Dietary trials with a commercial chicken hydrolysate diet in 63 pruritic dogs

The owners of 63 pruritic dogs were instructed to feed them a chicken hydrolysate diet exclusively for six weeks as part of diagnostic investigations into non-seasonal pruritus. Ectoparasitism and microbial infections were eliminated during the dietary trial. The dogs' skin lesions, gastrointestinal signs and frequency of defecation were assessed and scores for pruritus were assigned before they started the diet and before and after they resumed their original diet. An adverse food reaction was diagnosed if the pruritus resolved while they were on the diet, but recurred when they resumed their original food regimen. Seventeen of the 63 dogs were withdrawn from the trial, including four which found the diet unpalatable; however, its palatability was reported to be good or excellent in 48 of the dogs. An adverse food reaction alone was diagnosed in nine (19.6 per cent) of the 46 dogs and another nine had an adverse food reaction and atopy. There were gastrointestinal signs in six of the nine dogs with an adverse food reaction, which resolved on the trial diet but recurred when they resumed their original diet.     

Development of Gastroscopic Food Sensitivity Testing in Dogs

The aims of this study were to develop a gastroscopic food sensitivity testing (GFST) technique for clinical use in dogs and to determine if the results of GFST were influenced by the feeding of a hypoallergenic diet immediately before the testing period ("unmasking"). The technical requirements for GFST were devised during a total of eight endoscopies performed in four healthy dogs. GFST was performed in anesthetized dogs in sternal recumbency. Food extracts were dripped onto the dependent aspect of the body of the stomach via plastic tubing passed through the endoscope. Changes were observed within 2 to 3 minutes of application, and included localized mucosal swelling and erythema, generalized mucosal erythema, and hyperperistalsis. The influence of "unmasking" was then examined in 6 atopic and 2 healthy dogs, which underwent GFST on three occasions, 4 weeks apart. Before the first and third testing periods, the dogs consumed a commercial dry dog food. For 5 days before the second testing period the dogs were fed a hypoallergenic elemental diet. Oral challenges were performed to identify which of the dogs had clinically overt immediate food sensitivity. Localized swelling was most frequently correlated with positive challenge PO. No positive reactions occurred in response to the negative control extract (lamb). The number of positive GFST results increased after feeding the hypoallergenic diet. In conclusion, these preliminary results indicate that GFST holds substantial promise for the diagnosis of immediate food sensitivities affecting the gastrointestinal tract. The sensitivity of the procedure appears to be enhanced by preceding testing with a hypoallergenic diet.     

Validity of skin testing for diagnosis of food allergy in dogs.

One hundred suspected allergic dogs were skin-tested with 9 food extracts, in addition to other inhalant and insect allergens. Forty-eight of the dogs had +2 or greater intradermal reactions to 1 or more food extracts at concentration of 1,000 protein nitrogen units/ml. Thirty of the food extract-positive dogs were fed a restrictive hypoallergenic diet. Of these 30 dogs, 3 improved, then allergy signs worsened when they were challenge-exposed with the original diet. Fifty-two dogs did not have skin test reactivity to any of the 9 food extracts. Of these 52 dogs, 35 were fed a restrictive diet. Six improved, then allergy signs worsened when dogs were challenge-exposed with the original diet. Skin-testing with selected allergenic food extracts was not useful in identifying food-sensitive dogs.     

Effect of an omega-3/omega-6 fatty acid-containing commercial lamb and rice diet on pruritus in atopic dogs: results of a single-blinded study.

A commercial, lamb and rice, dog food with an omega-6:omega-3 fatty acid ratio of 5.5:1 was fed in a single-blinded, self-controlled clinical trial to 18 atopic dogs. The pruritus in 8 of these dogs (44.4%) was satisfactorily controlled within 7 to 21 d, returned within 3 to 14 d after the diet was withdrawn, and was again controlled when the diet was reinstated. Plasma and skin levels of examined fatty acids changed in all 18 dogs when their diet was switched to the test diet. Dogs responding to the test diet had a different pattern of fatty acid change as compared to the dogs which failed to respond to the diet, suggesting that there are subsets of atopic dogs with different fatty acid metabolism capabilities.     

