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theVeterinarian a r e g ula r c l i n i c a l u p da t e b ro u gh t t o you b y Eukanub a Ve te r inar y Die ts issue 5, march 2009 Dietary management of canine atopic dermatitis By Professor Dr. Ralf S. Mueller, DipACVD, FACVSc, DipECVD Welcome to theVeterinarian from Eukanuba Veterinary Diets. Introduction The aim of theVeterinarian is to give the busy clinician quick and Canine atopic dermatitis (fig 1) is a easy to read practical information, and top-tips, on common clinical problems. common skin disease in small animal practice.1 It is defined as a genetically predisposed inflammatory and pruritic allergic skin disease with characteristic clinical features and is most commonly Figure 1. A young English (but not necessarily) associated with IgE antibodies to environmental allergens.2 Bull Terrier with atopic dermatitis Clinical Presentation and Medical Management Clinically, pedal (fig 2), ventral (fig 3) and facial pruritus as well as otitis externa are hallmarks of the disease. Secondary infections are frequently seen and with the associated self-trauma and chronic inflammation also contribute to the clinical About the author signs. Atopic dermatitis can be treated symptomatically with anti-inflammatory Prof. Dr. Ralf S. Mueller graduated in Munich, Germany, in 1985 and worked in drugs or with allergen-specific immuno- several large and small animal practices before completing a residency in veterinary therapy (ASIT). ASIT is to date the only dermatology at the University of California, Davis. Later, he was director of the specific treatment for canine atopic der- Animal Skin & Allergy Clinic, a dermatology referral practice in Melbourne, Australia, together with his partner and wife Dr. Sonya Bettenay. He joined matitis.3 Symptomatic treatment of atopic the faculty at Colorado State University, USA in 1999. Since 2004 he is dermatitis comprises oral and topical Chief of Dermatology & Allergy at the veterinary faculty, Ludwig glucocorticoids,4 cyclosporin A,4,5 antihis- Maximilian University in Munich, Germany. tamines,2,6 fatty acid supplementation2,7 as well as topical treatment with antipruritic Dietary management of canine atopic dermatitis results of this study, in addition to the Figure 2. Alopecia and swelling of a distal Figure 3. Hyperpigmentation, erythema extremity due to atopic dermatitis and and alopecia of the ventrum due to chronic conventional therapies, changing the diet secondary infection in an 8 year old pruritus in an atopic 8 year old female of dogs with atopic dermatitis may be a female Golden Retriever. Golden Retriever. useful adjunctive measure to therapy. Discussion shampoos. The frequently observed secon- patient-pruritus levels using a visual ana- Diets manufactured for dogs with atopic dary infections must also be addressed. logue scale. dermatitis typically have a higher content More recently, diets recommended to help of essential fatty acids (EFA) which may with the management of canine atopic Results explain their influence on allergic skin dermatitis have been introduced to the After eight weeks on the new foods, dogs disease.10 Proposed mechanisms of action market. assigned to diet A (n=14) showed signifi- of essential fatty acids include modulation cantly less pruritus (p = 0.019), diet B of eicosanoid production, inhibition of Dietary Management: new study (Eukanuba Veterinary Diets® Dermatosis FP; cellular activation and an increase in n=12) fed dogs had a significant decrease epidermal barrier function. EFA’s can In one multi-centered, double-blinded, in both the CADESI and pruritus scores influence the immune system by acting as randomised study, fifty dogs with atopic (p = 0.043 and p = 0.012 respectively). second messengers, regulators of signal dermatitis were fed either one of three Diet D (n=12) significantly reduced the transducing molecules or transcription commercial veterinary diets marketed for CADESI score and diet C (n=12) had no factors.11 In a recent study, it was shown dogs with atopic