Canine atopy is a multifactorial disease in which genetically predisposed dogs develop a combination of cutaneous immune responses
to environmental antigens. Although the clinical signs can often be controlled, managing atopic dogs can be frustrating. Dogs
usually require life-long therapy, and in most cases, a multimodal treatment plan is needed to yield optimal results.
Nutritional management is a simple but powerful tool in controlling pruritus in dogs with allergic conditions.1-3* In atopic dogs, feeding a diet that includes a specifically adjusted fatty acid ratio (omega-6:omega-3) has resulted in
a clinical response that compares favorably with other therapies, with satisfactory control of pruritus based on veterinarian
and client assessment observed a few weeks after the initial feeding.1 The recent double-blind study described below compares the performance of three commercial veterinary diets during in-home
management of clinical signs in atopic dogs (data on file, P&G Pet Care, 2008).
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Fifty-six client-owned, adult, atopic dogs were randomly assigned to be fed one of three commercial veterinary dry diets indicated
for nutritional management of allergic conditions (diet A, Iams® Veterinary Formulas Skin & Coat Response™ FP; diet B, ROYAL CANIN Veterinary Diet™ Canine Hypoallergenic HP 19™; diet C, Hill's® Prescription Diet® d/d® Potato & Salmon Formula Canine). Study groups were balanced by gender, age, and
atopy severity on the initial screening examination.
Dogs were fed only the study diet, treated for fleas and ticks, and on a heartworm preventive throughout the eight-week trial.
No additional treatments were initiated or changed during these studies. At weeks one, two, four, and eight, owners returned
to the clinic with their dogs, and both owners and veterinarians assessed the dog's clinical signs. Only the veterinarians'
assessment of clinical signs is reported here.
Pruritus, skin lesions, and overall severity of atopy were evaluated and assigned a score from zero to 100, with lower scores
indicating milder clinical signs and higher scores indicating more severe clinical signs. Dogs were assigned a numerical score
based on severity of their baseline clinical signs of 25 (mild), 50 (moderate), and 75 (severe). Most of the dogs were initially
classified as mildly or moderately affected.
Clinical signs were found to be affected by both diet and duration of feeding in this study. In dogs with higher baseline
scores, the response to the diet was more pronounced. Beginning after two weeks of feeding diet A, dogs that were moderately
to severely affected at baseline showed a significant lowering of mean scores for pruritus and overall severity of atopy that
were maintained over the study period. However, similarly affected dogs fed diet B showed no significant improvement in these
scores, and dogs fed diet C showed significant improvement only after four to eight weeks of feeding. All dogs fed all diets
showed significant improvement in skin lesion scores, compared with baseline, starting as early as week one and maintained
Feeding diet A also resulted in significantly greater improvement in mean scores for all three clinical signs, compared with
diet B, in dogs that were moderately to severely affected at baseline (see Table 1). By week four, the improvement in pruritus scores with diet A was approximately six times that of diet B, and the improvement
in skin lesion scores was approximately twice that of diet B. Dogs fed diet C did not show significant differences vs. diet
A in improvement of any of the clinical signs.
Table 1. Results of veterinary assessments of clinical signs. Bolded values are significantly different from baseline; a values
significantly different from diet B.