Cross-reactivity of cat and dog allergen extracts. RAST inhibition studies with special reference to the allergenic activity in saliva and urine.

The commercial cat and dog allergen extracts are traditionally prepared from pelt, fur or dander. However, there is increased evidence of the allergenicity of saliva and urine of the animals. We have investigated 25 asthmatic children with a positive cat and/or dog RAST result. All 20 subjects with a positive cat RAST gave a positive skin prick test result to cat saliva, cat urine and cat hair. Analogously, all 20 subjects with a positive dog RAST had a positive skin reaction to dog saliva, urine and dander. In RAST inhibition experiments with dog and cat allergen discs, dog saliva appeared to be at least as potent as a commercial dog dander and hair extract, while cat saliva was less potent than the respective commercial extract. Both dog and cat salivas were clearly more potent than the respective urine. Significant cross-reactivity was observed between cat hair and dog dander in the RAST inhibition, whereas saliva and urine were shown to be more species-specific. An experimental dog dander preparation had about the same specificity as, and even higher allergenic activity than, that of dog saliva or urine. Our results suggest that saliva actually may be the best source of cat and dog allergen preparations. The importance of urine warrants further investigation.