Comparison of response to immunotherapy by intradermal skin test and antigen-specific IgE in canine atopy

The intradermal skin test (IDST) and serologic allergy test (SAT) has been developed for confirming a diagnosis of canine atopy and determining allergens for immunotherapy. To determine the prevalence of causative allergens for canine atopic dermatitis in Japan, IDST and SAT were performed with the CMG Immunodot strips on 95 atopic dogs using 9 allergens. In addition, we compared agreement rate, sensitivity and specificity between them (using IDST as the standard). The allergen most commonly positive in both tests was house dust mites (IDST: 69.5%, SAT: 48.4%). Moreover, Japanese cedar, mugwort and grass mix were detected as attendant causative allergens. Agreement rates between the two tests ranged from 67.4% to 96.8%; the overall mean agreement rate were 81%. SAT was shown to have sensitivity to IDST ranging from 16.7 to 68.2%. The specificities were very high for all allergens, on the order of 94.9-100% (median=98.7%). Finally, the efficacy of immunotherapy was evaluated on 27 atopic dogs based on IDST (15 dogs) and SAT (12 dogs) results. Overall, 60% (9/15) of the IDST group and 66.8% (8/12) of the SAT group experienced a 50% to 100% reduction in their symptomatology. No significant differences were found in response to immunotherapy during the follow-up period between allergen selection methods. These results indicate the value of serologic tests as an aid to identifying an allergen solution for immunotherapy.     

Results of intradermal tests in horses without atopy and horses with chronic obstructive pulmonary disease

OBJECTIVE: To compare results of intradermal tests (IDT), conducted using environmental allergens, in horses without atopy and horses with chronic obstructive pulmonary disease (COPD). ANIMALS: 38 horses (22 horses without atopy and 16 horses with COPD). PROCEDURE: All horses were examined (physical examination, hematologic examination, serum biochemical analyses, examination of bronchoalveolar lavage fluid). An IDT was conducted, using a full panel of 73 allergens consisting of grasses, weeds, trees, molds, and insects. Results of the IDT were evaluated 30 minutes and 4, 6, and 24 hours after injection of allergens. Horses without atopy were euthanatized, and gross and histologic changes of lung parenchyma were assessed. RESULTS: Horses without atopy had a greater number of positive immediate and late-phase reactions than did horses with COPD. Horses with COPD did not have a significantly greater number of positive reactions than horses without atopy at any time period for any allergen group (grasses, weeds, trees, molds, and insects). CONCLUSIONS AND CLINICAL RELEVANCE: Positive results of IDT document allergen-specific hypersensitivity but do not necessarily distinguish clinically relevant reactions from subclinical reactivity in horses with COPD. Interpreting the clinical relevance of results of IDT requires a thorough knowledge of the medical history, physical examination findings, and environment of each animal.     

Results of intradermal tests in horses without atopy and horses with atopic dermatitis or recurrent urticaria.

OBJECTIVE: To compare results of intradermal tests (IDT) for environmental allergens at 30 minutes and 4, 6, and 24 hours after injection in horses without atopy and horses with atopic dermatitis (AD) or recurrent urticaria (RU). ANIMALS: 22 horses without atopy, 10 horses with RU, and 7 horses with AD. PROCEDURE: In all horses, medical history was obtained, and results of physical examination, hematologic examination, serum biochemical analyses, examination of bronchoalveolar lavage fluid, and IDT with 73 allergens were examined. RESULTS: Horses with AD or RU had a significantly greater mean number of positive reactions for IDT, compared with horses without atopy. Horses with AD had a significantly greater number of positive reactions than horses without atopy in every allergen group at all time periods, except for molds at 4 and 24 hours. Horses with RU had a significantly greater number of positive reactions than horses without atopy in every allergen group, except for molds at 30 minutes and 4 and 6 hours, trees at 4 and 6 hours, and grasses at 4 hours. CONCLUSIONS AND CLINICAL RELEVANCE: A significantly greater number of positive reactions for IDT in horses with AD or RU, compared with horses without atopy, provides evidence of type-I IgE-mediated hypersensitivity for these diseases. Evaluation of results of IDT performed in horses with AD or RU is useful in determining specific allergens for the formulation of immunotherapy along with providing identification of allergens that could be useful when creating avoidance strategies.     

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.     

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%).     

Comparison of results for intradermal testing between clinically normal horses and horses affected with recurrent airway obstruction

OBJECTIVE: To evaluate differences in response to ID injection of histamine, phytohemagglutinin (PHA), and Aspergillus organisms between clinically normal horses and horses with recurrent airway obstruction (RAO). ANIMALS: 5 healthy adult horses and 5 adult horses with RAO. PROCEDURE: Intradermal testing (IDT) was performed on the neck with 2 positive control substances (histamine and PHA) and a mixture comprising 5 Aspergillus species. Four concentrations of each test substance plus a negative control substance were used. Equal volumes (0.1 mL) of each test substance were prepared to yield 15 syringes ([4 concentrations of each test substance plus 1 negative control substance] times 3 test substances) for each side of each horse (ie, 30 syringes/horse). Intradermal injections were administered; diameter of wheals was recorded 0.5, 4, and 24 hours after injection. RESULTS: Hypersensitive responses to ID injection of histamine were detected 0.5 hours after injection, and a delay in wheal formation after ID injection of Aspergillus mixture 24 hours after injection was detected in RAO-affected horses but was not observed in clinically normal horses. No differences were detected between the 2 groups after ID injection of PHA. CONCLUSIONS AND CLINICAL RELEVANCE: RAO-affected horses are hypersensitive to histamine, suggesting that RAO is associated with a heightened vascular response to histamine. Higher concentrations of Aspergillus mixture may be needed to detect horses that are sensitive to this group of antigens. Wheal reactions to Aspergillus may be a delayed response, suggesting that IDT results should be evaluated 0.5, 4, and 24 hours after ID injection.     

