A study into the fatty acid content of selected veterinary diets, supplements and fish oil capsules in Australia

BACKGROUND

Dogs with cutaneous diseases often receive supplementation with omega-3 (n-3) and omega-6 (n-6) essential fatty acids (FA), either through their diet or the use of an oral supplement. Labelling on these products is not always clear, especially regarding the total and relative amounts of FA.

OBJECTIVES

To provide clinicians with a breakdown of the FA content of selected veterinary diets, supplements and fish oil capsules so that the daily dose of supplementation can be calculated more easily. Repeated measurements of FA content over time demonstrate whether FA content changes temporally.

METHODS AND MATERIALS

Eight veterinary diets, four veterinary oral FA supplements and four fish oil supplements were analysed for FA content by gas chromatography at days 0, 28 and 56.

RESULTS

The n-6:n-3 ratio varied among the supplement types with the food samples having higher ratios than the liquid supplements and fish oil capsules. The composition of n-3 FA differed between products with some having higher concentrations of the less active n-3 FA alpha-linolenic acid than eicosapentaenoic acid and docosahexaenoic acid. No decreases in FA content over time were detected.

CONCLUSIONS AND CLINICAL RELEVANCE

The results of this study provide the reader with a means to calculate the FA concentrations that their patient is receiving for each product tested, as well as allowing them to compare products for their differences in n-6:n-3 ratios and relative amounts of individual FA molecules. The FA concentrations did not change significantly over 56 days.

Exploring the use of essential fatty acids in veterinary dermatology

BACKGROUND

The aim of the study was to discover the extent of use of essential fatty acids (EFAs) in veterinary practice, conditions used in, preparation of EFA supplement used and rationale for their use and to investigate the awareness of the oxidation of some commercial fish oil supplement preparations.

METHODS

A web-based questionnaire was distributed via email to a dermatology list server and posted to veterinary Facebook groups with questions relating to the use of EFAs, supplement choice, conditions used in, the level of importance of various factors regarding their use and awareness of their oxidation.

RESULTS

There were 309 responses from 32 countries. EFA supplements were used by 92.2 per cent of respondents. The most commonly used preparation of EFA supplementation was veterinary oral supplements (75.1 per cent), followed by veterinary diets (14.4 per cent), shop bought fish oil supplements (7.7 per cent), enhancing the diet with oily fish (2.5 per cent) and finally using a commercial pet food (0.3 per cent). Only 46.3 per cent of respondents who used them were aware of the oxidation of EFAs. Veterinary oral supplements were perceived to be the best preserved, followed by veterinary diets and lastly commercial fish oil supplements.

CONCLUSION

A large number of respondents advised the use of EFAs for veterinary dermatological conditions but less than 50 per cent were aware of the potential for EFAs to oxidise.

Plasma phospholipid fatty acid and ex vivo neutrophil responses are differentially altered in dogs fed fish- and linseed-oil containing diets at the same n-6:n-3 fatty acid ratio

The effect of diets containing either 18-carbon n-3 fatty acids (FA) or 20/22-carbon n-3 FA on canine plasma and neutrophil membrane fatty acid composition, superoxide and leukotriene B₄ and B₅ production when fed at the same n-6:n-3 fatty acid ratio was investigated. Four groups of ten dogs each were fed a low fat basal diet supplemented with safflower oil (SFO), beef tallow (BTO), linseed oil (LSO), or Menhaden fish oil (MHO) for 28 days. Dietary fat provided 40.8% of energy and the n-6:n-3 of the diets were ~100:1, 9.7:1, 0.38:1, and 0.34:1 for the SFO, BTO, LSO and MHO groups, respectively. The MHO and LSO groups had increased incorporation of EPA and DPA in both the plasma and neutrophil membranes compared to the BTO and SFO groups. DHA was observed in the MHO but not in the LSO group. Neutrophils from the MHO diet fed dogs had less LTB₄ and greater LTB₅ than the other three groups. The LSO group also showed a reduction in LTB₄ and greater LTB₅ production compared to the SFO and BTO groups. Both LSO and MHO groups had lower superoxide production compared to the SFO and BTO groups. Diets containing 18 or 20/22 carbon n-3 FA fed at the same n-6:n-3 resulted in differential incorporation of long chain n-3 FA into neutrophil membranes. Thus, fatty acid type and chain length individually affect neutrophil membrane structure and function and these effects exist independent of dietary total n-6:total n-3 FA ratios.