dermatitis (diets A-C) or significant effect on the pruritus or that EFA’s inhibit T-cell proliferation in a widely distributed supermarket food CADESI scores (figs 4, 5). Based on the dogs.12 Thus, it is possible that the improve- (diet D) for eight consecutive weeks.8 Atopic dermatitis was diagnosed in these dogs using Willemse’s criteria and through the exclusion of differential diagnoses. Flea and tick control using a monthly fipronil spot-on was administered to all dogs prior to and during the study period. Monthly evaluations included veterinary graded lesional scores, using an established scoring system (CADESI = Canine Atopic Dermatitis Extent and Severity Index)9 and owner evaluated Top Tips • Any atopic dog may develop secondary infections at any time. Thus, with increased pruritus, cytology is essential to diagnose these secondary infections. • Dietary management is particularly important in dogs allergic to both environmental and dietary antigens. In these dogs, the smallest amounts of antigens can lead to an allergic flare and thus great care has to be taken in selecting medications, supplements and treats without flavours. • The dose of a medication that is costly or has a high rate of adverse effects may be reduced if concurrent antihistamines, essential fatty acids, topical therapy and/or dietary management are used. Dietary management of canine atopic dermatitis ment of the dogs in this study was due to Conclusion the feeding of a good quality essential Feeding a special formulated canine skin fatty acid source. Calculation of n-6:n-3 diet may be helpful alongside medical 13 ratios have been reported to be of value. therapies in decreasing pruritus and skin In this study, the amount and type of fatty lesions in individual dogs with atopic acids in the diets varied. Eukanuba FP dermatitis. contained a relatively low n-6:n-3 ratio of Did you know ? • That just one flavoured heart worm prevention or antibiotic tablet may cause increased pruritus and allergen-specific IgE in sensitive dogs? 2.7:1. The other two test diets A and C • That an increased intake of essential fatty acids in atopic dogs may reduce the need of glucocorticoids to control clinical signs? had a ratio of 4.7:1 and 5.4:1 respectively. The improvement seen with Eukanuba FP may support lower ratios than 5:1. Calculation of n-6:n-3 ratios may not be the only story, as the long chain fatty acids are more potent substrates for eicosanoid production than their shorter counterparts.14 Diet A and Dermatosis FP contained the highest percentage of the omega-3 References eicosapentaenoic acid, docosahexaenoic acid and other long chain fatty acids. It is possible that this contributed to the clinical effects seen while using these two diets. Figure 4. Diet A 40 Dermatosis FP Diet D Diet C CADESI scores at 35 week 0 and week 8 CADESI score 30 of the study for 25 each diet group. 20 *P <0.05 15 10 * * 5 0 0 Pruritus score 9 8 Diet A 0 8 Dermatosis FP 0 8 Diet C 0 8 Week Figure 5. Diet D 8 Pruritus scores at 7 week 0 and week 8 6 of the study for 5 each diet group. * 4 *P <0.05 3 * 2 1 0 0 8 0 8 0 8 0 8 Week 1. Health status and population characteristics of dogs and cats examined at private veterinary practices in the United States. Lund EM, Armstrong PJ, Kirk CA, et al JAVMA 1999; 214: 1336-41. 2. The ACVD task force on canine atopic dermatitis: forewords and lexicon. Olivry T, DeBoer DJ, Griffin CE, et al. Vet Imm and Immunopath 2001; 81: 143-6. 3. Effect of hyposensitisation on atopic dermatitis in dogs. Willemse A, Van den Brom WE, Rijnberk A. JAVMA 1984; 184: 1277-80. 4. Evidence-based veterinary dermatology: a systematic review of the pharmacotherapy of canine atopic dermatitis. Olivry T, Mueller RS. Vet Derm 2003; 14: 121-46. 5. A systematic review and meta-analysis of the efficacy of cyclosporine for the treatment of canine atopic dermatitis. Steffan J, Favrot C, Mueller RS. Vet Derm 2006; 17: 3-16. 6. Use of antihistamines to control pruritus in atopic dogs. Paterson S. JSAP 1994; 35: 415-9. 