Comparison of procedures for assessing adequacy of dog foods.

Dog foods with similar claims for nutritional adequacy were tested by chemical analysis and the American Association of Feed Control Officials' growth trial. All foods tested were similar chemically, however, dogs given one regionally marketed food had lower growth rate and food efficiency as well as suboptimal PCV and hemoglobin values during the growth trial. Pups fed this diet also had clinical signs typical of zinc and copper deficiencies. We concluded that American Association of Feed Control Officials' approved feeding tests provide valid assessment of pet food quality, and procedures involving only chemical analysis or calculated values may not.     

Food sensitivity in the dog: a quantitative study

Over a period of one year, 251 dogs were presented to a UK-based dermatology referral clinic. Eighty-five of these were either diagnosed as having symptoms compatible with atopy (58 dogs), or suffered from chronic otitis or recurrent pyoderma. All 85 were placed on a carefully restricted diet for eight to nine weeks in an attempt to establish whether the symptoms were due to food sensitivity. In total, 19 were shown to have food sensitivity, representing 7.6 per cent of all dogs presented to the clinic, and one-third (32.7 per cent) of those dogs with signs compatible with a diagnosis of atopy. In five dogs with proven food sensitivity, otitis was the principal clinical sign and, in two others, recurrent pyoderma. In the population studied, labradors appeared to be predisposed to the condition. Improvement was monitored by asking owners to assess their dog's symptoms on an ordinal scale of pruritus. In those cases in which food sensitivity was confirmed, significant reduction in pruritus occurred. Most of these could be maintained long term on a commercial restricted-component diet. Particular effort was made to ensure owner compliance with the diet trials, using an explanation and model based upon a Venn diagram showing assumed links between atopy and several 'flare factors'. It was found that this approach significantly enhanced client understanding and cooperation. It is concluded that a careful approach, monitored by active clinical audit, will help to establish the true incidence of food sensitivity.     

Evaluation of selected-protein-source diets for management of dogs with adverse reactions to foods.

OBJECTIVE: To evaluate 3 commercially available selected-protein-source diets as maintenance diets in dogs with pruritus caused by adverse food reactions. DESIGN: Randomized crossover trial. ANIMALS: 40 dogs > 6 months of age with pruritus caused by adverse reactions to foods. PROCEDURE: Diagnosis was confirmed by use of diet elimination and provocation studies. Subsequently, dogs were fed 3 commercial diets for 3 weeks each in a randomized, blinded, crossover trial. Dogs were evaluated for pruritus, vomiting, diarrhea, and flatulence. RESULTS: Pruritus recurred in 52.5% of dogs fed a chicken-rice diet, 47.5% of dogs fed a catfish-rice diet, and 85% of dogs fed a venison-rice diet. Overall 95% of the dogs could be managed successfully with at least 1 of the 3 diets. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that commercially available limited-allergen diets with selected protein sources may be appropriate for long-term management of pruritus caused by adverse food reactions. Testing of various protein sources is usually required.     

Patch testing and allergen-specific serum IgE and IgG antibodies in the diagnosis of canine adverse food reactions