Comparison of serum and urinary concentrations of clenbuterol with and without concomitant administration of furosemide in horses

Furosemide is frequently used to control or prevent exercise-induced pulmonary hemorrhage in performance horses. The bronchodilating agent clenbuterol is also commonly used as a treatment for inflammatory airway disease in performance horses. Use of both medications is regulated by many racing authorities. The effects of concomitant administration of furosemide and clenbuterol on the pharmacokinetics of clenbuterol have not been well characterized. A study was designed to evaluate the influence of furosemide on serum and urine concentrations of clenbuterol after oral administration of clenbuterol and intravenous administration of furosemide in horses. Results indicated that urinary concentrations of clenbuterol in horses treated concomitantly with furosemide and clenbuterol were increased, whereas serum concentrations of the drug were decreased. These effects persisted during the study period and varied among horses.     

Detection of rotavirus in horses with and without diarrhea by electron microscopy and Rotazyme test

A total of 142 equine fecal samples (93 field fecal and 49 experimental fecal specimens) were examined for rotavirus using direct electron microscopy (EM) and the Rotazyme test. Eighty-six stool specimens were diarrhea samples. The Rotazyme test sensitivity and accuracy as compared to EM was determined by the visual (color reaction) and spectrophotometric methods. The overall agreement was 94.8% and 92.3% between EM and Rotazyme visual and spectrophotometric methods, respectively when suspect reactions (1 + color reaction or net absorbance between 0.05 and 0.1) were not included. The Rotazyme test is a quick, simple, and accurate diagnostic test for detection of rotavirus in equine fecal samples. It could be used by the equine practitioner with a minimum of laboratory facilities and by diagnostic and research laboratories.     

Duration of inhibition of immediate skin test reactivity by hydroxyzine hydrochloride in dogs

The duration of hydroxyzine-mediated suppression of the immediate hypersensitivity reaction in the skin of dogs was assessed by intradermal administration of various dilutions of histamine phosphate and of aqueous flea antigen in 18 dogs known to be allergic to fleas. Wheal diameters and scores were used to evaluate the strength of the resulting reactions. In most dogs, significant (P less than 0.05) inhibition lasted from 3 to 5 days after withdrawal from treatment. Some dogs took up to 9 days to equal or exceed their pretreatment wheal diameters and scores.     

Antibody levels by indirect ELISA test in Trypanosoma evansi infected horses following treatment with quinapyramine sulphate

An ELISA test was used to determine the persistence of antibody levels in horses following treatment for Trypanosoma evansi. In 17 horses with T. evansi from two farms treated and cured with quinapyramine sulphate, ELISA antibody levels fell progressively post-treatment, but remained with positive results for 22.6 months in one horse, 12.8 months in a second, 4.1 months in another four and 2.3 months in three, whilst the rest became negative at 2.3 months. In two horses that suffered a post-treatment infection relapse the decrease in ELISA levels was only temporary, and a new increase in antibody levels was proven. The follow-up of these antibody levels could prove useful in clinical cases and in epidemiological studies, as well as for assessing the efficacy of drug treatment.     

Artifactually increased serum bicarbonate values in two horses and a calf with severe rhabdomyolysis

Extremely high bicarbonate (HCO3-) and anion gap values were measured in two horses and a calf using the Hitachi 911 automated serum biochemistry analyzer. All three animals had severe muscle disease as evidenced by markedly increased aspartate aminotransferase and creatine kinase activities. Laboratory error was suspected as the source of the increased HCO3- because values calculated from blood gas analysis were normal. It was hypothesized that increased serum lactate dehydrogenase (LDH) activity and pyruvate concentration overwhelmed the oxamate LDH inhibitor in the enzymatic HCO3- assay, resulting in consumption of NADH and falsely elevated spectrophotometric reading. Serum LDH activity was markedly increased in all three patients. In an attempt to reproduce this interference in vitro, LDH and pyruvate were added to normal bovine serum. Bicarbonate concentration was artifactually increased in a linear, dose-response relationship proportional to the amount of LDH activity in the sample; addition of pyruvate augmented this increase. It was concluded that increased serum LDH activity and pyruvate concentration secondary to severe muscle disease can result in artifactual increases in serum HCO3- values obtained by routine enzymatic assay.     

Performance characteristics of a monoclonal antibody cocktail-based ELISA for detection of allergen-specific IgE in dogs and comparison with a high affinity IgE receptor-based ELISA

The purpose of this study was to define the operational and performance characteristics of a commercially available monoclonal antibody based (mac) ELISA for detection of allergen-specific IgE in dogs. The average intra-assay variance over 1 year was 9.7% (range 2.5–62.7%), while the interassay variance averaged 10.8% (range 8.1–13.8%). The average positive control responses observed for grass, weed, tree and mite allergens during each month remained relatively constant; the average monthly variance was 11.6% (range 8.3–19.2%) for grass pollens, 13.3% (range 9.1–20.4%) for weed pollens, 13.3% (range 9.8–18.2%) for tree pollens and 13.6% (range 8.9–18.7%) for mite allergens. The interlaboratory concordance of results for the macELISA was approximately 91%. The interlaboratory concordance of results comparing the macELISA and a high affinity IgE receptor-based ELISA was approximately 92%. The results demonstrate that the macELISA is reproducible and the results are comparable to the high affinity IgE receptor based ELISA within and between laboratories.