Ερευνες

Abstract

The aim of this trial was to evaluate the clinical effect of VetoSkin® supplementation in dogs with atopic dermatitis fed the same diet. The control group consisted of 10 dogs selected to meet the same criteria as the trial group. All patients were given one capsule of Veto Skin® per 10 kg body weight. Clinical examination was made on the day 0, 30, 60 and 90. The CADESI 03 and PVAS (Pruritus Visual Ana log Scale) scoring systems were used to evaluate the results during the three month trial.

Key words

atopic dermatitis, atopy, essential fatty acid supplementation, eicosapentaenoic acid, gamma-linolenic acid

Essential unsaturated fatty acids (n3 and n6) have been widely used in the treatment of atopic dermatitis for more than 25 years. Their clinical significance has so far been proved in about twenty studies (1-3). Currently, essential unsaturated fatty acids are widely used in the treatment of atopic dermatitis in dogs (7, 9). They inhibit the synthesis of LBT4 by re-balancing the hydrolipid barrier on the whole surface of the dog’s skin. Polyunsaturated fatty acids are components of cell membranes; their oxidation contributes to the formation of prostaglandins and leukotrienes, two eicosanoids which take part in the development of inflamatory conditions. Both the eicosapentaenoic and gamma-linolenic acids (omega-3 and omega-6 respectively) participate in the metabolism of arachidonic acid by competing with the same enzymes, and thus reduce the production of inflamatory eicosanoids (e.g. PGE2, PGI1, LTB4). This, in turn, favors the production of anti-inflamatory eicosanoids such as PGE1, PGE3 or LT5. Eicosapentaenoic acid can be found in oil obtained from some fish and the highest concentration of gamma-linolenic acidis in oils from evening primrose and borage (4, 5, 7). Preparations containing essential unsaturated fatty acids combined with other substances such as vitamins, minerals or cofactors have been a relatively new area and further experiments are needed to evaluate their effectiveness (7, 8). Many producers believe that the right combination of a few substances will maximize their efficiency (7). So far, however, there are no studies concerning those types of products. No studies which would confirm that efficiency have yet been presented. In one study involving a double-blind trial the product containing polyunsaturated fatty acids and cofactors proved less effective than a product without cofactors (10). However, further research is needed. The analyzed Vetoskin preparation contains omega-3 and omega-6 acids as well as B vitamins, biotin and zinc. B vitamins are constantly synthesized by the intestinal flora but as they are water soluble, they are not stored in the body. Therefore, they have to be continuously supplied. Deficiency in group-B vitamins may lead to skin conditions. Such conditions, however, are not very specific and other diseases should be taken into consideration in the process of differential diagnosis. Clinical symptoms of a B-group vitamin deficiency include dull hair, dry seborrhea and hair loss on some facial areas. Vitamin B (pyridoxine) takes part in the metabolism of many nutrients relating to the normal functioning of hair and skin such as the transformation of linoleic acid into arachidonic acid, methionine into cysteine and tryptophan into niacin (vit. PP). It also participates in the synthesis of picolinic acid, crucial for zinc to penetrate the intestinal mucosa (7, 8). Zinc is an integral part of many metalloenzymes which participate in regulating the metabolism. It is an important cofactor for the RNA and DNA polymerases and particularly important for fast dividing cells such as those of the epidermis. Zinc is essential for the biosynthesis of fatty acids and takes part in the metabolism of vitamin A. Zinc plays a crucial role in ensuring the normal functions of the immune system and is also present inflamatory reactions. The dermatological symptoms of zinc deficiency include: slow healing of wounds, local erythema, patches of hair loss, crust and desquamation. The above-mentioned lesions usually occur in places prone to injuries, such as skin-membrane connections, distal parts of the body and fingertips. Fur becomes dull and bacterial and fungal infections occur. However, diet-related zinc deficiency is infrequent (7). Biotin (vitamins H and B7) is a co-enzyme of a few various enzymes. It is an essential component of biotin dependent carboxylases. Carboxylases are enzymes which are vital for many important biochemical reactions, for example in the process of the formation of glucose (gluconeogenesis), the synthesis of fatty acids or the cycle of citric acid. Biotin supports the normal functions of the thyroid gland and contributes to the normal functioning of the skin and hair. Symptoms of biotin deficiency include dermatitis, urticaria and hair loss. Other systemic manifestations may include an elevated level of cholesterol and inflamatory lesions in the bowels. As biotin can be synthesized by the intestinal flora, its deficiency occurs very rarely and is usually caused by other than nutritional factors. Biotin deficiency happens during a prolonged antibiotic therapy which is often prescribed in the treatment of post-atopic dermatitis bacterial infections (phlegmon) (1, 7, 9).

