapentaenoic acid (C22:5n-3) were increased by the flax diet (P < 0.001; P < 0.05), whereas gilts receiving PFA had increased DHA (P < 0.001). The flax diet selectively increased EPA, and the PFA diet selectively increased DHA in the fetus and endometrium. In Exp. 2, gilts were fed diets containing PFA (1.5%) or a control diet beginning at approximately 170 of age (n = 13/treatment). A blood sample was collected after 30 d of treatment, and gilts were artificially inseminated when they were approximately 205 d old. Conceptus and endometrial samples were collected on d 11 to 19 of pregnancy. Plasma samples indicated that PFA increased (P < 0.005) circulating concentrations of EPA and DHA. Endometrial EPA was increased (P < 0.001) for gilts fed the PFA diet. In extraembryonic tissues, PFA more than doubled (P < 0.001) the EPA (0.13 vs. 0.32 +/- 0.013 mg/g) and DHA (0.39 vs. 0.85 +/- 0.05 mg/g). In embryonic tissue on d 19, DHA was increased (P < 0.05) by PFA (0.20 vs. 0.30 +/- 0.023 mg/g). Supplementing n-3 PUFA, beginning 30 d before breeding, affected endometrial, conceptus, and fetal fatty acid composition in early pregnancy. Dynamic day effects in fatty acid composition indicate this may be a critical period for maternal fatty acid resources to affect conceptus development and survival.     

The Effects of n-3 Fatty Acid Supplementation on Bleeding Time, Plasma Fatty Acid Composition, and In Vitro Platelet Aggregation in Cats

Dietary supplementation with fish and fish oils rich in the n-3 fatty acids eicosapentaenoic acid ( EPA ) and docosahexaenoic acid (DHA) has been shown to alter eicosanoid metabolism and impair platelet function in several species. As an initial step in evaluating the antithrombotic effect of these n-3 fatty acids in cats, purified EPA and DHA were administered daily to 8 clinically normal cats for 2 months. Platelet function was evaluated biweekly by determining mucosal bleeding time and in vitro platelet aggregation parameters. Plasma fatty acid profiles were obtained before fish oil supplementation and at the termination of the study. In spite of significant increases ( P < .0001) in the plasma concentrations of EPA and DHA after n-3 fatty acid supplementation, there were no significant changes in platelet aggregation or bleeding times. Although it is tempting, based on extrapolation of data from other species, to recommend dietary supplementation with fish oil for cats prone to arterial thromboembolism, these results indicate that administration of large doses of purified EPA and DHA once daily does not inhibit platelet function in normal cats and is unlikely to prevent thrombosis in cats with cardiovascular disease. Additional studies are recommended to ascertain whether more frequent administration of these purified n-3 fatty acids or continual feeding of diets high in n-3 fatty acid content will impair platelet function.     

Effects of two different dietary sources of long chain omega-3, highly unsaturated fatty acids on incorporation into the plasma, red blood cell, and skeletal muscle in horses

The objective of this study was to examine the effects of different sources of dietary omega-3 (n-3) fatty acid supplementation on plasma, red blood cell, and skeletal muscle fatty acid compositions in horses. Twenty-one mares were blocked by age, BW, and BCS and assigned to 1 of 3 dietary treatments with 7 mares per treatment. Dietary treatments were: 1) control or no fatty acid supplement (CON), 2) 38 g of n-3 long chain, highly unsaturated fatty acid (LCHUFA) supplement/d provided by algae and fish oil (MARINE) containing alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), and 3) 38 g of n-3 LCHUFA supplement/d provided by a flaxseed meal (FLAX) containing ALA. Each supplement was added to a basal diet consisting of hay and barley and was fed for 90 d. Blood samples and muscle middle gluteal biopsies were taken at d 0, 30, 60 and 90 of supplementation. Plasma, red blood cell and skeletal muscle fatty acid profiles were determined via gas chromatography. Plasma linoleic acid (LA) and ALA were at least 10 and 60% less (P < 0.01), respectively, in the MARINE compared with the FLAX and CON groups. Plasma EPA and DHA were only detected in the MARINE group, and EPA increased 40% (P < 0.001) from d 30 to 60, and DHA 19% (P < 0.01) from d 30 to 90. Red blood cell LA and ALA were not different among treatments. Red blood cell EPA and DHA were only detected in the MARINE group, where EPA increased 38% (P < 0.01) from d 30 to 60, and DHA increased 56% (P < 0.001) between d 30 and 90. Skeletal muscle LA was at least 17% less (P < 0.001) in the MARINE group compared with the other treatments. Skeletal muscle ALA was 15% less (P = 0.03) in the MARINE group compared with FLAX and CON groups. Skeletal muscle EPA was at least 25% greater (P < 0.001) in MARINE group compared with other treatments and increased (P < 0.001) by 71% from d 30 to 60. Skeletal muscle DHA was at least 57% greater (P < 0.001) in the MARINE group compared with other groups and increased (P < 0.001) by 40% between d 30 and 90. As far as the authors are aware, this is the first study to demonstrate that dietary fatty acid supplementation will affect muscle fatty acid composition in horses. Incorporation of n-3 LCHUFA into blood and muscle depends directly on dietary supply of specific fatty acids.     

