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  • Author or Editor: Ellen C. Codner x
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Summary:

Results of an elisa for allergen-specific IgE were compared with results of an intradermal (id) allergy test in 5 clinically normal dogs and 36 dogs referred for evaluation of allergic dermatitis. The elisa had a sensitivity of 100% and a specificity of 0%. Agreement between id allergy test and elisa for positive and negative results ranged from 44 to 56% for pollens, 39% for house dust/dust mite, 22% for fungi, and 54% for fleas. Agreement between id allergy test and elisa scores for all pollens was only 10% greater than that expected by chance alone, and a κ value of 0.17 confirmed poor test agreement. The greatest disparity in results was seen in dogs with negative id and positive elisa results.

Median elisa absorbance values for 15 groups of related allergens were compared in 4 groups of dogs: clinically normal dogs, atopic dogs with positive id reactivity, suspected atopic dogs with negative id reactivity, and flea-allergic dogs. There was no significant difference in median elisa values between clinically normal dogs and flea-allergic dogs, or clinically normal dogs and atopic dogs for any allergen group. Although the elisa absorbance value for fungal antigens was significantly higher in dogs suspected of being atopic than in clinically normal dogs, there was no significant difference in median elisa values for any other allergen group.

These findings suggested the disparity between id allergy test and elisa results was primarily attributable to false-positive elisa reactions rather than greater elisa sensitivity. The cause for the high false-positive rate in the elisa was unknown, but did not appear to be induced by flea allergy. The elisa should not be used to confirm a diagnosis of atopy or to identify allergens for hyposensitization, because of poor test specificity. However, a negative elisa result may reliably rule out a diagnosis of atopy.

Free access
in Journal of the American Veterinary Medical Association

Summary

Fifty dogs underwent intradermal allergy testing with housedust mite and house dust extracts, using concentrations recommended by the manufacturer. Twelve dogs (group I) were healthy dogs obtained from a pound; 12 dogs (group II) were healthy, privately owned dogs; 15 dogs (group III) were suspected of being atopic and had had multiple positive reactions to intradermal injections of allergens of specific trees, weeds, grasses, or molds; and 11 dogs (group IV) were suspected of being atopic, but only had had positive reactions to intradermal injections of housedust mite, house dust, and flea antigen extracts. Use of the concentrations of housedust mite and house dust extracts currently recommended for intradermal allergy testing resulted in false-positive reactions in 14 of 24 (58%) and 12 of 24 (50%) healthy dogs tested, respectively. Differences in number of dogs with positive reactions or grade of reaction to housedust mite or house dust allergens were not detected between groups of healthy dogs (groups I vs II), between groups of suspected atopic dogs (groups III vs IV), or between healthy dogs and dogs suspected of being atopic (groups I and II vs III and IV). Therefore, clinical importance of positive results of intradermal allergy testing of house dust or housedust mite allergens was equivocal for dogs suspected of being atopic.

Threshold concentrations for intradermal allergy testing were determined in 24 healthy dogs (group I and II) by intradermal administration of 5 dilutions each of housedust mite extract and house dust extract. Positive test results to various concentrations of housedust mite extract were observed in 22 dogs at 1:1,000 wiv, 14 dogs at 1:5,000 wiv, 5 dogs at 1:10,000 ww, 4 dogs at 1:25,000 wv, and 1 dog at 1:50,000 ww. Positive test results to various concentrations of house dust extract were observed in 21 dogs at 500 protein nitrogen units (pnu)/ml, 12 dogs at 100 pnu/ml, and 3 dogs at 50 pnu/ml, but none of the dogs had positive results at 20 and 10 pnu/ml, respectively.

Threshold concentrations for housedust mite (1:50,000 w/v) and house dust (20 pnu/ml) extracts were subsequently used for intradermal allergy testing of 9 dogs (group V) that were considered to be atopic and that had had multiple positive test results after intradermal injection of specific allergens. Positive reactions to intradermal injections of threshold concentrations of housedust mite and house dust extracts were observed in 6 of 9 and 7 of 9 atopic dogs, respectively. Analysis of the results was suggestive that house dust and housedust mite extracts can be properly diluted to threshold concentrations for intradermal allergy testing without adversely affecting their diagnostic value. Lower concentrations of housedust mite and house dust extracts than are currently recommended should be used for intradermal allergy testing to avoid false-positive results.

Free access
in Journal of the American Veterinary Medical Association

Summary

Urinary protein-to-creatinine ratios and serum albumin concentrations were measured in 8 adult male dogs experimentally inoculated with Ehrlichia canis. Urinary protein concentration increased significantly, but transiently, during the acute phase of infection. Urinary protein-to-creatinine ratios were highest (mean, 8.6) during the third and fourth weeks after infection, and decreased to < 0.5 by 6 weeks after infection. Correspondingly, albumin concentration decreased significantly during the acute phase. Serum albumin concentrations were lowest (mean, 2.1 g/dl) the fourth week after infection and increased to > 3.0 g/dl by 11 weeks after infection.

There was an inverse linear correlation between urinary protein-to-creatinine ratio and serum albumin concentration. The magnitude of proteinuria and its inverse relationship with serum albumin concentration suggested that hypoalbuminemia associated with acute E canis infection may be attributable primarily to increased renal loss of protein, rather than decreased hepatic synthesis as previously suggested.

Another dog was subsequently inoculated with E canis from 1 of the experimentally infected dogs and a renal biopsy was performed during peak proteinuria (urinary protein-to-creatinine ratio = 22 and serum albumin = 1.1 g/dl). Immunofluorescent staining revealed mild to moderate deposits of anti-canine IgM, and to a lesser extent, anti-canine IgG and complement factor C3 in the glomerular tufts and mesangium. Ultrastructural evaluation revealed distortion and fusion of podocyte foot processes and increased microvilli on podocytes. These morphologic changes were consistent with transient glomerular leakage of protein of a magnitude that would significantly contribute to hypoalbuminemia during acute E canis infection. An underlying immunologic mechanism was suggested by positive glomerular immunofluorescence and previously described histologic findings.

Free access
in American Journal of Veterinary Research

Summary

Seven atopic dogs underwent intradermal allergy testing with 46 inhalant antigens before and after administration of a tiletamine/zolazepam solution (4 mg/kg of body weight, IV). This anesthetic protocol had no significant effect on the intradermal response caused by histamine, whole flea extract, or various inhalant allergens. Short-acting chemical restraint induced by the drug combination facilitated the intradermal testing procedure.

Free access
in Journal of the American Veterinary Medical Association