Material and methods

The study was carried out on 20 dogs as the study group (group I) and 10 dogs as the control group (group II). All dogs had atopic dermatitis. The diagnosis of atopic dermatitis in the animals from both groups was made based on the diagnostic criteria of Claude Favrot (12, 13) and intradermic tests (Agroskin RTU 20; Agrolabo). Additionally, before carrying out the intradermic test, all dogs were subject to rapid diagnostic tests to assess the total number of IgE antibodies (VetExpert). The tests gave positive results in all cases. The intradermic tests were conducted at least 3 months before the animals were qualified for the study. All the dogs were found sensitive to many all-year allergens. The dogs with seasonal allergies were not included in the study. In all dogs from both groups the symptoms of atopic dermatitis of varied intensity had been present for the whole year. The study group consisted of dogs aged 2-6 years (the average of 4.2 years), 10 females, including 4 spayed, and 10 males, including 5 castrated ones. The dogs represented different breeds (5 Labradors, 5 mongrels, 3 West-Highland White Terriers, 3 Beagles, 3 German Shepherds and 1 Dachshund) and their body weight ranged from 10 to 30 kg. The control group consisted of 10 dogs aged 3-6 (the average of 5 years), 5 females, including 4 spayed ones and 5 males, including 3 castrated ones. The dogs represented different breeds, 2 Labradors, 3 mongrels, 2 West-highland white terriers and 3 German shepherds of body weight ranging from 10 to 40 kg. Food allergies were excluded in all dogs by using hydrolyzed elimination diet for at least 12 weeks. Throughout the study all dogs from both the study and the control groups followed the same diet (Hypoalergenic® RoyalCanin). The dogs did not undergo allergen immunotherapies. During the three-month study the dogs did not receive anti-inflamatory drugs, glucocorticoids, antibiotics, antihistamines or cyclosporine. The animals from the study group received VetoSkin® containing B-group vitamins (B1, B2, B6 and B12), NNKT-Omega-3/Omega-6, biotin and zinc. The product was administered to the dogs by their owners at home for 12 successive weeks (90 days/3 months) in March, April and May. The dosage of the product was determined based on the anima l’s body weight and was as follows: 1 capsule of VetoSkin® for every 10 kg of body weight. The capsules could be administered in whole or, as they are twist-off type, it was also possible to only give the con tent. The dogs from the control group did not receive VetoSkin®. All dogs underwent dermatological examinations four times on the following days: 0, 30th, 60th and 90th. The intensification of lesions was assessed by using the CADESI 03 sys tem. The levels of erythema, lichen, skin abrasion and hair loss caused by self-mutilation in 62 areas of the body were analyzed. The following point-scale was used to assess the lesions: 0 – no lesions, 1 – mild lesions, 2, 3 – moderate lesions and 4, 5 – considerable lesions. All dogs were in remission from the disease and mild to moderate intensity of the symptoms of atopic dermatitis was observed. On the 0 day the dogs scored up to 84 points in the CADESI system. Additionally, the intensity of pruritus in the PVAS (Pruritus Visual Analog Scale) 5-stage scale was measured. The criteria defining pruritus used in the study were according to Marselli et al.: 0 points – no pruritus, 1 point – mild pruritus, the animal scratches itself for less than 10% of the observation time, 2 points – mild to moderate pruritus, 30% of time spent on scratching, 3 points – moderate pruritus, 30-50% of time spent on scratching, 4 – moderate to considerable, 50-75% of time, including at night and 5 – considerable pruritus when the animal scratches itself for more than 75% of time, including at night and while eating. The assessment was done by the owners on the following days of the study: 0, 30th, 60th and 90th and the results were marked on the scale of pruritus intensity.

