Comparison of Commercial Cat and Dog Extracts in Skin Prick Testing and Protein Electrophoresis
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Reese Bryan Lennarson, Gregory M. Metz, MD, Shahan Stutes, MD, Warren V. Filley, MD FAAAAI

Many different cat and dog allergens are available commercially for testing and treatment.  We aimed to study differences in skin prick testing (SPT) reactivity in a pool of patients to two cat extracts [Cat Hair 10,000 BAU/ml (Greer Labs) and AP Cat Pelt 10,000 BAU/ml (Hollister-Stier)]  and two dog extracts [AP Dog Hair-Dander (Hollister-Stier) and Dog Hair & Epithelia (Allergy Labs)].  We hypothesized that similarities or differences in reactivity could be explained by a comparison of extract protein profiles which were elucidated using electrophoresis.


Data was collected from skin testing results of 260 consecutive patients tested to both cat extracts and 334 consecutive patients tested to both dog extracts since December 2014.  A positive skin test result was defined as 3 mm greater than the skin test response to the negative saline control.  Electrophoresis was then performed on a number of commercially available cat and dog extracts.


We found that only 60% of patients with a positive SPT to cat had a positive skin test to both commercial cat extracts and only 51% of SPT positive dog patients were positive to both dog extracts. Conversely, cat and dog allergic patients were skin test positive to only one of two extracts in 40% and 49% of cases, respectively.  Electrophoresis illustrated major differences in protein composition for cat and dog extracts among products from different manufacturers.


Variable protein composition among commercial cat and dog extracts may explain inconsistencies in skin prick testing when using extracts from different manufacturers.