Adverse food reaction (AFR) is a common differential diagnosis for pruritic dogs. The only way to diagnose AFR is an elimination diet of 6-8 weeks with a protein and a carbohydrate source not previously fed. In humans, patch testing has been shown to be a useful tool to diagnose food allergies. In veterinary medicine, serum food allergen-specific antibody testing is widely offered to identify suitable ingredients for such diets. The aim of this study was to determine sensitivity, specificity, negative and positive predictability of patch testing with and serum antibody testing for a variety of common food stuffs. Twenty-five allergic dogs underwent an elimination diet and individual rechallenge with selected food stuffs, food patch testing and serum testing for food-antigen specific IgE and IgG. Eleven clinically normal control dogs only were subjected to patch and serum testing. The sensitivity and specificity of the patch test were 96.7 and 89.0% respectively, negative and positive predictability were 99.3 and 63.0%. For IgE and IgG the sensitivity was 6.7 and 26.7%, specificity were 91.4 and 88.3%, the negative predictive values 80.7 and 83.7% and the positive predictive values were 15.4 and 34.8%. Based on these results, a positive reaction of a dog on these tests is not very helpful, but a negative result indicates that this antigen is tolerated well. We conclude that patch testing (and to a lesser degree serum testing) can be helpful in choosing ingredients for an elimination diet in a dog with suspected AFR.     

Diagnostic testing of dogs for food hypersensitivity

Thirteen food-allergic dogs were studied to evaluate the efficacy of feeding a commercially available egg and rice diet, intradermal skin testing, and serologic testing by ELISA for diagnosing and/or characterizing food hypersensitivity. Feeding of a home-cooked whole lamb meat and rice diet for 3 weeks, followed by challenge with each dog's regular diet, served as the standard for diagnosing food hypersensitivity. Each dog underwent provocative testing with 6 individual ingredients to determine as many of its dietary allergens as possible. Prior to skin testing and serologic testing by ELISA, most dogs had been recently exposed to the offending diet and subsequently manifested clinical signs of allergy. All dogs that tolerated the aforementioned commercial diet were exposed to it for at least 7 weeks; 84.6% of food-hypersensitive dogs ate the commercial diet with impunity. Of the 2 reactors to the commercial diet, only 1 became pruritic in response to provocation testing with chicken eggs. Low sensitivity and high specificity were found for skin testing and the ELISA, indicating a lack of true- and false-positive reactions. Neither the positive nor negative predictive values adequately predicted positive and negative reactions, respectively, for either test. On the basis of these results, the commercial diet, skin testing, and anti-IgE ELISA cannot replace an owner-prepared food elimination diet for food hypersensitivity testing in dogs.     

Orally administered clonidine as a secretagogue of growth hormone and as a thymotrophic agent in dogs of various ages

The growth hormone (GH) secretagogue activity of variable dosages of clonidine (16.5, 50, 150, and 450 micrograms/kg of body weight), given orally mixed with the daily food ration, was evaluated in young and old dogs. Significant (P less than 0.05) increase in plasma GH concentration was detected at all dosages tested in young dogs and in response to all but the lowest dose tested in the old dogs fed the clonidine-containing diet. Old dogs had plasma GH concentration that exceeded that of young dogs when higher doses of clonidine were used. A clonidine (100 micrograms/kg)-supplemented diet was fed to middle-aged dogs twice daily for 30 days. Significant (P less than 0.01) increase of plasma GH concentration was observed on the first day of the feeding trial, but was undetectable by day 30. After feeding the clonidine-enhanced diet for 30 days, the effects on thymic morphology were variable, and there was no effect on plasma thymulin titer. Clonidine-fed dogs had significantly increased lymphocyte blastogenic responsiveness to mitogens, compared with that of control dogs, when evaluated as stimulation index.     

Food allergen-specific serum IgG and IgE before and after elimination diets in allergic dogs