Statistical analysis

The quantitative variable was presented as an average standard deviation. Additionally, a 95% confdence interval (95% CI) was calculated for average group means. The statistical analysis was conducted using a two-way repeated me asures analysis of variance (group as the random factor and time as the non-random factor). As sphericity was assumed (the Mauchley test p = 0.206), one-dimensional tests were used. The Tukey’s test was used for uneven group numbers in the post-hoc analysis. The result was considered statistically signifcant when the two-tailed p value was less than 0.05. The statistical analysis was carried out by Michał Czopowicz, D.V.M. PhD, from the Laboratory of Veterinary Epidemiology and Economics of the Department of Veterinary Medicine of the Warsaw University of Life Sciences in Warsaw, Poland. Statistically signifcant differences were observed for inter-group comparison (p < 0.001), inter-time points comparison (p < 0.001) and for the interaction of gro up and time (p < 0.001). The value of the measured parameter changed over time in both groups and the direction of those changes was divergent. In the study group the CADESI value remained the same between day 0 and 30 (p = 0.248) but was statistically signifcantly lower between the 30th and 60th days (p < 0.001) and remained constant between the 60th and 90th days (p = 0.998). Statistically signifcant decrease in the CADESI value happened between the 30th and 60th days. In the control group the CADESI value systematically increased and on the 60th day was statistically signifcantly higher (p = 0.016) compared with day 0, and on the 90th day it was statistically signifcantly higher than on days 0, 30 and even on the 60th day (p < 0.001). The CADESI value was different between the groups. A statistically signifcant difference between the study and control groups occurred on the 60th (p < 0.001) and 90th days (p < 0.001). There was no statistically signifcant difference between the groups on days 0 (p = 0.994) and 30 (p = 0.999). It is good because it means that the groups were comparable at the very beginning of the study.

Results of the study and discussion

At the beginning of the study in dogs from both the study and control groups mild to moderate symptoms of atopic dermatitis were observed. On day 0 the CADESI value in group I ranged from 53 to 84 points (the average of 62) and in group II it was from 49 to 79 points (the average of 65). On the 30th day the CADESI value in group I was from 63 to 83 points (average 70) and in group II – from 49 to 90 (average 75). On the 60th day of the study the CADESI value for group I ranged from 34 to 50 points (average 42) and in group II – from 32 to 130 (average 80). On the 90th day of the study the CADESI value for group I was from 21 to 49 points (ave rage 39) and in group II – from 42 to 120 (average 100).

The intensity of pruritus according to PVAS (Pruritus Visual Analog Scale) was also assessed four times. On day 0 in 9 dogs from the study group (45%) mild pruritus was observed, in 8 dogs (40%) it ranged from mild to moderate and was moderate in 3 dogs (15%). On day 0 mild pruritus was observed in 4 dogs (40%), mild to moderate – in 3 dogs (30%) and moderate – in 3 dogs (30%). On the 30th day of the study in 7 dogs from group I (35%) mild pruritus was observed, in 9 dogs (45%) it ranged from mild to moderate and it was moderate in 4 dogs (20%). In group II mild to moderate pruritus was reported in 7 dogs (70%) and in the case of 3 dogs (30%) it was moderate. On the 60th day in 10 dogs from the study group (50%) a mild intensity of pruritus was observed, mild to moderate in 9 dogs (45%) and mode rate in 1 case (5%). In the control group the intensity of pruritus was mild to moderate in 5 dogs (50%), moderate in 2 dogs (20%) and moderate to considerable in 3 dogs (30%). On the 90th day of the study in 12 dogs from the study group (60%) the intensity of pruritus was mild and it ranged from mild to moderate in the remaining 8 dogs (40%). On the same day in the control group moderate pruritus was reported in 4 dogs (40%) and in 6 dogs (60%) it ranged from moderate to considerable. The results of the study indicate that after 2 months of constant administration of the VetoSkin® preparation the clinical condition of dogs with atopic dermatitis im proved and remained stable for the following 4 weeks. In the control group, where the preparation was not ad ministered, the clinical condition worsened with time. Similar results were obtained in studies conducted earlier (1, 2, 5, 7). In one of the studies it was observed that in young dogs with recently developed atopic dermatitis the response of the body was significantly better after two months. In this study the improvement was observed in both younger (2/3 years) and older (5 years) dogs (2-4). In the study concerning the intensity of pruritus according to PVAS (Pruritus Visual Analog Scale) a considerable reduction in the intensity of pruritus was observed in the study group after 60 and 90 days. In the dogs from the control group the intensity of pruritus increased gradually with time and was followed by complications such as phlegmon which after the study had finished required a treatment with glucocorticoids and antibiotics. In none of the dogs from the study group the side effects mentioned in the available literature and including diarrhea and pancreatitis were noticed (7). The results obtained from the study indicate that VetoSkin® containing polyunsaturated fatty acids, B-group vitamins, zinc and biotin may be used in dogs with atopic dermatitis to alleviate the dermatological symptoms and the intensity of pruritus.

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