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Veteritrury D~rmrrrolo~y , Vol. 4. No. 4, pp. 191-197. 1993 Copyright .''', 1994 ESVD and ACVD

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The Effects of Essential Fatty Acid Supplementation on Intradermal Test Reactivity in Atopic Dogs:

a Preliminary Study ROSS BOND.* DAVID H. LLOYD & J. MARK CRAIG

Department of Small Animal Medicine and Surgery, The Royal Veterinary College, University of London, Hawkshead Campus, North Mymms, Hatfield, Herts AL9 7TA, U.K.

(Received 28 October 1993; uccepted I1 Junuury 1994)

Abstract-Twenty-one perennially affected atopic dogs with previous intradermal test reactivity to two or more environmental allergens were retested while receiving either a combination of evening primrose oil and fish oil (EfaVet Regular, Efamol Vet) or a concentrated supplement containing gammalinolenic acid and eicosapentaenoic acid ( H G F capsules). Significant differences in the mean number of positive reactions before and during therapy were not found. In addition, the mean histamine, Dermatophagoides pteronyssinus and housedust wheal diameters before and during therapy were not significantly different. However, the mean human dander wheal diameter was significantly reduced (P < 0.05) at the second test, and the mean Dermatuphuguides favinue wheal diameter was significantly reduced (P < 0.05) in a group of seven dogs which had received long-term essential fatty acid supplementation with H G F capsules. These results indicate that essential fatty acid supplementation does not abrogate but may reduce intradermal test reactivity in atopic dogs.

Key Words: Canine atopy; Essential fatty acids; Intradermal tests; Gammalinolenic acid; Eicosapeiitaenoic acid.

INTRODUCTION

Intradermal testing is widely used in the diagnosis of canine atopy and flea allergy dermatitis. Positive intradermal test reactivity which correlates with the clinical history supports a diagnosis of canine atopy in dogs with other historical and clinical features of this disease ( 1 , 2 ) . A knowledge of the specific sensi- tivities of an atopic dog allows the clinician to advise the owner on the possibility of allergen avoidance measures and to prepare specific immunotherapy (hyposensitization) courses (3 , 4).

Recent therapy with topical or systemic glucocor- ticoids and antihistamines routinely used in the treat- ment of allergic skin disease may inhibit intradermal test reactivity in dogs for periods ranging from days to several months, and guidelines for the withdrawal of these medications prior to intradermal testing have been suggested ( 3 , 5). Although essential fatty acid (EFA) supplementation is now widely used in the management of canine atopy, to the authors'

*Author to whom all correspondence should be addressed. Study supported by Efamol Vet, Guildford, U.K.

knowledge the effects of these products on intrader- ma1 testing have not been reported.

The purpose of this study was to determine whether dietary supplementation with essential fatty acids would suppress the skin reactivity to intra- dermal allergens in a group of atopic dogs which had previously shown positive reactions.

MATERIALS AND METHODS

Thirteen male and eight female perennially affected atopic dogs of various breeds, aged between 1 and 8 years (mean 4.1), were studied (Table 1). The diag- nosis of canine atopy was based on a consideration of historical and clinical findings, exclusion of other pruritic dermatoses, fulfilment of the diagnostic criteria proposed by Willemse (2), and positive intra- dermal test reactivity to two or more environmental allergens correlating with the clinical history. Four of the dogs also had positive immediate intradermal test reactivity to the flea allergen, suggesting concur- rent flea hypersensitivity.