Serum food allergen-specific antibody testing is widely offered to identify suitable ingredients for diets to diagnose adverse food reaction (AFR) in dogs with allergic skin disease. Antibody concentrations in blood samples obtained during an unsuccessful diet to help in the choice of diet changes may be influenced by the previous diet. The objective of this paper was to measure food antigen-specific IgE and IgG for the most commonly used 16 food antigens before and after an elimination diet. Levels of food-specific serum IgE and IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA). Dogs had detectable IgE antibodies to beef, pork, lamb and cows' milk; and detectable IgG antibodies to beef, pork, lamb, cows' milk, chicken and turkey. Of 19 dogs with complete data sets, 14 dogs showed clear improvement during diet and in 7 dogs AFR could be diagnosed by deterioration on rechallenge and subsequent improvement on refeeding the diet. Serum was obtained before and 6-8 weeks after beginning such a diet. There was no significant difference in pre- and post-diet levels for any of the individual allergens nor for the total IgE and IgG concentrations of all antigens (P=0.55 and P=0.53 respectively). In these 19 dogs in which an elimination diet was used for the diagnosis of food allergy and in which 14 were probably food allergic and 7 were proven food allergic there were no significant differences in food-specific antibodies before and after an elimination diet of 6-8 weeks.     

Evalution of a Commerical Canned Lamb and Rice Diet for the Management of Adverse Reactions to Food in Dogs*

Abstract— A commercial canned lamb and rice diet was fed to 20 dogs with previously diagnosed determatologic problems due to adverse reactions to food. Fifteen of the 20 dogs had concurrent atopy and flea allergy which were being treated with hyposensitization and agressive flea control. Palatability and acceptability were good in most of the dogs. Recurrent of previous dermatologic signs did not occur in 75 per cent (15/20) of the dogs while they were fed the diet. Gastrointestinal side effects, specifically diarrhea, caused the owners to stop feeding the diet in four dogs. Overall, 60 per cent (12/20) experienced some gastrointestinal signs during the diet trail.     

A retrospective analysis of case series using home-prepared and chicken hydrolysate diets in the diagnosis of adverse food reactions in 181 pruritic dogs

The purpose of this retrospective study was to compare home-prepared and chicken hydrolysate diets in the diagnosis of canine adverse food reactions (AFR). Seventy-two dogs were fed home-prepared diets and 109 were fed hydrolysate. Owners chose the type of diet at presentation, and ingredients of home-prepared diets were selected depending on each dog's dietary history. Ectoparasitic infestations and microbial infections were treated during the trials. Cutaneous and gastrointestinal signs and pruritus scores were recorded before starting the diet, 6 weeks into the trials and after provocation with the original diets. AFR was diagnosed if pruritus resolved during the trial and recurred on dietary provocation. The dropout rate was lower for home-prepared diets although not statistically significant (18.1% home prepared; 24.7% hydrolysate, P=0.377). AFR alone was diagnosed in 10 dogs (17%) using home-prepared diets and in 15 (18.3%) fed the hydrolysate. Gastrointestinal problems were more frequent in dogs with AFR than in dogs without AFR (P=0.001). Another 11 dogs (18.6%) in the home-prepared diet group and 20 (24.4%) in the hydrolysate diet group had AFR concurrent with other pruritic diseases, mainly atopy. The similar frequencies of AFR diagnosis in the two groups (P=0.837 AFR; P=0.416 concurrent AFR) indicate that the chicken hydrolysate diet may be a valuable alternative to home-prepared diets in the diagnosis of canine AFR. Prospective cross-over studies are warranted to confirm these findings.     

Effects of diets with different calcium and phosphorus contents on the skeletal development and blood chemistry of growing great danes

The skeletal development of three groups of great dane dogs, fed a diet composed according to the published nutritional requirements for dogs (controls) or with increased calcium or calcium and phosphorus content, was examined radiographically, histologically and biochemically. The diets were fed from the time the dogs first began eating food in addition to their dam's milk, until they were 17 weeks old. Thereafter, the calcium and phosphorus intakes of the dogs in the high calcium groups were normalised for a further 10 weeks. The dogs fed the high calcium diet without a proportionally high phosphorus intake became hypercalcaemic and hypophosphataemic, and had severe disturbances in skeletal development, growth, and mineralisation which were typical for rickets. After their calcium intake was normalised the lesions of rickets resolved but osteochondrotic lesions became apparent. The dogs fed the high calcium and phosphorus diet became slightly hypophosphataemic, their growth was retarded, and they had disturbances in skeletal development resembling osteochondrosis, which had only partly resolved after 10 weeks on the normal calcium and phosphorus diet.     