Dietary (n-3) fatty acids from menhaden fish oil alter plasma fatty acids and leukotriene B synthesis in healthy horses

The study objective was to determine the effect of feeding corn oil or fish oil to horses on plasma fatty acid profiles and leukotriene B (LTB) synthesis by stimulated peripheral blood neutrophils. Two groups of horses (n = 5) were randomly assigned to diets supplemented with either 3.0% (by weight) corn oil or fish oil for a period of 14 weeks. The ratio of (n-6) to (n-3) fatty acids in oil supplements was 68.1:1 for corn oil and 0.12:1 for fish oil. Production of LTB4 and LTB, by peripheral blood neutrophils stimulated with calcium ionophore A23187 and plasma cholesterol, triacylglycerol, and alpha-tocopherol concentrations were measured. At 12 weeks, horses fed fish oil had increased plasma concentrations of eicosapentaenoic acid (27-fold; 8.5 versus 0.3 g/100 g fatty acids; P < .0001), docosahexaenoic acid (34-fold; 5.1 versus 0.1 g/100 g fatty acids; P < .0001), and arachidonic acid (8.3-fold; 4.1 versus 0.5 g/100 g fatty acids; P < .0001) compared with horses fed corn oil. Neutrophils from horses fed fish oil produced 78-fold (P = .01) more LTB5 and 9.5-fold (P = .003) more LTB4 compared with predietary levels, and 17.6-fold (P = .01) and 3.3-fold (P = .02), respectively, more than horses fed corn oil, and the ratio of LTB5 to LTB4 concentrations was 4.0-fold (P = .002) higher in horses fed fish oil. This study suggests that dietary polyunsaturated fatty acids modulate the leukotriene inflammatory response of horses. If the ratio of LTB5 to LTB4 concentrations is important in determining how inflammatory processes are mediated, then fish oil supplementation may have value in treatment of equine inflammatory diseases.     

Effects of oral sunflower oil and olive oil on serum and cutaneous fatty acid concentrations in dogs.

The effects of dietary fatty acids on serum and cutaneous fatty acids of healthy dogs were evaluated under controlled conditions. Beagle puppies (n = 12) were fed a standard diet supplemented with sunflower oil (group A), olive oil (group B) or no supplementation (group C) for 12 weeks. There were no significant differences in food intake or growth rates between the three groups. Dogs in group A had significant increases (P < 0.05) in serum 18:2n6 (linoleic acid) and 20:3n6 (dihomo-gamma-linolenic acid), and cutaneous 18:2n6 with significant decreases in serum 20:4n6 (arachidonic acid) and cutaneous 18:1n9 (oleic acid) and 18:3n3 (alpha-linolenic acid). Dogs in group B had significant increases in serum 18:1n9, 20:3n6 and cutaneous 18:1n9 with decreases in serum 20:4n6, 22:4n6, 22:5n3 and 22:5n6, and cutaneous 18:2n6, 18:3n3 and 20:4n6. There were no significant changes in serum or cutaneous fatty acids for the dogs in group C. This study demonstrates that fatty acid supplements can be used to alter the serum and cutaneous fatty acid compositions of dogs.     