The intradermal tests were performed using a stan- dard panel of 48 aqueous allergens (Greer Labor- atories, Lenoir, U.S.A.; ARTU Biologicals NV,

191

192 Ross Bond et al.

TABLE 1 . Clinical details and results of intradermal testing in 21 atopic dogs before and during essential fatty acid supplementation

Age# Interval Duration Daily GLA Daily EPA Positive Positive

Number Breed years Sex in weeks in weeks* (mg.kg-') (mg.kg-') test one test two in between tests of therapy dose dose reactions at reactions at

Ecening primrose undjish oil comhination (Group A ) I English setter 3 F 12 2 German shepherd 6 FN 10 3 Cross 5 M 16 4 Irish setter 7 F N 13 5 Golden retriever 2 M 18 6 Labrador retriever 3 FN 9 7 Cross 3 M 8

Conr,entiated./ut/y ucid supplement (Group B) 8 German WHP 6 M 13 9 Labrador retriever 2 F 26

10 Cross 2 M 7 1 1 English pointer 3 M N 18 12 Labrador retriever 5 F 9 13 Boxer 1 F 1 1 14 Labrador retriever 4 F 9

Concentrated fu t ty mid supplemenr (Group C ) I S Boxer 4 M 88 16 Golden retriever 4 M 103 17 Golden retriever 3 M 74 18 Labroador retriever 5 M 74 19 Labroador retriever 8 M 60 20 Labrador cross 6 M 50 21 Labrador cross 4 M 118

12 10 16 13 18 9 8

13 26 I

18 9

1 1 9

43 (48) 43 (60) 52 (22) 22 (45) 26 (34) 40 (10) 40 (78)

18.9 13.8 12.4 19.6 19.6 16.5 11.3

17.1 29.7 23.2 19.3 17.1 19.9 19.9

22.4 24.1 21.6 21.2 22.7 18.8 15.4

9.5 6.9 6.2 9.9 9.9 8.3 5.1

3.0 5.3 4.1 3.5 3.1 3.5 3.5

4.0 4.3 3.8 4.9 4.0 3.4 2.7

8 8

11 5 61 6 4

*Figures in parentheses denote duration of previous therapy with evening primrose oil and fish oil combination 'IHuman dander not available at second test. $Age at time of second intrddermal test. WHP. Wirehaired pointer; F, female; M, male; N, neutered; GLA, gammalinolenic acid; EPA, eicosapentaenoic acid.

Lelystead, Netherlands) routinely used for diagnostic purposes at the Royal Veterinary College (Table 2). The Greer allergens were purchased as concentrated

solutions and fresh testing-strength dilutions (Table 2) were prepared at intervals of 4-6 weeks. The ARTU allergens were supplied freeze-dried; fresh

TABLE 2. Concentrations of allergenic extracts used in the study

I . Ctenocephnlides spp.*

fndoor uliergms 2. t Tyrophugus putresecuniiae$ 3. tAcaru,s .sire$ 4. l3ermutophugoirles pteronyssinuss 5. Drimutophu@des fiirinue6 6. Housedust 11 7. Cat dander 8. tHuman dander' 9. Sheep epithelia**

10. Mixed feathers 11 . Kapok

Tree pollens 34. Birch 35. Alder 36. Hazel 37. Beech 38. Ash 39. Sycamore 40. Poplar 41. Oak 42. Willow

Weed pollens 12. Mugwort 13. Rape 14. Jerusalen Oak 15. Lamb's Quarter 16. Daisy 17. Plantain 18. Sheep's Sorrel 19. Yellow Dock 20. Dandelion 21. Clover 22. Nettle

Grass pollens 43. Meadow grass 44. Fescue 45. Cocksfoot 46. Bent-grass 47. Italian rye grass 48. Timothy

Moulds 23. Afternuria ulternatu 24. Aspergillus futnigurus 25. Boirytis cinerar 26. Ciudosporium herbarum 27. Epicoccum purpurascens 28. Fu.rarium moniliforme 29. Helminihosporium satiuum 30. Penicilhum notatum 31. Phoma betae 32. Pullularia pullulans 33. Rhodoiorulu rubra

Testing strength for allergens: 1000 protein nitrogen units (PNU).ml-' unless indicated. *1:1000 w/v; ?Allergen supplied by ARTU; $10 Noon uni t sm- ' ; #1:2000 w/v; 11250 PNU/ml; 110 pg ml-'; **500 PNU.ml-l

EFAs and intradermal test reactivity 193

testing-strength solutions were prepared every 4 months in accordance with the manufacturer's in- structions. All allergens were stored in glass bottles at 4 T . A 1 : 100,000 dilution of histamine phosphate (Greer Laboratories) and the saline diluent contain- ing 0.4% phenol (Greer Laboratories) were used as positive and negative controls, respectively.