The Influence of Topical Unsaturated Fatty Acids and Essential Oils on Normal and Atopic Dogs

Seven dogs with atopic dermatitis and six normal dogs were treated with a spot-on product containing essential oils and unsaturated fatty acids q 7 days for 8 wk. Seven additional atopic dogs received a daily spray containing similar ingredients to the spot-on. In all dogs, transepidermal water loss (TEWL) was measured before and after treatment using a closed chamber device. In atopic dogs, a validated lesion score (canine atopic dermatitis extent and severity index, CADESI) was determined and pruritus was assessed with a visual analog scale before and after treatment. The mean CADESI scores in atopic dogs decreased with the spot-on (P=0.0043) and with the spray (P=0.0366). Similarly, the pruritus scores decreased with the spot-on (P=0.266) and with the spray (P=0.0177). There was a significant difference between the TEWL values of healthy and atopic dogs on the abdomen (P=0.0181) and back (P=0.0123). TEWL decreased significantly on the back after treatment with the spray (P=0.016), but not on the abdomen (P=0.078). Adverse effects were not observed. The results of this pilot study indicate that topical fatty acids and essential oils are a useful treatment option for canine atopic dermatitis.

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.

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.

Effect of omega-3 fatty acids on canine atopic dermatitis

Twenty-nine dogs were included in a double-blinded, placebo-controlled, randomised trial and were orally supplemented for 10 weeks with either flax oil (200 mg/kg/day), eicosapentaenoic acid (50 mg/kg/day) and docosahexaenoic acid (35 mg/kg/day) in a commercial preparation, or mineral oil as a placebo. For each dog, clinical scores were determined based on a scoring system developed prior to the trial. Total omega-6 and omega-3 intake and the ratio of omega-6:omega-3 (omega-6:3) were calculated before and after the trial. The dogs' clinical scores improved in those supplemented with flax oil and the commercial preparation, but not in the placebo group. No correlation was identified between total fatty acid intake or omega-6:3 ratio and clinical scores. Based on the results of this study, the total intake of fatty acids or the omega-6:3 ratio do not seem to be the main factors in determining the clinical response.

Effect of n-3 fatty acid ratio and dose on clinical manifestations, plasma fatty acids and inflammatory mediators in dogs with pruritus

The use of n-3 fatty acids is often recommended to manage pruritus. The purpose of this study was to determine the effect of various doses of n-3 fatty acids at different n-6:n-3 ratios on plasma fatty acids, clinical response and inflammatory mediators in pruritic dogs. After baseline assessment, dogs were randomly assigned to receive diets varying in both total n-3 and n-6 fatty acid dose and n-6:n-3 ratio. The total clinical score decreased significantly in all four diet groups after 8 weeks with no difference between groups. Plasma fatty acid changes generally mirrored the fatty acid content of the test diets, although alterations appeared to depend on both the dose of n-3 fatty acids and the n-6:n-3 ratio. In this clinical trial, which controlled dietary intake of fatty acids, n-3 fatty acid supplementation did not appear to have an added benefit on clinical signs over thorough clinical management.

The ACVD task force on canine atopic dermatitis (XXIII): are essential fatty acids effective?

Essential fatty acids (EFAs) exhibit the potential to affect allergic inflammation through the modulation of prostaglandin and leukotriene production, the inhibition of cellular activation and cytokine secretion as well as the alteration of the composition and function of the epidermal lipid barrier. Because of these multi-faceted effects, EFA have been proposed for treatment of canine atopic dermatitis (AD) since 1987. To date, more than 20 trials have been performed, reporting the efficacy of either oral EFA supplements or EFA-rich diets. Unfortunately, most of these studies were found to exhibit one or more of the following deficiencies: heterogeneity of diagnoses used as inclusion criteria, short duration of supplementation, lack of randomization of treatment allocation, lack of blinding of investigators and/or owners, lack of placebo or active controls, lack of documentation of plasma or skin EFA profiles during supplementation, as well as lack of standardization of the basal diets or supplements which could have provided additional EFA. Consequently, there is presently insufficient evidence to recommend for or against the use of EFA to control clinical signs of canine AD. Evidence of efficacy must await the performance of blinded, randomized and controlled trials of at least 3 months duration in which diets are identical for all of study subjects. In these trials, clinical efficacy should be evaluated in relation to plasma and cutaneous EFA treatment-induced alterations.