Oxidized dietary fat,alkaline phosphatase concentrations and performance in racing greyhounds

Racing dogs are often fed raw meat. Raw meat may become oxidized because it contains no preservatives but few studies have examined the effect of feeding oxidized food to dogs. This study was originally designed to determine the effect of different concentrations of dietary fat on greyhound performance. After the experiment had been completed, however, it was discovered that the peroxide values (PV) of both diets were elevated indicating that fat oxidation had been present. This study was considered to have value, therefore, because it compared performance and blood parameters in eight trained Greyhounds fed either a high fat moderately oxidized (HFMO) diet (43%ME fat with PV of 44 mEq/kg) or a medium fat highly oxidized (MFHO) diet (31%ME fat with PV of 211 mEq/kg) for 8 weeks per diet in a randomized cross‐over design. Dogs were raced over 500 m twice weekly. Race times over the last 4 weeks of each diet period and blood parameters before racing during the last week of each diet period were compared. Dogs fed the MFHO food ran 0.04 m/s slower (p = 0.06) and serum alkaline phosphatase concentrations were higher (149 vs. 56 U/L; p < 0.0001) than in dogs fed the HFMO diet. Further evaluation is needed to determine whether lower dietary fat or increased oxidation was responsible for the altered performance but oxidation of the food should be considered as one possible explanation for an increase in serum alkaline phosphatase during a diet trial.     

Plasma lipid concentrations,macronutrient digestibility and mineral absorption in dogs fed a dry food containing medium-chain triglycerides

In a cross-over trial with feeding periods of 2 weeks, six healthy dogs were fed a dry food with a total fat content of 13.4% and containing either 5% (w/w) corn oil (11% of dietary metabolizable energy) or an isoenergetic amount of medium-chain triglycerides (MCT). The two diets were supplied on a restricted basis. There were no food refusals and no diet difference in palatability was observed. The MCT vs. Corn oil did not significantly influence plasma lipid concentrations, but group mean triacylglycerol concentrations were increased by 23% (p=0.074). The MCT consumption did not affect the apparent digestibilities of crude protein and soluble carbohydrates and had no impact on the absorption of calcium, magnesium and phosphorus. The incorporation of MCT into the diet produced a slight increase (by 0.9 percentage units) in crude fat digestibility (p=0.061). It is concluded that MCT at the present inclusion level may not have disadvantageous effects.     

Flow cytometric analysis of lymphocyte proliferative responses to food allergens in dogs with food allergy

Two different allergy tests, antigen-specific immunoglobulin E quantification (IgE test) and flow cytometric analysis of antigen-specific proliferation of peripheral lymphocytes (lymphocyte proliferation test), were performed to examine differences in allergic reactions to food allergens in dogs with food allergy (FA). Thirteen dogs were diagnosed as FA based on clinical findings and elimination diet trials. Seven dogs clinically diagnosed with canine atopic dermatitis (CAD) were used as a disease control group, and 5 healthy dogs were used as a negative control group. In the FA group, 19 and 33 allergen reactions were identified using the serum IgE test and the lymphocyte proliferation test, respectively. Likewise, in the CAD group, 12 and 6 allergen reactions and in the healthy dogs 3 and 0 allergen reactions were identified by each test, respectively. A significant difference was found between FA and healthy dogs in terms of positive allergen detection by the lymphocyte proliferation test, suggesting that the test can be useful to differentiate FA from healthy dogs but not from CAD. Both tests were repeated in 6 of the dogs with FA after a 1.5- to 5-month elimination diet trial. The IgE concentrations in 9 of 11 of the positive reactions decreased by 20-80%, whereas all the positive reactions in the lymphocyte proliferation test decreased to nearly zero (P<0.05), suggesting that lymphocytes against food allergens may be involved in the pathogenesis of canine FA.     