The dogs were sedated using xylazine (Rompun, Bayer U.K. Ltd, Bury St Edmunds, U.K.), ad- ministered by intramuscular injection at a dose of 0.5-0.6 mg.kg-', and restrained in right lateral re- cumbency. The hair was removed from a rectangular area measuring approximately 18 x 12 cm on the left lateral thorax using electric clippers (Oster, McMinnville, U.S.A.) with a No. 40 blade. Five rows of 10 injection sites were marked at intervals of approximately 1.5 cm using a marker pen. A volume of 0.05 ml of each of the test solutions and controls was injected intradermally at the appropriate site using 1 ml syringes and 25 gauge needles (Monoject, St. Louis, MO, U.S.A.). Systemic glucocorticoids had been withdrawn for at least 6 weeks prior to intrader- ma1 testing on each occasion, and antihistamines, nonsteroidal anti-inflammatory agents and topical glucocorticoids had been withdrawn for at least 10 days. None of the dogs studies received immuno- therapy (hyposensitization) between the two intra- dermal tests.

The reactions were objectively assessed by measur- ing the horizontal and vertical dimensions of any wheals or fluid blebs with a ruler 15 min after injec- tion; the wheal diameter was calculated as the mean of these two measurements. Tests were interpreted only if a wheal with a diameter of 10 mm or more was present at the positive control site, and no reaction other than a small fluid bleb was evident at the negative control site. A positive reaction was defined as a wheal of diameter greater than or equal to the midpoint of the diameters of the positive and negative controls. Because several veterinarians per- formed the intradermal tests, subjective assessments of the reactions were not used.

The intradermal tests were repeated during treat- ment with one of two essential fatty acid supple- ments and the results compared to those obtained at the first test. Seven dogs (Group A, Table I ) were given a combination of evening primrose oil and fish oil (EfaVet Regular 500 mg capsules, Efamol Vet, Guildford, U.K.) for between 8 and 18 weeks (mean 12); the mean doses of gammalinolenic acid (GLA) and eicosapentaenoic acid (EPA) at the time of the second intradermal test were 16.0 and 8.1 mg.kgg', respectively. Seven dogs (Group B) received a con- centrated essential fatty acid supplement (HGF cap- sules, Efamol Vet) containing 280 mg gamma- linolenic acid and 50 mg eicosapentaenoic acid for 7 to 26 weeks (mean 13); the mean doses of GLA and EPA at the time of the second intradermal test were 20.9 and 3.7 mg.kgg', respectively (Table 1). The second intradermal test was routinely performed

once the clinical signs of the allergic disease had reduced such that both the owner and investigator agreed that no therapy other than the essential fatty acids, shampoos and routine parasiticidal treatments was required. However, in three dogs which showed a poor response to essential fatty acids, the second test was performed prior to the administration of alternative anti-inflammatory drugs.

In order to determine the effects of long-term essential fatty acid supplementation on intradermal test reactivity, a further seven dogs (Group C , Table 1) were retested following 50-118 weeks (mean 81, Table 1) of EFA supplementation. These dogs had been previously given the evening primrose and fish oil combination for periods ranging from 10 to 78 weeks (mean 43), followed by 22-52 weeks (mean 38) of therapy with the concentrated product; the mean doses of GLA and EPA at the time of the second intradermal test were 21.7 and 3.9 mg.kg-', respectively. All these dogs were well-controlled at the second test.

The number of positive reactions and the wheal diameters recorded at the histamine, housedust, housedust mites (Dermutophugoides pferonyssinus, f). furinae) and human dander injection sites within each group before and during essential fatty acid supplementation were compared using Wilcoxon's signed rank test.

RESULTS

All dogs studied developed a wheal and flare reac- tion following the intradermal injection of histamine (positive control), both before and during treatment with the essential fatty acid supplements. Differences in the mean histamine wheal diameter at the first and second tests for each group, and for all groups combined, were not statistically significant (Table 3).

