Effects of routine prophylactic vaccination or administration of aluminum adjuvant alone on allergen-specific serum IgE and IgG responses in allergic dogs

OBJECTIVE: To determine the acute corn-specific serum IgE and IgG, total serum IgE, and clinical responses to s.c. administration of prophylactic vaccines and aluminum adjuvant in corn-allergic dogs. ANIMALS: 20 allergic and 8 nonallergic dogs. PROCEDURE: 17 corn-allergic dogs were vaccinated. Eight clinically normal dogs also were vaccinated as a control group. Serum corn-specific IgE, corn-specific IgG, and total IgE concentrations were measured in each dog before vaccination and 1 and 3 weeks after vaccination by use of an ELISA. The corn-allergic dogs also had serum immunoglobulin concentrations measured at 8 and 9 weeks after vaccination. Twenty allergic dogs received a s.c. injection of aluminum adjuvant, and serum immunoglobulin concentrations were measured in each dog 1, 2, 3, 4, and 8 weeks after injection. The allergic dogs were examined during the 8 weeks after aluminum administration for clinical signs of allergic disease. RESULTS: The allergic dogs had significant increases in serum corn-specific IgE and IgG concentrations 1 and 3 weeks after vaccination but not 8 or 9 weeks after vaccination. Control dogs did not have a significant change in serum immunoglobulin concentrations after vaccination. After injection of aluminum adjuvant, the allergic dogs did not have a significant change in serum immunoglobulin concentrations or clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: Allergen-specific IgE and IgG concentrations increase after prophylactic vaccination in allergic dogs but not in clinically normal dogs. Prophylactic vaccination of dogs with food allergies may affect results of serologic allergen-specific immunoglobulin testing performed within 8 weeks after vaccination.     

Comparison of intradermal testing and serum testing for allergen-specific IgE using monoclonal IgE antibodies in 84 atopic dogs

OBJECTIVE: To compare an ELISA measuring serum allergen-specific IgE with intradermal skin testing in canine atopic dermatitis. PROCEDURE: Eighty-four dogs with the clinical diagnosis of atopic dermatitis underwent intradermal skin testing and serum testing for allergen-specific IgE. Tests were performed in a blinded fashion. Positive reactions were compared and the sensitivity and specificity of the serum test (using intradermal skin test as the standard) were determined overall and for individual allergen groups (grass pollens, weed pollens, tree pollens, house dust mites and fleas). RESULTS: The sensitivity of the ELISA overall was 90.4%. Evaluating the individual allergen groups, the sensitivity for dust mite hypersensitivity was 95.1%, for fleas 85.4%, for tree pollens 84.3%, for grass pollens 95.1% and for weed pollens 96.4%. The specificity was 91.6% overall, for dust mites 96.3%, for fleas 92.7%, for tree pollens 95.2%, for grass pollens 94% and for weed pollens 80.7%. CONCLUSION: The evaluated ELISA seemed reliable for the diagnosis of atopy in practice and can be recommended as a screening test prior to intradermal skin testing or for use in dogs when immunotherapy is not a therapeutic option.     

Factors affecting allergen-specific IgE serum levels in cats

Pruritic skin diseases are common in cats and demand rigorous diagnostic workup for finding an underlying etiology. Measurement of a serum allergen-specific IgE in a pruritic cat is often used to make or confirm the diagnosis of a skin hypersensitivity disease, although current evidence suggests that elevated allergen-specific IgE do not always correlate with a clinical disease and vice versa. The aim of the study was to to assess the possible influence of age, deworming status, lifestyle, flea treatment, and gender on allergen-specific IgE levels and to evaluate the reliability of IgE testing in predicting the final diagnosis of a pruritic cat. For this purpose sera of 179 cats with pruritus of different causes and 20 healthy cats were evaluated for allergen-specific IgE against environmental, food and flea allergens using the Fc-epsilon receptor based enzyme-linked immunosorbent assay (ELISA) test. The results of the study showed positive correlation between age, outdoor life style, absence of deworming, absence of flea control measures and levels of allergen-specific IgE. Gender and living area (urban versus rural) did not seem to affect the formation of allergen-specific IgE. According to these findings, evaluating allergen-specific IgE levels, is not a reliable test to diagnose hypersensitivity to food or environmental allergens in cats. On the contrary, this test can be successfully used for diagnosing feline flea bite hypersensitivity.     