Influence of dietary long-chain n-3 fatty acids from menhaden fish oil on plasma concentrations of alpha-tocopherol in geriatric beagles

OBJECTIVE: To determine effects of dietary n-3 fatty acids from Menhaden fish oil on plasma alpha-tocopherol concentrations in Beagles. ANIMALS: 32 female Beagles. PROCEDURE: For 82 days, dogs were fed diets that contained 1 of 2 ratios of n-6:n-3 fatty acids (40:1 [low n-3] and 1.4:1 [high n-3]) and 1 of 3 concentrations of all-rac-alpha-tocopheryl acetate (low, 17 mg/kg of diet; medium, 101 mg/kg; and high, 447 mg/kg) in a 2 X 3 factorial study. RESULTS: Diets high in n-3 fatty acids significantly increased total content of n-3 fatty acids in plasma (17.0 g/100 g of fatty acids), compared with low n-3 diets (2.02 g/100 g of fatty acids). Mean +/- SEM plasma concentration of cholesterol was significantly lower in dogs consuming high n-3 diets (4.59 +/- 0.48 mmol/L), compared with dogs consuming low n-3 diets (5.71 +/- 0.48 mmol/L). A significant interaction existed between the ratio for n-6 and n-3 fatty acids and amount of alpha-tocopheryl acetate in the diet (plasma alpha-tocopherol concentration expressed on a molar basis), because the plasma concentration of alpha-toco-pherol was higher in dogs consuming low n-3 diets, compared with those consuming high n-3 diets, at the 2 higher amounts of dietary alpha-tocopheryl acetate. Plasma alpha-tocopherol concentration expressed relative to total lipid content did not reveal effects of dietary n-3 fatty acids on concentration of alpha-tocopherol. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma alpha-tocopherol concentration is not dependent on dietary ratio of n-6 and n-3 fatty acids when alpha-tocopherol concentration is expressed relative to the total lipid content of plasma.     

The Influence of long-chain polyunsaturated fatty acids on total lipid fatty acid composition of a canine mastocytoma cell line

Cutaneous mast cells are considered as key immune effectors in the pathogenesis of canine atopic dermatitis (CAD). These cells release immediate-phase and late-phase mediators of inflammation. Dietary fatty acids are incorporated in cellular membranes and seem to influence mediator production and release. A dietary intervention with n6- and n3-fatty acids is thought to alleviate clinical symptoms in atopic dogs. The purpose of this study was to examine the effects of n6- and n3-fatty acids on the fatty acid composition of canine mastocytoma cells (C2) as a possible model for CAD. The C2 was cultured in a basic medium called Dulbecco's modified Eagle's medium (DEH) or with additional 14 mum linoleate (C18:2n6, DEH-LA), gamma-linolenate (C18:3n6, DEH-GLA), arachidonate (C20:4n6, DEH-AA), alpha-linolenate (C18:3n3, DEH-LnA), eicosapentaenoate (C20:5n3, DEH-EPA) or docosahexaenoate (C22:6n3, DEH-DHA). Cell growth was examined for 11 days in all media. Cell growth increased from days 1 to 8 and decreased thereafter in all media conditions. The fatty acids supplied did not influence cell growth. The cells were harvested after 8 days for fatty acid analysis. The fatty acid composition was determined by gas chromatography after extraction and trans-esterification of the lipids. The added fatty acids increased the concentration of these fatty acids in C2 differently (LA 4.9-fold, GLA 6.9-fold, AA 6-fold, LNA 9.3-fold, EPA 6.5-fold and DHA 8.4-fold). Furthermore, elongated and Delta6-desaturated products of the corresponding fatty acids were significantly elevated. However, Delta5-desaturated products were not measurable. These results let us assume that C2 has no measurable activity of the Delta5-desaturase. In case the low activity of Delta5-desaturase is one of the mechanisms underlying the pathogenesis of CAD, C2 seems to be an adequate model for investigations in CAD.     

Dietary fish oil alters the lysophospholipid metabolomic profile and decreases urinary 11-dehydro thromboxane B₂ concentration in healthy Beagles

