Serum IgE and IgG responses to dietary antigens in dogs with and without cutaneous adverse food reactions.

BACKGROUND: It is suspected that many canine cutaneous adverse food reactions (CAFR) are true immunological hypersensitivities; however, few specific dietary allergens have been identified. OBJECTIVE: To compare serum immunoglobulin (Ig)E and IgG reactivity to specific food antigens in privately owned dogs with and without CAFR. ANIMALS: Eighteen adult dogs with nonseasonal pruritus recruited from a hospital population. METHODS AND MATERIALS: Dogs were fed an extensively hydrolysed poultry-based diet exclusively for 12 weeks. Serum was collected at the beginning of the trial. Canine atopic dermatitis extent and severity index and pruritus Visual Analog Scale scoring were performed at the beginning and end of the trial. Immunoblotting was performed to identify IgE and/or IgG binding to specific proteins in beef, egg, milk, chicken, pork, soy and wheat extracts. RESULTS: A CAFR (defined as an unequivocal relapse of pruritus after dietary challenge) was diagnosed in 10 dogs, with 60% relapsing when fed chicken-based diets. Binding of subjects' IgG to almost all proteins in all extracts was seen regardless of reported dietary history. Few proteins were exclusively or predominantly bound by IgE in CAFR dogs. Exceptions included a 42 kDa band (chicken), a 52 kDa band (beef), a 46 kDa band (beef and milk) and a poorly defined high molecular weight protein or proteins (beef and milk). CONCLUSION: This study demonstrated three protein bands and a poorly defined band predominantly recognized by sera from dogs with CAFR relative to non-CAFR dog sera. Almost all proteins were bound by IgG in all dogs, suggesting prior exposure to unreported foods.

Extensive protein hydrolyzation is indispensable to prevent IgE-mediated poultry allergen recognition in dogs and cats.

BACKGROUND: The central premise for the commercialization of diets with hydrolyzed ingredients is that the small-sized digested peptides would be unable to crosslink allergen-specific IgE at the surface of tissue mast cells and induce their degranulation. Evidence for the validity of this concept to diagnose food allergies in dogs and cats is limited, however. Our objectives were to study the recognition of standard and variably hydrolyzed poultry extracts by sera from dogs and cats with elevated chicken-specific serum IgE. RESULTS: Forty sera from dogs and 40 from cats with undetectable, low, medium or high serum levels of chicken-specific IgE were tested by ELISA on plates coated with the positive controls chicken, duck and turkey meat extracts and the negative controls beef meat (dogs) or wheat (cats). Plates were also coated with a non-hydrolyzed chicken meal, and mildly- or extensively-hydrolyzed poultry feather extracts. The frequencies of dogs with positive IgE against the various extracts were: chicken meat: 100%, duck and turkey meats: 97%, beef meat: 3%, non-hydrolyzed chicken meal: 73%, mildly-hydrolyzed poultry feathers: 37% and extensively-hydrolyzed poultry feathers: 0%. For cats, these respective percentages were (with wheat replacing beef as a negative control): 100, 84, 97, 7, 7, 0 and 0%. To detect any allergenic cross-reactivity between poultry meat-based and feather hydrolysate-derived extracts, an IgE ELISA inhibition was also done. Ten canine sera with the highest level of anti-poultry IgE in the previous experiment were incubated overnight with a previously optimized 50 µg amount of each of the extracts used above. We performed ELISA on plates coated with chicken, duck or turkey meats with or without inhibitors. The median inhibition percentages after incubation with the non-hydrolyzed chicken meal were ~22%, with the mildly-hydrolyzed poultry feathers: 14-22%, and those with the extensively-hydrolyzed poultry feathers: 5 to 10%; the last inhibition level was similar to that of the beef meat negative control. CONCLUSIONS: Altogether, these results suggest that an extensive-but not partial-hydrolyzation of the poultry feather extract is necessary to prevent the recognition of allergenic epitopes by poultry-specific IgE.

Efficacy of a Therapeutic Diet on Dogs With Signs of Cognitive Dysfunction Syndrome (CDS): A Prospective Double Blinded Placebo Controlled Clinical Study.