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.     

Prevalence of and risk factors for increased serum levels of allergen-specific IgE in a population of Norwegian dogs

Background

The importance of different allergens in association with IgE production and canine atopic dermatitis (CAD) has been poorly studied and few studies exist on factors influencing allergen-specific IgE antibodies in serum. The aim of this cross-sectional study was to investigate the prevalence of elevated IgE levels to different environmental allergens in Norwegian dogs with a suspicion of CAD. The secondary aim was to identify risk factors associated with elevated serum levels of allergen-specific IgE.

Results

The study sample consisted of serum from 1313 dogs of 161 different breeds. All samples were submitted for serologic IgE-testing (Fc epsilon R1 alpha-based ELISA) based on suspicion of CAD. Overall, 84.3% of the dogs had elevated IgE levels to one or more of the allergen(s). The predominant allergens amongst the positive results were the indoor allergens (Acarus siro 84.0%, Dermatophagoides farinae 80.2%, Tyrophagus putrescentiae 79.9%). Sheep sorrel was the most commonly encountered outdoor allergen (40.0%). Only 2.6% of the dogs with elevated IgE levels were positive to flea saliva.The test results varied significantly depending on when the serum samples were taken. Samples taken during summer and autumn more often came out positive than samples taken during winter and spring. Geographical variations were also demonstrated. A greater proportion of females than males had positive test results, and more females than males tested positive to outdoor allergens. The mean age was significantly higher in the dogs testing positive than amongst the dogs testing negative. The allergen-specific IgE levels varied with breed. The boxer was the only breed with a significantly higher proportion of positive test results compared to the other breeds. Boxers also had a higher prevalence of elevated IgE levels to outdoor allergens, whereas the Rottweiler had a higher prevalence of elevated IgE levels to indoor allergens compared to the other breeds.

Conclusions

IgE hypersensitivity was most often associated with indoor allergens. Outdoor allergens were of minor importance and IgE reactivity to flea saliva was rare. Breed differences in allergen-specific IgE levels were identified. Season of sampling, and the dogs’ geographical localisation, sex and age also affected the results of the IgE analysis.     

IgE ELISA using antisera derived from epsilon chain antigenic peptides detects allergen-specific IgE in allergic horses

Equine disease with an allergic etiology is common. Environmental antigens most often implicated as allergens in horses include molds, dusty hay, grass pollen, hay dust mites, and insect saliva. Although intradermal testing with allergen is a useful diagnostic tool for some species, skin testing frequently produces false positive results in horses. Allergen deprivation as a diagnostic tool is often impossible and at best it is ineffective at diagnosing the specific allergic reactivity. Synthesis of IgE after exposure to allergen is the instigator of the allergic process. While IgE exerts its effect after binding strongly to mast cell Fc receptors, the presence of free IgE in the serum can be used to quantify and determine the allergen specificity of the allergic disease. A lack of widely available reagents for detection of equine IgE has limited this approach in horses. We have used the nucleotide sequence of equine IgE to prepare a peptide-based immunogen to elicit equine epsilon chain-specific antisera. Selection of peptides was based on antigenic attributes of the deduced amino acid sequence of the equine epsilon chain. Six peptides were selected for conjugation to carrier molecules and rabbit immunization. Of these, one peptide elicited antisera that was successfully used in enzyme linked immunosorbant assay (ELISA) to screen horse serum from 64 allergic horses for allergen-specific IgE. Twenty-four of the 64 horses showed positive reactivity to one or more of the following allergens: grass, grain mill dust, mosquito, and horsefly. This study demonstrates the usefulness of peptide-based immunogens for development of antisera to rare or difficult to purify antigens such as IgE. Resultant antisera has great usefulness in diagnostic assays for equine allergy and as a research tool.     