All the dogs in the three treatment groups showed positive intradermal test reactivity to two or more allergens when retested while receiving the essential fatty acid supplements (Table I) . In Group A, all but two of the dogs (numbers 1 and 2) were judged to be well-controlled at the time of the second test. The number of positive reactions at the second test in this group was reduced in four cases (numbers 1, 3, 5 and 6) when compared to the initial test results. Three dogs (numbers 2, 4 and 7) showed the same number of positive reactions at each test; however, in only two cases (dogs 2 and 4) were the results of both the first and second tests identical. The mean numbers of positive reactions at the first and second tests (5.9 and 4.1, respectively) were not significantly different. Thirteen out of 41 reactions positive at the first test were negative at the second, and one out of 29 reactions positive at the second test had been previously negative (Table 4). The repeatability of the intradermal test results in Group A, calculated as the percentage of the number of reactions positive at

194 Ross Bond et al.

TABLE 3. Wheal diameters (mean k SE) in mm 15 min following the intraderma1 injction of histamine (positive control), housedust mites, housedust and human dander allergens before (test 1) and during (test 2) essential fatty acid supplementation

Group Histamine D. ptrronyssinus D. furinue Housedust Human dander Test 1 Test 2 Test I Test 2 Test 1 Test 2 Test 1 Test 2 Test 1 Test 2

A 12.3f0.3 11.4kO.5 9 .6kl .O 9 .7f0 .4 11.4k0.5 11.6k0.4 10.1kO.3 10.0+0.3 9 .9k0 .9 7.1k1.0 B 11 .7k0 .9 12.0f0.5 9 .6k1 .2 12.0+0.9 12.0+0.8 12.7k1.0 10.7f0.8 12.1+0.9 9 .0k1 .4 t 9.1k0.9t C 13 .3 i0 .7 12.3k0.5 10.9k1.2 9.4k1.1 12.7kO.b 10.l&1.1* 10.6+1.1 10 .9 t0 .6 8 . 9 i 0 . 7 7.9k1.0 All 12 .4 i0 .4 11 .9 i0 .3 10.0f0.7 10.4+0.5 12.0T0.4 11.5k0.5 10.5&0.5 11.0+0.4 9 .1 i0 .6 7.9f.0.6'

Comparison with test I , * P < 0.05 (Wilcoxon's signed rank test); t N = 6 (human dander not available at second test).

TABLE 4. Results of intradermal tests before (test 1) and during (test 2) essential fatty acid supplementation in each group of dogs

Treatment Positive both Negative both Positive test 1 Negative test 1 group Allergen/control tests tests Negative test 2 positive test 2

B

C

All

A Histamine Flea Indoor allergens Tree pollens Grass pollens Weed pollens Moulds

Histamine Flea Indoor allergens* Tree pollens Grass pollens Weed pollens Moulds

Histamine Flea Indoor allergens Tree pollens Grass pollens Weed pollens Moulds

Histamine Flea Indoor allergens Tree pollens Grass pollens Weed pollens Moulds

7 1

24 0 1 2 0

7 2

31 0 1 0 0

7 0

22 0 1 3 0

21 3

77 0 3 5 0

0 6

42 59 38 73 76

0 5

22 61 40 76 76

0 6

29 62 37 67 77

0 17 93

182 115 216 229

0 0 3 4 3 2 1

0 0 5 0 1 0 0

0 1 7 0 4 6 0

0 1

15 4 8 8 1

0 0 1 0 0 0 0

0 0

10 2 0 1 1

0 0

12 1 0 1 0

0 0

23 3 0 2 1

*One allergen positive at the first test not available at the second test in two cases

both the first and second tests out of the total number of positive reactions at both tests, was 80.0 per cent.