Cognitive dysfunction syndrome (CDS) is a common condition in senior dogs, which may be analogous to dementia such as Alzheimer's disease (AD) in people. In humans, AD has been associated with many risk factors such as reduced cerebral glucose metabolism, docosahexaenoic acid (DHA) deficiency, chronic oxidative stress, and chronic inflammation. By targeting some of these risk factors, we have developed two nutritional solutions (medium chain triglyceride, MCT and Brain Protection Blend, BPB) to enhance cognitive function and slow aging-induced cognitive decline. These have been positively evaluated in colony housed senior dogs and cats. The objective of this clinical study was to evaluate the effects of diets with MCTs and the BPB on client-owned dogs with CDS. Participating veterinary clinics screened senior dogs for signs of CDS as determined by a Senior Canine Behavior Questionnaire and a Canine Medical Health Questionnaire. Eighty-seven dogs were randomly enrolled into one of three diet groups with 29 dogs per group: Control, 6.5% MCT oil + BPB (6.5% MCT diet), 9% MCT oil + BPB (9% MCT diet). Diets were fed for a period of 90 days, and each dog's CDS signs were re-evaluated at day 30 and day 90. All 6 categories of the CDS signs were significantly improved (p <0.05) in the dogs given the 6.5% MCT diet at the end of the 90-day study. Control only improved in 4 out 6 categories. The 9% MCT diet only improved in dogs that accepted the diet. The results from this dog study confirm the benefits of MCT and BPB in managing clinical signs of CDS in dogs. The results support our hypothesis that targeting known risk factors associated with brain aging and AD is able to improve symptoms of CDS in dogs. These data may facilitate the development of similar nutrient blends to manage MCI and AD.

Therapeutic effects of an alpha-casozepine and L-tryptophan supplemented diet on fear and anxiety in the cat.

Objectives This study assessed the anxiolytic effectiveness of a test diet (Royal Canin Feline Calm diet) supplemented with L-tryptophan and alpha-casozepine. Methods Subjects were 24 cats that were classified as mildly or markedly fearful based on the presence of a person in their home room. Three different protocols were used to assess anxiety: (1) evaluation of the response to a human in the cat's home room (home room test); (2) analysis of the response to placement in an empty test room (open-field test); and (3) analysis of the response to an unfamiliar human (human interaction test). All three protocols were first run at baseline, and the results were used to assign the animals to control and test diet groups that showed equivalent fear and anxiety. Both groups were retested on the three protocols after 2 weeks (test 1) and again after 4 weeks (test 2). Results The diet groups differed for two behavioral measures in the open-field test: inactivity duration and inactivity frequency. The control group showed statistically significant increases in inactivity duration between baseline and test 1 and baseline and test 2, while the group fed the test diet showed a marginally not significant decrease in inactivity duration between baseline and test 1 and a not significant decrease for test 2. There was also a significant increase in inactivity frequency between baseline and test 1 in the test diet group and marginally not significant decrease in the control group. There were no differences between groups in the approach of the cats toward people for the home room test and the human interaction test. Conclusions and relevance These results suggest that the test diet reduced the anxiety response to placement in an unfamiliar location, but that fear in the presence of an unfamiliar person was not counteracted by the diet.

A moderate fat, low-energy dry expanded diet reduces gain in body condition score when fed as part of a post neutering weight-control regimen in growing pet cats.

Neutering of cats has been associated with significant weight gain in the weeks following surgery. The present study aimed to evaluate the effectiveness of a moderate fat, low-energy dry expanded diet in reducing weight gain in growing pet cats when fed as part of a weight-control regimen over the 6 months post-neutering. Cats in participating primary care veterinary hospitals were enrolled at neutering and assigned to receive one of the two dietary treatments based on the hospital of origin. Owners of cats in the treatment group were instructed to feed the trial diet at maintenance (324·7 kJ/kg BW(0·711) per d). Instructions for the control group were to feed the cat's regular diet according to the manufacturer's recommendations. Body weight and condition were evaluated by veterinarians at enrolment, 2-weeks, and 1-4 and 6 months after surgery. Body condition score (five-point scale) was compared between enrolment and each subsequent visit, controlling for enrolment age and sex. Percentage change in body weight was evaluated via multivariate mixed modelling to account for repeated measures. A total of 187 cats (eighty-seven females and 100 males) with a mean age of 5·2 (sd 0·8) months and mean weight of 2·8 (sd 0·6) kg from fifty-one hospitals completed the trial. The odds of being scored as overweight were 4·1 times as great for cats in the control v. treatment groups (95 % CI 2·1, 8·2). Percentage change in body weight differed significantly with enrolment age (P = 0·007) and approached significance between diet groups (P = 0·08). Cats fed the trial diet had a significantly reduced incidence of overweight in the 6 months following neutering.