Dermatophagoides farinae-specific IgG subclass responses in atopic dogs undergoing allergen-specific immunotherapy

Atopic dermatitis (AD) is thought to be caused by immunologic abnormalities expressed as a Th1/Th2 cytokine imbalance in both humans and dogs. Several studies have focused on the therapeutic effects of IFNγ in human AD with successful results; however, the mechanism of action of IFNγ is not fully understood. We investigated the effect of recombinant canine interferon gamma (rCaIFNγ) on 10 dogs with AD and evaluated the ratio of IL-4 mRNA to IFNγ mRNA in peripheral blood mononuclear cells, serum total IgE levels, and histological changes in skin. After six injections of rCaIFNγ over a span of 2 weeks, seven of the 10 dogs showed improvement, and six of these seven dogs exhibited decreased IL-4:IFNγ mRNA ratios. Two of the three cases that did not improve had increased IL-4:IFNγ mRNA ratios. Total serum IgE levels were significantly decreased in nine of 10 cases. The number of IgE-positive cells detected by immunostaining and the number of mast cells in skin biopsy samples were decreased. A reduction of epidermal cell layers was demonstrated by histopathology after treatment. These results demonstrated that rCaIFNγ may be a novel safe and effective therapeutic option for the treatment of canine AD, and the mechanism of action of rCaIFNγ may be related to the modulation of Th2 cytokines to Th1 cytokines with the reduction of serum IgE production.
Funding: Self-funded.     

Quantitation of canine regulatory T cell populations, serum interleukin-10 and allergen-specific IgE concentrations in healthy control dogs and canine atopic dermatitis patients receiving allergen-specific immunotherapy

Canine atopic dermatitis (AD) shares many clinical and immunological similarities with human AD. Regulatory T cells (Treg) are a distinct lineage of T lymphocytes with various immunosuppressive properties including the down-regulation of allergic inflammation associated with IgE production. Antigen-induced Treg typically regulate immune homeostasis via productions of cytokines such as interleukin-10. Given the immunological similarities with human AD, it is likely that Tregs and the cytokines they produce play an important role in diseases of dogs as well. A cross-reactive FoxP3 antibody was used to identify a subset of CD4(+) T cells in the blood of both healthy dogs and dogs with atopic dermatitis undergoing immunotherapy over a year period. There was no significant difference in the Treg percentage over time in the healthy dogs. The immunotherapy group showed a significant increase in Treg percentage at 6, 9, and 12 months when compared to the healthy dogs. For the immunotherapy group, the mean Treg percentage at the beginning of the study was 4.94+/-0.71 and 10.86+/-2.73 at the completion. A commercially available ELISA kit was also used to quantitate the concentration of IL-10 in the serum of the same subsets of dogs. There was no significant difference in the IL-10 concentrations over time in the healthy dogs. The immunotherapy group showed a significant increase in serum IL-10 concentrations at 6, 9, and 12 months when compared to the control group. The mean serum IL-10 concentration at the initiation of immunotherapy was 20.40+/-3.52ngL(-1) and 37.26+/-15.26ngL(-1) at the completion of the study. The immunotherapy group also showed a significant decrease in serum IgE levels over the 1-year treatment period for specific allergens identified during ASIT. We conclude from these studies that similar to humans undergoing immunotherapy, increasing Treg populations likely play a significant role in the success of this particular type of therapy for atopic dermatitis and other allergic conditions.     

Comparison of intradermal and serum testing for allergen-specific IgE using a Fcepsilon RIalpha-based assay in atopic dogs in the UK

Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of an intradermal test (IDT) and an in vitro test in a large cohort of dogs. Dogs were intradermal tested with Greer allergens (Greer Labs Inc, Lenoir, NC, USA) using standard techniques. At the same time blood samples were drawn and submitted for evaluation by ELISA using the ALLERCEPT Definitive Allergen Panels for allergen-specific IgE, a commercial assay that uses a biotinylated recombinant extracellular domain of the high affinity Fc-epsilon receptor alpha chain protein (Fcepsilon RIalpha). The allergens used in the two tests included grass, tree and weed pollens, moulds, flea saliva/whole flea extract and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of the IDT for 265 dogs. The prevalence of positive reactions in the ELISA was equal to or greater than the results of the IDT in the case of almost all of the allergens, but two notable exceptions were the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. These two allergens were the most common positive reactions by IDT (prevalence D. farinae 78.9%, D. pteronyssinus 66.4%). The results of the two tests were significantly different (McNemar's test, P<0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the IDT (where there were more than 3 dogs with positive reactions in both tests) varied between 19.3 and 77.1% (D. pteronyssinus 19.3% and D. farinae 67.9%) and the specificities varied between 64.2 and 96.6% (D. pteronyssinus 96.6% and D. farinae 89.3%).     