7. Effect of omega-3 fatty acids on canine atopic dermatitis. Mueller RS, Fieseler KV, Fettman MJ, et al. JSAP 2004; 45: 293-7. 8. The evaluation of commercially available veterinary diets recommended for dogs with atopic dermatitis. Glos K, Linek M, Loewenstein C, Mayer U, Mueller RS. Vet Derm 2008; 19: 280-7. 9. Validation of CADESI-03, a Severity Scale for Clinical Trials Enrolling Dogs with Atopic Dermatitis. Olivry T, Marsella R, Iwasaki T, Mueller RS. Vet Derm 2007; 18: 78-86. 10.Nutritional Management of Canine Atopy in 47 Dogs: A Retrospective Study. Rosychuk RAW. Recent Advances in Canine and Feline Nutrition, Iams Nutrition Symposium 2000; III: 287-91. 11.Fatty acids and immune responses a new perspective in searching for clues to mechanism. Hwang D. Annual Reviews of Nutrition 2000; 20: 431-56. 12.The influence of polyunsaturated fatty acids on the T-cell response in dogs with atopic dermatitis. Stehle ME, Goebel T, Hancaruk M, Mueller RS. Vet Derm 2007; 18: 194. 13.Evaluation of effects of dietary n-6 to n-3 fatty acid ratios on leukotriene B synthesis in dog skin and neutrophils. Vaughn DM, Reinhart GA, Swaim SF, et al Vet Derm 1994; 5: 163-73. 14.Fat and fatty acids. Bauer JE. Nutrient requirements of dogs and cats. Washington: The National Academies Press, 2006: 81-109. ResearchNews from P&G Pet Care manufacturers of Eukanuba, Iams and Eukanuba Veterinary Diets Surgical and dietary management of canine perianal fistula disease Canine perianal fistula disease (PAF) is a chronic, debilitating, painful and progressive disease of the anus, perianal skin, anal sacs and adjacent tissues (fig 1). It is characterised by inflammation, ulceration and draining tracts. In one study 84% of cases were German Shepherd Dogs.1 Irish Setters, retrievers and spaniels are also affected.2 A recent independent study reported the of clinical signs while only 21% continued results of feeding Eukanuba Veterinary to have intermittent licking, diarrhoea, Diets Dermatosis FP Fish & Potato (fig 2) constipation, tenesmus or decreased in conjunction with en bloc surgical excision anal tone on digital examination. ® of all visibly diseased tissue and bilateral anal saculectomy in a series of PAF dogs.3 The authors concluded that dogs with Antibiotics were prescribed prior to the PAF can be successfully treated with en study. Dermatosis FP was fed exclusively bloc surgical excision of diseased tissue to all but one dog before the study and and bilateral anal saculectomy; and feeding continued post-operatively for 1 long-term perioperative feeding of a novel year. fish and potato diet (Dermatosis FP), enriched with omega-3 fatty acids, Thirty-three dogs completed the study of supports the management of the disease. which 97% had concurrent anal sac disease Figure 1. Perianal fistula disease. at the start. At the 3-month post-operative Image courtesy of Professor Dick White, evaluation 70% had no clinical signs or Dick White Referrals, Newmarket, UK evidence of fistulas. At the 1-year evaluation 88% had complete resolution of visible fistula disease, 79% were completely free PAF is a well-documented disease but its cause is still poorly understood and includes, (1) an anatomic predisposition of a broad-based tail, low tail carriage and increased density of apocrine sweat glands in the zona cutanea, (2) an immunemediated basis is suggested due to a positive response to prednisolone, azothioprine, cyclosporine and tacrolimus.2,3 Treatment options include medical and surgical but both have potential complications making alternative treatment strategies desirable. Figure 2. Eukanuba Veterinary Diets® Dermatosis FP Fish & Potato References 1. Pathology of surgically resected tissue from 305 cases of anal furunculosis in the dog. Day MJ & Weaver BMQ. JSAP 1992; 33: 583-589 2. Rectoanal disease. Zoran DL. Textbook of Veterinary Internal Medicine, 6 th Ed, 2005; Eds Ettinger SJ & Feldman EC: 1408-1420 3. Long-term evaluation of canine perianal fistula disease treated with exclusive fish and potato diet and surgical excision. Lombardi RL & Marino DJ. JAAHA 2008; 44: 302-307