USE OF N-3 AND N-6 PUFA's AS INDIVIDUAL SUPPLEMENTS
Dawn Logas, DVM Diplomat of ACVD
Veterinary Dermatology Center
9901 South Hwy 17-92
Maitland, Florida
Most veterinary fatty acid supplements are combinations of both n-3 and n-6 fatty acids along with various vitamins and minerals. In this article we will discuss supplementation with n-3 or n-6 PUFA's [polyunsaturated fatty acids] individually instead of in combination.
Omega-6 PUFA's are necessary for normal epidermal barrier formation and function and for normal desquamation of the stratum corneum 1. Clinical signs associated with diminished essential fatty acids include increased scaling, alopecia and a dull-dry hair coat 2. Dogs with decreased n-6 PUFA levels may also experience increased waxy keratinaceous debris, both aurally and interdigitally. These signs are secondary to changes in the epidermal and sebum lipid composition such as the inclusion of more n-9 fatly acids. These changes consequently do not allow for normal epidermal barrier formation or desquamation. The changes in desquamation also increase the incidence of bacterial pyodermas in dogs with diminished n-6 PUFA levels.
Most commercial dog foods contain sufficient amounts of n-6 PUFA's to carry out normal bodily functions. In certain situations this is not the case and additional n-6 PUFA's are needed. This can be secondary to a decrease in availability of n-6 PUFA's in the diet or an increase need in certain individuals. Generic dog foods may not have proper amounts of essential or usable n-6 PUFA's. This may also be true of old or improperly stored dry dog food that originally had sufficient n-6 PUFA but prolonged exposure to air, heat and/or moisture causes oxidation of the fatty acids that diminishes their usefulness to the pet.
The reasons for an increased requirement of n-6 PUFA's by an individual are numerous. Certain breeds such as Dobermans and other related short-coated breeds appear to have an increased need in n-6 PUFA's and may not do well on low fat diets. Animals living in extremely dry environments may need extra n-6 PUFA's to maintain their epidermal lipid barrier. Dogs who swim or are bathed often may also need extra n-6 PUFA's to replace epidermal lipids and sebum removed-by chlorine or harsh shampoos.
Dog with chronic dermatoses of any kind can benefit from n-6 PUFA supplementation.
Puritic dermatoses lead to increased turnover of the stratum corneum and loss
of the epidermal barrier lipids. This can cause dry brittle hair and excessive
scaling. In one double blinded study examining the effects of n-3 and n-6 PUFA's
on pruritus, the dogs receiving 6 weeks of n-6 PUFA supplementation were found
to have glossier coats and less scale even though their pruritus did not significantly
change 1. Other dermatoses such as idiopathic seborrhea,
sebaceous adenitis and Vitamin A responsive dermatosis that cause decreased
epidermal transit time and abnormal desquamation may benefit from systemic and/or
topical supplementation of n-6 PUFA's.
The dose of n-6 PUFA's added to the diet ranges from 5 to 30 ml/20lb of body weight. I normally use corn or sunflower oil. For topical therapy many times I will use olive oil (MUFA)
Omega-3 PUFA supplementation is used primarily for its anti-inflammatory properties.
The most common reason for supplementation is adjunctive therapy for pruritic
dermatoses such as atopy and insect hypersensitivity. In one double-blinded
study 9/16 dogs showed at least a 50% improvement in pruritus when supplemented
with n-3 PUFA's 3. Since doing this study, my clinical
opinion is that half the atopic and insect allergic dogs we diagnose improve
with n-3 PUFA supplementation. This improvement is noted in the first 3 to 4
weeks. I have also used n-3 PUFA's in the treatment of lupoid onchodystrophy
and discoid lupus erythematosus with minimal success.
Finally, I use n-3 PUFA's in the treatment of generalized mast cell tumors,
mycosis fungoides and other neoplastic diseases. For squamous cell carcinoma,
mycosis fungoides and mast cell tumors n-3 PUFA's can decrease the inflammation
associated with these neoplasias. Omega-3 PUFA supplementation also helps to
decrease the anorexia and subsequent cachexia commonly associated with neoplastic
processes 4. Omega-3 PUFA's reduce Interleukan 1
and rumor necrosis factor both of which help to trigger cachexia normally associated
with neoplasias and. other chronic debilitating diseases. Success of the supplement
in decreasing cachexia in the dog is hard to objectively evaluate since the
majority of these, patients will succumb to their disease over time or be euthanized.
Clinically it appears that the cases I have placed on supplementation are more
comfortable, and do maintain their body weight for a longer period of time.
When supplementing with n-3 PUFA's I normally use marine oil. The dose is based
on the amount of EPA (eicosapentaenoic acid.) in the supplement. The dose is
180mg of EPA per 10 lb. of body weight. I have noted few side effects at this
dose with the exception of an occasional gastrointestinal upset and "Fish.
Breath". One potentially severe side effect that is worried about is a
decrease in normal platelet function. This has not been seen clinically and
in an unpublished study there was no significant increase in bleeding times
or change in platelet function in dogs supplemented with high dose EPA (180mg.
10lb) for a six-month period.
References:
1 Elisa P. Epidermal Lipids, Barrier Function and Desquamation.
JID 1983; 80:44s-49s.
2 Lloyd D. Essential Fatty acids and skin disease. Journal of
Small Animal Practice 1989; 30:207-212,
3 Logas D and Kunkle G. Double-blinded Crossover Study with Marine Oil Supplementation Containing High-dose Eicosapentaenoic Acid for the Treatment On Canine Pruritic Skin Disease. Vet Dermatol 1994: 5:99-104.
4 Endres S et al. The Effects of Dietary Supplementation with
nl-3 Polyunsaturated Fatty Acids on the Synthesis of Interleukin-l and Tumor
Necrosis Factor by Mononuclear Cells. The New England Journal of Medicine 1989;
320:265-271.
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