IgE reactivity to vaccine components in dogs that developed immediate-type allergic reactions after vaccination

Allergic reactions after vaccination are considered as an important practical problem in dogs; however, their immunological mechanism has not been well understood. The present study was designed to investigate the relationship between IgE reactivity to the vaccines and immediate-type allergic reactions after vaccination in dogs. Sera from 10 dogs that developed immediate-type allergic reactions such as circulatory collapse, cyanosis, dyspnea, facial edema, and vomiting within 1h after vaccination with non-rabies monovalent or combined vaccines and sera from 50 dogs that did not develop allergic reactions after vaccination were collected. Serum IgE reactivity to the injected vaccines was measured by fluorometric ELISA using a mouse monoclonal anti-dog IgE antibody. Then, IgE reactivity to fetal calf serum (FCS) and stabilizer proteins (gelatin, casein, and peptone) included in the vaccines was measured in sera that had high levels of IgE to the vaccines. Levels of serum specific IgE to the vaccines in dogs with immediate-type allergic reactions (59-4173 fluorescence units [FU], mean +/- S.D.: 992.5 +/- 1181.9 FU) were significantly higher than those in control dogs (38-192 FU, 92.4 +/- 43.3 FU) (P < 0.001). Of the eight dogs that developed immediate-type allergic reactions and had high levels of serum specific IgE to the vaccines, seven had specific IgE directed to FCS. The IgE reactivity to the vaccines in sera from these dogs was almost completely inhibited by FCS. The other one dog had serum IgE directed to gelatin and casein included in the vaccine as stabilizers. The results obtained in this study suggest that immediate-type allergic reactions after vaccination in dogs were induced by type I hypersensitivity mediated by IgE directed to vaccine components. In addition, FCS, gelatin, and casein included in vaccines could be the causative allergens that induced immediate-type allergic reactions after vaccination in dogs.     

Total IgE and allergen-specific IgE and IgG antibody levels in sera of atopic dermatitis affected and non-affected Labrador- and Golden retrievers

Canine atopic dermatitis (CAD) is an allergic skin disease associated with IgE and IgG antibodies (Ab) to environmental allergens. The aim of this study was to determine which other factors influence serum Ab levels in CAD-affected and non-affected dogs as this has only been poorly investigated in dogs so far. Total and allergen-specific IgE levels and Dermatophagoides farinae (DF)-specific IgG1 and IgG4 were measured by ELISA in sera of 145 CAD-affected and 271 non-affected Labrador- and Golden retrievers. A multivariable logistic regression analysis including the factors age, breed, gender, castration, clinical CAD status and allergen-specific immunotherapy (ASIT) was performed. Golden retrievers had more frequently total (OR=1.87, 95% CI=1.26-2.87, p<0.01) and specific IgE levels above the threshold value than Labrador retrievers, suggesting that genetic factors influence IgE levels in dogs. Castration was generally associated with low Ab levels (OR=0.43-0.65, p<0.05). Surprisingly, dogs with CAD did not have increased odds for high IgE against any of the allergens tested. ASIT with DF was associated with high DF-specific IgG1 (OR=4.32, 95% CI 1.46-12.8, p<0.01) but was not associated with DF-specific IgG4 or decreased IgE levels. Further studies are needed to understand the role of allergen-specific IgE in CAD and of IgG1 in ASIT.     

Enzyme-linked immunosorbent assay for measurement of allergen-specific IgE antibodies in canine serum

A micro-ELISA, using horseradish peroxidase-conjugated anti-canine IgE and polystyrene microtitration wells for detection of allergen-specific IgE in canine serum, was developed. Specificity of anti-canine IgE was confirmed by reversed cutaneous anaphylaxis evaluations, gel-precipitation reactions, immunoelectrophoresis, immunoaffinity chromatography, and heat inactivation. Individual allergen blanks were used to account for variable nonspecific binding among various allergens, and results were normalized using 4 reference sera. Coefficients of variation for intra-assay and interassay variability ranged from 0.77 to 5.66% and 3.15 to 9.83%, respectively. Results observed with wells coated with mixtures of various allergen extracts yielded results approximately equal to results (average) of wells containing individual components. Agreement between ELISA and skin test results ranged from 43 to 64%, depending on allergen used.     

