Percutaneous Test Research Articles

Grass pollen sensitization in dogs in Paraná, Brazil: comparison between percutaneous and intradermal testing

ABSTRACT Canine atopic dermatitis is an inflammatory, genetic, pruritic and chronic dermatosis that affects between 10 and 30% of dogs and one of the most important allergens is grass pollen. The objective of this study was to evaluate the sensitization to grass pollen allergens in dogs with canine atopic dermatitis and to compare intradermal skin test (IDT) with percutaneous test (PT). For this study, ten healthy dogs and 39 dogs with atopic dermatitis were tested. Dogs were submitted to IDT and PT for Lolium multiflorum, Cynodon dactylon and Paspalum notatum. The IDT and PT tests were compared using the Proportion Test. All healthy dogs were negative to both tests. Ten atopic dogs (25.6%) responded positively to the PT and none were positive in IDT. C. dactylon, L. multiflorum and P. notatum were responsible for positive reactions in 70%, 70% and 30% of positive dogs, respectively. The number of positive reactions in PT were statistically higher than IDT (P<0.05). In conclusion, grass pollen can be important source of allergens for dogs in Paraná state (Brazil) and the PT showed higher sensitization to grass pollen in dogs with atopic dermatitis than IDT.

Percutaneous prick test irritant threshold concentrations for eight allergens in healthy nonsedated dogs in the USA.

Percutaneous testing (PT) is preferred to intradermal testing in humans for the in vivo identification of allergen hypersensitivity, but the methodology has not been well described for use in dogs with atopic dermatitis. To identify the irritant threshold concentrations (ITC) of eight aeroallergens using a commercial prick test device in normal dogs. Twenty healthy, privately owned dogs. Percutaneous testing was performed using the GREER® Pick® System (Stallergenes Greer; Lenoir, NC, USA). Five dilutions of glycerinated extracts of Bromis inermis, Sorghum halepense, Chenopodium album, Ambrosia psilostachya, Salix nigra and Acer negundo, as well as four dilutions of Dermatophagoides farinae and D. pteronyssinus were included. Glycerinated histamine (6 mg/ml) and glycerin/Coca's solution were used for the positive and negative controls, respectively. Orthogonal wheal diameters were measured for each test site every 5 min for 25 min. Reactions were considered significant when the average wheal diameter was equal to or greater than the mean of the positive and negative controls. Significant reactions were noted in five of 20 (25%) of dogs. The ITC (≤10% of dogs reacting) were 1:20 w/v for B. inermis and S. nigra, 1:400 w/v for D. farinae and 1:200 w/v for D. pteronyssinus. These results suggest that the pollen allergens evaluated in this study can be used for PT at their undiluted concentration (1:20 w/v) with a reasonable assurance of few false positive reactions in dogs. Dust mites require dilution for testing at the ITC.

Comparison of intradermal and percutaneous testing to histamine, saline and nine allergens in healthy adult cats.

Intradermal testing (IDT) in cats has potential limitations; this has led to an interest in novel testing methods. A pilot study demonstrated that healthy cats produced reliable percutaneous glycerinated (PG) histamine wheals, whereas percutaneously applied glycerosaline did not lead to wheal formation. The purpose of this study was to determine if percutaneously applied aqueous and glycerinated allergens would lead to irritant reactions in healthy cats. Percutaneous testing (PCT) with both glycerinated and aqueous allergens and IDT were compared in twelve healthy cats. The lateral thorax was clipped and histamine, saline and nine allergens were tested in rows. Objective and subjective evaluations were performed at 15, 20 and 25 min, and 4 h. Results were evaluated as positive or negative at 15, 20, 25 min and 4 h. Skin test reactions for intradermal (ID) histamine wheals were larger when compared to PG and percutaneous aqueous (PA) at the immediate reading points (P < 0.05) subjectively and objectively; however, PG was not significantly different from ID when compared as either positive (2-4) or negative (0-1). PG histamine and allergen reactions, when present, were larger than equivalent PA reactions. PG and PA allergens did not cause irritant reactions at tested concentrations. Bassia scoparia (kochia), when tested at 1000 PNU/mL with IDT, was suspected to be an irritant. Percutaneously (PCT) applied allergens did not cause irritant reactions in healthy cats. PG histamine wheals, although smaller than ID histamine wheals, were easily recognizable and PCT was simple to perform.