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


OBJECTIVE
The purpose of this study was to determine if percutaneously applied aqueous and glycerinated allergens would lead to irritant reactions in healthy cats.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Department of Dermatology and Allergy, Veterinary Referral Center of Colorado, 3550 South Jason Street, Englewood, CO, 80110, USA. cgentry@vrcc.com.
Christina M
http://orcid.org/0000-0003-4398-2414
CM
Gentry
Department of Dermatology and Allergy, Veterinary Referral Center of Colorado, 3550 South Jason Street, Englewood, CO, 80110, USA.
Linda
L
Messinger
D000485:Allergens / Q000276:immunology*; D000818:Animals; D002371:Cat Diseases / Q000175:diagnosis* / Q000276:immunology; D002415:Cats; D003876:Dermatitis, Atopic / Q000175:diagnosis / Q000276:immunology / Q000662:veterinary*; D005260:Female; D006632:Histamine / Q000008:administration & dosage / Q000276:immunology*; D007428:Intradermal Tests / Q000662:veterinary*; D008297:Male; D012867:Skin / Q000187:drug effects; D012965:Sodium Chloride / Q000008:administration & dosage*
D000485:Allergens; D012965:Sodium Chloride; D006632:Histamine