Chiara Noli, Mario Galzerano, Stefano Toma. From SUMMA Pets, n.9-2009, 21-27
Summary by the scientific editors NBF-Lanes
The hypothesis of the authors is that if the higher omega-6 and omega-3 PUFAs are administered before the inflammatory response it triggers, then anti-inflammatory or less inflammatory eicosanoids are produced with lower anti-inflammatory power of those that would be produced without the supplementation.
THE AIM OF THIS STUDY IS THE EVALUATION OF THE ORAL SUPPLEMENTATION OF BLACK CURRANT OIL (BSO) (100 MG / KG / DAY), PLACEBO-CONTROLLED, FOR THE PREVENTION OF RECURRENCE OF THE SYMPTOMS OF ATOPIC SEASONAL DERMATITIS IN DOGS.
IN THE 7 TREATED ANIMALS ITCHING AND LESIONS WERE LOWER THAN THE PREVIOUS YEAR IN ALL SUBJECTS, WHILE IN THE CONTROL GROUP LESIONS WERE LOWER THAN IN PREVIOUS YEARS ONLY IN 3/7 DOGS
PREMISE
Atopic dermatitis is an allergic disease, chronic itchy skin, with a genetic predisposition and typical clinical signs.
Up to 75% of affected dogs have, initially, seasonal clinical signs, usually in the warm months.
The current options of symptomatic therapy are involving anti-itching and anti-inflammatory steroids, cyclosporine, topical therapies and oral administration of polyunsaturated fatty acids (PUFAs).
The PUFAs after 6/8 weeks of oral administration are integrated in the cell membrane. The PUFAs that are part of the omega 6 and omega 3 groups act through modulation of anti-inflammatory eicosanoids, activation of immune cells, secretion of cytokines, the correction of defects of the lipid component of the epidermis, the stabilization of cell membranes and as Consequently, the reduction of arachidonic acid.
The blackcurrant seed oil (BSO) has received special attention as a source of PUFAs in humans and in dogs with atopic dermatitis.
BSO has a ratio Omega 6: Omega 3 to 4: 1, similar to the relationship (between 10:1 5:1) recommended for best results in reducing the activation of neutrophils and of the leukotriene LTB4, (Vaughn et al, 1994 ); BSO is particularly rich in gamma linolenic acid (GLA) and stearidonic acid (SA) and in humans is preferred in the treatment of cutaneous inflammatory diseases because the skin, being deficient of the enzyme delta 6 and delta 5 desaturase, is unable to bio-transform the essential fatty acids in a higher PUFAs, such as GLA and stearidonic acid. In the dog, until 1992 there were no specific studies.
THE STUDY
The hypothesis of the authors is that if the upper omega 6 and omega 3 PUFAs are administered and go to form a good part of the cell membrane fatty acids before the inflammatory response starts, then the eicosanoids produced have anti-inflammatory or minor inflammatory power of those that would be produced without supplementation.
MATERIALS AND METHODS
Fourteen dogs were included in the clinical field trial with a presentation of atopic season dermatitis for at least two consecutive years. All dogs had met the Willemse criteria for atopic dermatitis. During the first visit, the itching was assessed using a visual analogue scale (VAS) while injuries through CADESI.
In the second year, one or two months before the season starts, all the dogs were contacted and reassessed. On day 0 a strict flea control is started and the dogs were randomly assigned to group A (supplementation of blackcurrant seed oil daily dose to 100 mg / kg) or group B (placebo, sucrose syrup).
The treatments were administered up to 120 days. The dogs were re-evaluated by visual analogue scale and CADESI after 60, 90 and 120 days.
Supplementation with blackcurrant seed oil (100mg / kg / day – 7 dogs) or placebo (7 dogs) began two months before the expected period of the manifestation of symptoms.
The diet was not changed in the 12 months prior to the start of supplementation and remained unchanged for the entire duration of the study, being all owned animals.
RESULTS
The study results have shown that in 3/7 dogs treated the itching did not appear at all or very light, in 3/7 decreased, and only in one subject remained unchanged. In the control group the itch has not appeared in 2/7 cases, decreased in 1 subject and unchanged in 4/7 dogs.
LESIONS
In all animals that received supplementation with blackcurrant seed oil the CADESI scores decreased, and in 5/7 dogs symptoms was less than 50% over the previous year. In the control group the lesions were reduced only in 3/7 dogs.
The development of the itching and the CADESI scores were decreased in the treatment group compared with placebo or compared to the previous summer.
The results of this preliminary study show a partial / total success rate in 70% of animals.
DISCUSSION
As a source of PUFAs, BSO is very rich in GLA (16%). This higher fatty acid is rapidly converted to Diomo gamma linolenic acid (DGLA) precursor of prostaglandin E1 (PGE1) and acid 15 hydroxy eicosatrienoic (15 HETRE). These molecules have anti-inflammatory effects: among other things the ability to inhibit the release of arachidonic acid (AA) from cell membranes (Ziboh et al, 2001; Zillerberg MD et al, 2001)
- The PGE1, in laboratory animal studies, have been able to prevent and stop, acute and chronic inflammation induced by pro-inflammatory prostaglandins and bleomycin, as well as to stop the vasculitis caused by immune complexes.
- 15 HETRE was able to inhibit the production of leukotrienes highly pro-inflammatory LTB4 in in vitro models and in vivo human psoriasis (Ziboh VA, 2001)
- GLA is derived from essential fatty linoleic (LA) through the action of delta 6 desaturase: in the skin of man this enzyme is hardly present, for this reason it is preferable for extra GLA directly with the diet. The GLA is used in human medicine as it is in many fields: in dermatology a randomized controlled trial showed that early administration of GLA in children at high risk of atopic dermatitis is able to decrease the severity of symptoms during the course of the disease (CJ Van Gool, 2003).
- BSO is also particularly rich in Omega 3 fatty acids such as a-linolenic acid and stearidonic acid, eicosapentaenoic acid precursors (EPA), long-chain PUFA.
- Omega-3 long-chain PUFA are able to compete with arachidonic acid (AA) for the enzymes lipoxygenase and cyclooxygenase, favoring a decrease of the production of pro-inflammatory leukotrienes and prostaglandins (Nesbitt GH, LS Freeman, 2003) and a consequent reduction the itching. Furthermore, a high integration with Omega 3 fatty acids reduces the hepatic production of AA, thanks to the competition for the enzyme delta 5 desaturase (Zhou L, Nilsson A, 2001).
The results of this study, the first – according to the knowledge of the authors, to have investigated the preventive effect of PUFAs in general and the BSO in particular in cases of atopic seasonal dermatitis in dogs, can confirm a partial / total success on 70 % of the animals, the hypothesis at the basis of this research.
The hypothesis is: if the supplementation takes place at least 8 weeks before the RSV season, the PUFAs long chain (20 carbon atoms) such as EPA and DGLA are incorporated into the 2 position of membrane phospholipids instead of AA. Following an inflammatory stimulus, the enzyme phospholipase A2 should therefore not free AA for the production of pro-inflammatory eicosanoids but, on the contrary, DGLA and EPA, are capable of producing neutral or anti-inflammatory eicosanoids.
CONCLUSION
In conclusion, the integration with BSO at a dose of 100 mg / kg / day for OS may be of help to delay, decrease or inhibit the clinical signs of atopic seasonal dermatitis, if the oil is administered at least two months before the start the RSV season.