None of the dogs in Groups B and C had identical results at the first and second tests. All but one of these dogs (number 9, Group B) were well-controlled when re-tested. In Group B, the number of positive reactions per dog was unchanged in three cases (numbers 8, 10 and 14), reduced in one case (number 12), and increased in three cases (numbers 9, 1 I and 13), when compared to the previous results. The mean numbers of positive reactions at the first and second tests (6.0 and 6.9, respectively) were not significantly different. Six out of 42 reactions positive at the first test were negative at the second, and 14 out of 46 reactions positive at the second test had

been previously negative. The repeatability of the test results in this group was 77.3 per cent.

Three dogs in Group C (numbers 17, 20 and 21) had more positive reactions at the second test, whereas the number of positive reactions was un- changed in two cases (numbers 5 and 16) and re- duced in three cases (numbers 18 and 19). The mean numbers of positive reactions at the initial and sec- ond tests (6.3 and 5.7, respectively) were not signifi- cantly different. Eighteen out of 44 reactions positive at the first test were negative at the second, and 14 out of 40 reactions positive at the second test had been negative at the first. The repeatability of the test results in Group C was 61.9 per cent. For all dogs studied, the mean number of positive reactions dur- ing EFA therapy (5.6) was lower than that prior to

EFAs and intradermal test reactivity 195

supplementation (6.0); however, the difference was not significant. The repeatability of the intradermal test results in all dogs studied was 72.7 per cent.

Reactions to D. pteronyssinus, D. farinae, house- dust and human dander accounted for 133 out of a total of 244 positive test results. In groups A and B, differences between the mean wheal diameters for each of these four allergens before and during essen- tial fatty acid supplementation were not significant (Table 3). In group C, the mean D. farinae wheal diameter at the second test (10.1 mm) was signifi- cantly reduced (P < 0.05) when compared to the first test (12.7mm); all seven dogs in this group reacted positively to this allergen at the first test, whereas two were negative at the second. Significant differ- ences between the paired D. pteronyssinus, housedust and human dander mean wheal diameters were not found. Comparison of the overall mean wheal di- ameters for all three groups combined showed that, of the four allergens assessed, only the human dan- der wheal diameter was significantly reduced (P < 0.05) during essential fatty acid therapy (Table 3).

Of the 21 dogs, seven showed positive reactions to human dander at both tests, six were negative at both, five were positive at the first test but negative when re-tested, and two were negative at the first test but positive at the second test. One dog (number 12) which reacted positively to human dander could not be retested with this allergen because it was unavailable.

Eight of the dogs reacted to pollen allergens at either one or both tests, and pollen reactions ac- counted for 41 out of the 234 positive test results (Tables 4 and 5). In these eight dogs, the mean number of positive reactions at the first and second tests (3.5 and 1.6, respectively) was not significantly different. Three dogs reacted positively to more pol- len allergens at the second test, whereas two dogs reacted to the same number, and three dogs showed fewer reactions. Two dogs (numbers 1 and 19) had markedly fewer pollen reactions at the second test; both these dogs were retested during or shortly after the end of the pollen season. Of the four dogs which reacted positively to the flea allergen at the initial

TABLE 5 . Number of pollen reactions before (test 1) and during (test 2) essential fatty acid supplementation, and the date of each test in eight dogs which reacted to pollen allergens

Test 1 Test 2 Dog Positive Positive

number Date tested reactions Date tested reactions

1 3 8 9

10 15 18 19

May March June June December January June October

11 1 0 0 2 2 2

10

August July September January February October November November

test, three were positive at the second test and one was negative (Table 4).

DISCUSSION

The interpretation of the results of the present study is hindered by the absence of a control group con- sisting of dogs retested following a period of no treatment, and by the lack of published information on the repeatability of intradermal test reactions in dogs. Although each dog served as its own control, there are several factors other than essential fatty acid supplementation which could have influenced the test results. Batch variability and deterioration during storage may have affected the antigenic po- tency of the test solutions; however, fresh testing- strength solutions were regularly prepared in an attempt to minimize the latter. Injection technique, such as the depth of needle placement within the skin, could also affect wheal diameter in the sensi- tized patient, and host reactivity may fluctuate in response to factors such as endogenous glucocorti- coid or catecholamine release (3).