Dermatophagoides farinae-specific IgG responses in atopic dogs undergoing allergen-specific immunotherapy with aqueous vaccines

The molecular and immunologic mechanisms associated with successful allergen-specific immunotherapy (ASIT) have not been completely elucidated. The aim of this study was to characterize the changes in Dermatophagoides farinae -specific IgG in atopic dogs undergoing ASIT using aqueous vaccines. Fifteen atopic dogs with a positive skin test reaction to D. farinae were treated with aqueous vaccines for a minimum of 2 months following a standard protocol. Serum samples were collected before and during therapy and used to probe Western blots containing separated proteins of D. farinae . IgG responses were detected using a polyclonal goat anticanine IgG antibody and a chromogenic substrate 3,3'-diaminobenzidine. The blots were analysed using a semiquantitative digital image analysis system that evaluated the number and molecular weight of bands, as well as their intensity, which was related to IgG concentration. Prior to ASIT, all dogs showed allergen-specific IgG responses to various antigens of D. farinae . During ASIT, there was a significant increase in the total quantity of D. farinae -specific IgG antibodies to various antigens from the mite ( P  = 0.015). Significant increases were observed for a 98-kDa band ( P  = 0.015), likely to be Der f 15; bands with molecular weights between 50 and 70 kDa ( P  = 0.012); and bands between 30 and 45 kDa ( P  = 0.035). These findings provide support for the hypothesis that ASIT induces IgG blocking antibodies to allergens known to be relevant in canine atopic dermatitis.     

Establishment of a quantitative ELISA for the measurement of allergen-specific IgE in dogs using anti-IgE antibody cross-reactive to mouse and dog IgE

As IgE plays a pivotal role in type I hypersensitivity-mediated allergic diseases, it is valuable to measure absolute quantity of serum antigen-specific IgE for clinical and research purposes. Here we describe a novel ELISA system that enables quantification of antigen-specific IgE in ng/ml in dogs. A newly developed monoclonal antibody (CRE-DM) was shown to recognize canine and mouse IgE equally in a dose dependent manner, but it did not recognize canine IgG. The reactivity of CRE-DM to canine IgE was also confirmed by an inhibition ELISA using canine IgE as an inhibitor and the maximum inhibition rate was 91.3%. In order to know whether canine IgE specific to an allergen could be quantitatively measured with an ELISA using CRE-DM, we established a quantitative ELISA that could measure canine IgE recognizing Cry j 1, one of the major allergens of Japanese cedar pollen. In this ELISA, a standard curve was created by using concentration-predetermined Cry j 1-specific monoclonal mouse IgE. According to the standard curve, the concentration of Cry j 1-specific IgE in dogs that were experimentally sensitized to Japanese cedar pollen could be calculated and determined in ng/ml. The specificity of the Cry j 1-specific IgE ELISA using CRE-DM was also confirmed by inhibition ELISA using canine IgE as an inhibitor and the inhibition rate was 97.0%. Reproducibility of the ELISA in three independent assays was determined using groups of pooled canine sera whose Cry j 1-IgE titers ranged from 155.9 to 888.2 ng/ml. Intra- and inter-assay reproducibility was determined with coefficient of variation ranging between 3.1-5.2% and 2.2-8.0%, respectively. These results demonstrated that the ELISA utilizing CRE-DM was a specific, reliable and robust new laboratory test that could quantify absolute amount of antigen-specific IgE in canine serum. The ELISA will serve as a useful tool in the clinics to evaluate the change of serum IgE titers during anti-allergic treatments as well as during seasonal fluctuation of allergen exposure.     

Effect of immunotherapy on the serum concentrations of allergen-specific IgG antibodies in dog sera

An ELISA assay which uses horseradish peroxidase conjugated anti-canine IgG and polystyrene microtiter wells for detection of allergen-specific IgG in the serum of dogs is described. Individual allergen blanks were used to account for the variable nonspecific binding among various allergens, and the results observed in milliunits of absorbance were normalized using four reference sera. The coefficients of variation for the intraassay and interassay variability ranged from 1.34 to 12.50% and 4.62 to 9.77%, respectively. The relationship between ELISA results and serum concentrations of allergen-specific IgG was quantified. IgG antibodies with specificity for various allergens were found in the majority of non-atopic individuals and in all atopic subjects. Specific immunotherapy resulted in a rise in the serum concentration of allergen-specific IgG.     

