Effect of peripheral anosmia in dogs trained as flavor validators

The importance of olfaction in perception of flavor by flavor-validating dogs was studied. The flavor-validation technique is widely used by pet food manufacturers to determine if a given formula is perceived by dogs as having the flavor of a specific meat. Five Beagles were trained as flavor validators; 2 dogs were trained to select beef and 3 to select lamb from a panel of 4 meats. When the dogs had been trained to select the correct meat on 100% of the trials, they were made anosmic. Reversible peripheral anosmia was produced in the dogs by inflating a cuff on a surgically implanted tracheostomy tube. When the cuff was inflated, air entered the trachea via the tracheostomy tube, rather than via the nasal cavity, and the percentage of correct choices on the flavor-validating test fell to 62 +/- 14%. When the tracheostomy tubes were removed, performance returned to 100% correct. The nasal cavities of 3 dogs were infused with zinc sulfate to produce a more complete and longer-lasting anosmia. The percentage of correct choice on the flavor-validation test fell to 24 +/- 5%. These findings indicate that the flavor-validation test is based primarily on one sensory modality, that of olfaction; therefore, formulas selected by flavor-validating dogs may smell similar to the specific meat, but do not necessarily taste similar to that meat.