Increased concentrations of dietary fish oil and antioxidants have been shown previously to change circulating concentrations of individual fatty acids (FAs) and vitamin E. The purpose of this study was to further investigate the effects of vitamins E and C, in combination with dietary fish oil, on selected blood and urinary biomarkers. Fifty adult Beagle dogs (mean age 5.3 years, range 1.4-14.2 years) were randomized into five dietary treatment groups for 90 days. All foods were complete and balanced and met the nutrient profiles of AAFCO for adult dogs. For 60 days before study initiation, dogs consumed a pretrial food that contained 74 IU/kg vitaminE and 0mg/kg vitaminC. The five experimental foods were confirmed by analytical methods to contain ≥ 640 IU/kg vitaminE and 130 mg/kg vitaminC (as fed). Experimental foods ranged from low levels of EPA and DHA (pretrial food and lowest experimental food had 0.01% EPA and no detectable DHA) to the highest experimental food with 0.25% EPA and 0.17% DHA. Serum was analyzed for FAs, vitamin E, and cholesterol concentrations; urine was analyzed for 11-dehydro thromboxane B(2) (TXB(2)). Serum was also used for metabolomic analysis. FA intake ranged from 0.02 g/day EPA and 0.02 g/day DHA to 0.58 g/day EPA and 0.39 g/day DHA. Increasing dietary concentrations of EPA and DHA resulted in increased serum concentrations of EPA and DHA in a dose-dependent fashion. Greater dietary vitamin E intake resulted in increased serum vitamin E concentrations (P<0.01). Higher serum cholesterol was also associated with higher serum vitamin E concentrations (P<0.01). In turn, changes in serum cholesterol concentration were associated with diet-induced changes in serum FA concentrations (all P<0.01). At the beginning of the dietary treatment period the most significant predictor of urine 11-dehydro TXB(2) concentration was age, followed by lean-body mass. After dietary treatment with different amounts of fish oil, age (increases 11-dehydro TXB(2)) was followed by EPA concentration as a significant negative predictor of urine 11-dehydro TXB(2) concentration (increasing serum concentrations of EPA decrease 11-dehydro TXB(2)), and then lean-body mass (decreases 11-dehydro TXB(2)). Serum docosahexaenoyl-glycerophosphocholine concentration was increased by feeding fish oil in a dose-response manner. In summary, serum vitamin E concentration is enhanced primarily by feeding vitamin E and secondarily by serum cholesterol concentration. When feeding diets enriched with fish oil, the major negative predictor of urinary 11-dehydro TXB(2) concentration is serum EPA concentration. Plasma lysophospholipids can be dynamically regulated by dietary fish oil supplementation.     

Erythrocyte and plasma fatty acid patterns in dogs with atopic dermatitis and healthy dogs in the same household

Recent studies have indicated that dogs with canine atopic dermatitis (CAD) may have a disorder of fatty acid metabolism: possibly low or absent activity of delta6-desaturase or delta5-desaturase, or both. To clarify this possibility, we examined the erythrocyte and plasma fatty acid patterns of 8 dogs with CAD and their 8 healthy housemates. Atopic dermatitis was diagnosed according to the criteria proposed by Willemse; other causes of dermatitis were excluded clinically and by appropriate tests. Erythrocyte ghosts were prepared from blood samples. Membrane lipids were extracted and separated by thin-layer chromatography. From plasma and lipid fractions, fatty acid content was determined by gas chromatography. In erythrocytes, but not in plasma, we observed significant differences in the fatty acid pattern that suggested a reduction in the n6 fatty acid products of the delta6- and delta5-desaturases in dogs with atopic dermatitis when compared with healthy housemates.     

Effects of dietary n-6 and n-3 fatty acids and vitamin E on the immune response of healthy geriatric dogs

OBJECTIVE: To determine the effect of dietary n-6 to n-3 fatty acid ratios and alpha-tocopheryl acetate concentration on immune functions andT cell subpopulations in healthy dogs. ANIMALS: Thirty-two 7- to 10-year old female Beagles. PROCEDURE: For 17 weeks, dogs were fed food that contained low (1.4:1) or high (40:1) ratios of n-6 to n-3 fatty acids in combination with 3 concentrations of all rac-alpha-tocopheryl acetate (low, 17 mg/kg of food; medium, 101 mg/kg; high, 447 mg/kg). Dogs were inoculated twice with a keyhole limpet hemocyanin suspension at 13 and 15 weeks. RESULTS: After 12 weeks, dogs consuming low concentrations of alpha-tocopheryl acetate had lower percentages of CD8+ T cells, compared with dogs consuming medium or high alpha-tocopheryl acetate concentrations. Also, dogs consuming low alpha-tocopheryl acetate concentrations had higher CD4+ to CD8+ T cell ratios. On day 4 of week 15, the percentage of CD8+ T cells was highest in dogs fed medium concentrations of alpha-tocopheryl acetate, compared with other dogs; however, the CD4+ to CD8+ T cell ratio was higher only in dogs fed low concentrations of alpha-tocopheryl acetate with high concentrations of n-3 fatty acids. Dogs consuming low concentrations of n-3 fatty acids with medium concentrations of alpha-tocopheryl acetate had the largest delayed-type hypersensitivity (DTH) skin test response. CONCLUSIONS AND CLINICAL RELEVANCE: An optimum amount of dietary alpha-tocopheryl acetate concentration, regardless of the dietary n-6 to n-3 fatty acid ratio, stimulates the CD8+ T cell population. Effects of an optimum amount of dietary alpha-tocopheryl acetate concentration on the DTH response are blunted by dietary n-3 fatty acids.