Clinical evaluation of dietary modification for treatment of spontaneous chronic renal failure in dogs

OBJECTIVE: To determine whether a diet used for dogs with renal failure (renal food [RF]) was superior to an adult maintenance food (MF) in minimizing uremic crises and mortality rate in dogs with spontaneous chronic renal failure. DESIGN: Double-masked, randomized, controlled clinical trial. ANIMALS: 38 dogs with spontaneous chronic renal failure. PROCEDURE: Dogs were randomly assigned to a group fed adult MF or a group fed RF and evaluated for up to 24 months. The 2 groups were of similar clinical, biochemical, and hematologic status. The effects of diets on uremic crises and mortality rate were compared. Changes in renal function were evaluated by use of serial evaluation of serum creatinine concentrations and reciprocal of serum creatinine concentrations. RESULTS: Compared with the MF, the RF had a beneficial effect regarding uremic crises and mortality rate in dogs with mild and moderate renal failure. Dogs fed the RF had a slower decline in renal function, compared with dogs fed the MF. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary modifications are beneficial in minimizing extrarenal manifestations of uremia and mortality rate in dogs with mild and moderate spontaneous chronic renal failure. Results are consistent with the hypothesis that delay in development of uremic crises and associated mortality rate in dogs fed RF was associated, at least in part, with reduction in rate of progression of renal failure.     

Essential fatty acids supplementation in different-stage atopic dogs fed on a controlled diet

The aim of this trial was to evaluate the effects of polyunsaturated fatty acid (PUFA) supplementation in different-stages atopic dogs fed on a controlled diet. Twenty-two non-seasonal atopic dogs of different breeds and ages were included in the 2-month trial. All the patients were given an essential fatty acid (EFA) supplementation [17 mg/kg eicosapentaenoic acid (EPA) + 5 mg/kg docosahexaenoic acid (DHA) + 35 mg/kg gammalinolenic acid (GLA)], the global (diet + supplementation) omega-6 to omega-3 ratio was 5.5-1. Two groups of dogs were considered: group A 'pre-immunotherapy' (15 cases) included dogs with early stages atopy, which had not been submitted to any treatment yet; group B 'post-immunotherapy' (seven cases) included dogs with chronic atopy immunotherapy non-responsive. Clinical evaluations were performed at the beginning, on day 30 and at the end of the trial. Blood serum fatty acids profile was determined at the beginning and at the end of the study. Better clinical results were obtained in group A, a great difference was found between the two groups on pruritus score. Serum arachidonic acid (AA) was significantly lower at the end of the trial in group A while GLA was significantly higher in group B. We hypothesized that different-stages atopic dogs could have different response to EFA supplementation, maybe because of a different fatty acids metabolism. Early stages cases seem to be more responsive to EFA supplementation.     

Comparison of a commercial limited-antigen diet versus home-prepared diets in the diagnosis of canine adverse food reaction

The objective of the present study was to compare the efficacy of a commercial limited-antigen diet (Eukanuba Veterinary Diets Response Formula FP/Canine, The Iams Company) with home-prepared diets in the diagnosis of adverse food reaction in dogs. The study was conducted in two phases. The first phase utilized 28 dogs fed a home-prepared diet to enable a diagnosis of adverse food reaction. Dogs diagnosed from this phase were entered into the second phase in which these dogs were fed the commercial limited-antigen diet. Owners of 10 of the 28 dogs quit Phase 1 before it could be completed, and one case was eliminated because extended treatment with steroids was required. Eight of the remaining 17 (47 %) dogs were diagnosed with an adverse food reaction. A reaction occurred in four of eight dogs fed the test diet in Phase 2. These results demonstrated the difficulties encountered by owners and veterinarians attempting to feed dogs home-prepared diets. In addition, the results of the study suggest that the occurrence of adverse reactions to fish could make it a less desirable ingredient as a limited antigenin canine diets.