Serum anti‐Staphylococcus pseudintermedius IgE and IgG antibodies in dogs with atopic dermatitis and nonatopic dogs

Background – Dogs and humans with atopic dermatitis (AD) are predisposed to colonization and recurrent infection with Staphylococcus spp. Studies in humans suggest that staphylococcus‐specific immunoglobulin E (IgE) plays a key role in disease pathogenesis. Few such studies have been undertaken in dogs. Hypothesis/Objectives – The aim of this study was to compare levels of staphylococcus‐specific IgE and immunoglobulin G (IgG) in dogs with AD, nonatopic dogs with staphylococcal pyoderma, and nonatopic and noninfected control dogs. Animals – Sera were collected from 108 dogs with AD, 39 nonatopic dogs with staphylococcal pyoderma secondary to different underlying conditions, 67 age‐matched nonatopic control dogs, and nine control dogs reared in minimal disease conditions. Methods – Serum Staphylococcus pseudintermedius‐specific IgE and IgG antibodies were measured by enzyme‐linked immunosorbent assay. Results – Dogs with AD had significantly higher levels of anti‐staphylococcal IgE than nonatopic dogs with staphylococcal pyoderma and the two groups of control dogs. Levels of anti‐staphylococcal IgG were significantly higher in atopic dogs and nonatopic dogs with pyoderma compared with nonatopic control dogs and control dogs reared in minimal disease conditions, but there was no significant difference in levels of anti‐staphylococcal IgG between dogs with AD and nonatopic dogs with pyoderma. Conclusions and clinical importance – A significantly increased IgE response to S. pseudintermedius antigens in atopic dogs suggests an immunopathogenic role for anti‐staphylococcal IgE. The finding of elevated IgE and IgG in atopic dogs is also important as a prelude to studies on antigenic specificity and possible correlations with disease phenotype.     

Evaluation of serum allergen-specific IgE for the diagnosis of food adverse reactions in the dog

A new monoclonal enzyme-linked immunoassay (ELISA; CMG IMMUNODOT, Fribourg, Switzerland) measuring food antigen-specific serum IgE was used in an attempt to investigate food allergen-specific IgE in dogs. The serum of eight dogs with clinically proven adverse reactions to specific proteins was tested for beef, cow's milk, pork, lamb, hen's egg, soybean, fish mix (cod/sole), peanut, maize and wheat flour. The control group consisted of three healthy dogs, three dogs with nonallergic skin disease, two dogs with atopy, a cat and a horse. Only three mild positive reactions to beef, lamb and peanut, respectively, were found in this study; the sera were from two control dogs with the clinical diagnosis of dermatophytosis and atopy. None of the animals with confirmed food adverse reactions showed positive reactions. This study indicates that the diagnosis of food adverse reactions in the dog by measuring allergen-specific IgE with the used mononuclear ELISA is unreliable.     

Serum IgE and IgG responses to food antigens in normal and atopic dogs,and dogs with gastrointestinal disease

In human food allergy, with or without concurrent atopy, there may be significant increases in serum allergen-specific IgE. Serological methods have been tried but are not currently recommended for diagnosis of suspected food allergy in dogs. The aim of this study was to investigate humoral immune responses to food antigens in dogs. Serum IgG and IgE antibodies specific for food antigens were measured by enzyme linked immunosorbent assay (ELISA) using polyclonal anti-dog IgG and IgE reagents. Antigens tested were beef, chicken, pork, lamb, chicken, turkey, white fish, whole egg, wheat, soybean, barley, rice, maize corn, potato, yeast and cow's milk. Three groups were examined: normal dogs, dogs with atopic dermatitis (AD); and dogs with one of four types of gastrointestinal (GI) disease: small intestinal bacterial overgrowth (SIBO), inflammatory bowel disease (IBD), food-responsive disease, and infectious diarrhoea. Statistically significant differences in food-specific antibodies were not detected between the GI subgroups. There were statistically significant differences in the IgE concentration between the normal dogs, and dogs with atopic or GI disease, for all of the antigens tested. There were statistically significant differences in the average IgG concentrations between the normal dogs, and dogs with atopic or GI disease, for all of the antigens tested, except egg and yeast. The relationship of antigen responses for pooled data was analysed using principle component analysis and cluster plots. Some clustering of variables was apparent for both IgE and IgG. For example, all dogs (normal and diseased) made a similar IgG antibody response to chicken and turkey. Compared with other groups, atopic dogs had more food allergen-specific IgE and this would be consistent with a Th(2) humoral response to food antigens. Dogs with GI disease had more food allergen-specific IgG compared with the other groups. This may reflect increased antigen exposure due to increased mucosal permeability which is a recognised feature of canine intestinal disease.