Furthermore, it is possible that certain dogs could have spontaneously gained or lost sensitivities to various allergens in the period between the tests, especially if the interval between tests was prolonged. In support of this, the repeatability of the tests was lowest in group C, which had the greatest interval between tests. Willemse (2) and others reported that 11 out of 24 atopic dogs which were retested follow- ing a course of placebo (diluent plus alum-adjuvant) immunotherapy had different results when compared to the first test. Similarly, testing dogs which have not been exposed to seasonal allergens such as pol- lens for several months could lead to false-negative results caused by reduced levels of reaginic antibody (3). However, although Nesbitt and others (7) re- ported seasonal differences in the frequency of posi- tive reactions to tree, grass and weed pollens, their study showed that many dogs were able to react to pollen allergens throughout the year, and these authors were unable to identify an optimum season for intradermal testing.

Despite these limitations, it is clear that atopic dogs receiving high doses of EFA supplements are able to develop wheal and ,flare reactions following the intradermal injection of histamine and environ- mental allergens. All but three of the dogs studied were judged to be well-controlled by EFA supple- mentation when retested, indicating that control of atopic disease by both short- and long-term EFA supplementation is not accompanied by abrogation of the immediate inflammatory responses subsequent to mast cell degranulation. Therapy did not appear to affect the numbers of positive reactions observed or wheal diameter following the intradermal injec- tion of housedust or D. pteronyssinus allergens, whereas there were significant reductions in the

196 Ross Bond e t al.

D. farinae and human dander wheal diameters a t the second tests in two of the treatment groups; the reason for this dissimilar effect is not clear. However, these findings suggest that E F A supplements should be routinely withdrawn prior to intradermal testing. In exceptional circumstances, clinicians could con- sider using E F A supplements prior to intradermally testing severely affected atopic dogs which cannot tolerate withdrawal of all medication. Scott (198 1) has reported successful immunotherapy using a max- imum of 10 allergens in dogs which reacted to u p to 28 allergens on intradermal testing, indicating that this mode of therapy can be successful even when not all potentially relevant allergens are included in the vaccine.

The high incidence of positive reactions to indoor allergens and the low incidence of positive reactions to seasonal allergens in the present study was in accordance with the results of previous European studies on intradermal testing in dogs (8, 9). Several North American surveys have consistently reported a higher incidence of in-tradermal test reactivity to pollen allergens in atopic dogs when compared to that reported in Europe (1 , 8, lo); the reasons for these differences are not clear. The low frequency of pollen reactions in the dogs studied precludes full assessment of the effects of E F A supplementation o n skin reactivity t o these allergens. I t seems unlikely that the marked reduction in pollen reactivity in dog numbers 1 and 19 was associated with the possible seasonal effects previously discussed because these dogs were retested during or shortly after the peak pollen months in the U.K.

This study indicates that EFA supplementation does not abrogate intradermal test reactivity in atopic dogs, but it may partially suppress the re- sponse of certain individuals. Further controlled studies are required t o determine the repeatability of intradermal test results in atopic dogs receiving both n o treatment and E F A supplements, and if the re- sults of this preliminary study are confirmed, t o

establish appropriate withdrawal periods for EFAs prior t o testing.

ACKNOWLEDGEMENT

The authors are grateful t o Mrs L. Steele VN for skilled technical assistance.

REFERENCES

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2.

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Scott, D. W. Observations on canine atopy. Journal of the American Animal Hospital Association 1981; 17:

Willemse, T. Atopic skin disease: a review and a reconsideration of diagnostic criteria. Journal of Small Animal Practice 1986; 27: 771-8. Reedy, L. M., Miller, W. H. Allergic skin diseases of dogs and cats. Philadelphia: W. B. Saunders, 1989: 81-109. Bevier, D. E. Long-term management of atopic disease in the dog. Veterinary Clinics of North America: Small Animal Practice 1990; 20: 1487-507. Griffin, C. E. Canine atopic disease. In: C. E. Griffin, K. W. Kwochka and J. M. MacDonald, eds. Current veterinary dermatology. St. Louis: Mosby Year Book, 1993: 99-120. Willemse, A,, Van den Brom, W. E., Rijnberk, A. Effect of hyposensitization on atopic dermatitis in dogs. Jour- nalofthe American Veterinary Medical Association 1984; 184: 1277-80. Nesbitt, G. H., Kedan, G. S., Caciolo, P. Canine atopy part 1. Etiology and diagnosis. The Compendium on Continuing Education 1984; 6: 73-84. Carlotti, D. N., Costargent, F. Analyse statistique de tests cutanes positifs chez 449 chiens atteints de der- matite allergique. Pratique medicale & chirurgicale 1992; 27: 53-69. Ferguson, E. A. A review of intradermal skin testing in the U.K. Veterinary Dermatology Newsletter 1992; 14:

DeBoer, D. J. Survey of intradermal skin testing prac- tices in North America. Journal of the American Veteri- nary Medical Association 1989; 195: 1357-63.

91 - 100.

13-8.

RCsumC-Vingt et un chiens atopiques, presentant des symptames non saisonniers, ayant eu des tests cutanes positifs a au moins un pneumallergene ont ete testes alors qu’ils recevaient une association d’huile d’onagre et d’huile de Poisson (Efa Vet Regular, Efamol Vet) ou un supplement concentre d’acides gammalinolenique et eicosapentaenoique (capsules HGF). Aucune difference significative dans le nombre moyen de reactions positives avant et apres traitement n’a tte observee. En outre les diametres moyens des reactions a l’histamine. Dermutophagoi’des pteronyssinus et la poussere de maison avant et apres traitement n’etaient pas significativement diffirents. Toutefois, le diametre moyen des reactions aux squames humaines etaient significativement reduits ( P < 0,05) lors du second test, et le diametre moyen des reactions a Dermatophagoib%sfurinae etait significativement rkduit ( P < 0,05) dans un groupe de sept chiens ayant reGu une supplementation 1 long terme de capsules HGF. Ces resultate montrent qu’une supplementation en acides gras essentiel n’anihile pas les tests cutanks mais peu moderer la rbactivite cutante chez certains chiens atopiques. [Bond, R., Lloyd, D. H., Craig, J. M. The effect of essential fatty acid supplementation on intradermal test reactivity in atopic dogs: a preliminary study (Influence d’une supplementation zi base d’acides gras essentiels sur la rCactivitC cutanee a des tests intradermiques chez le chien atopique: etude preliminaire). Veterinary Dermatology 1993; 4: 191 - 197.1

EFAs and intradermal test reactivity 197

Resumen-Veintiun perros atopicos de tip0 estacional que presentaban reactividad positiva en la prueba de inyacciones intradermicas con respecto a dos o mas alergenos ambientales, fueron sometidos a una segunda prueba recibiendo simultaneamente una combinacion de aceite de Evening Primrose y aceite de pescado (Efa Vet Regular, Efamol Vet) o un concentrado que contenia icidos gammalinoleico y ecosapentanoico (HGF capsulas). No se encontraron diferencias significativas en la media de las reacciones positivas antes y despues de la medicacion. Tampoco se encontraron diferencias significativas entre las medidas del diametro de la roncha producida por la histamina, el Dermatophugoides pteronyssinus y el alergeno del polvo. Sin embargo, la media del diametro producido por el alergeno de la caspa humana se vi6 considerablemente reducida en el segundo test (P < 0.05), asi como la del Dermatophagoides farinae ( P < 0.05) en un grupo de siete perros 10s cuales recibieron suplementacihn con acidos grasos esenciales a largo plato con HGF capsulas. Estos resultados indican que el us0 de acidos grasos esenciales no produce supresihn de las reacciones positivas del test intradermico en perros atopicos, per0 si de las mismas. [Bond, R., Lloyd, D.H., Craig, J.M. The effect of essential fatty acid supplementation on intradermal test reactivity in atopic dogs: a preliminary study (Un estudio preliminar: efectos de la suplementacihn con acidos grasos esenciales en la reactividad del test intradermico en perros que padecian atopia.). Veterinary Dermatology 1993; 4: 191 - 197.1