METHODS OF ASSAYING MOTION SICKNESS PREVENTIVES ON DOGS

Abstract

The details of assay methods used since 1942 to test the effectiveness of motion sickness preventives in dogs are described.Animals first were classified according to their susceptibility to motion. Over a three year period dogs of moderate or marked susceptibility show little variation in the response to swinging or to treatment. Dogs of low susceptibility may become adapted to motion and be effectively treated by reduced dosage when used repeatedly.All dogs were treated using V-12 ethyl-β-methylallylthiobarbituric acid as a standard. Complete protection followed oral doses ranging from 1.25 to 30 mgm./kgm. and no untoward side effects were produced. Dogs of lowest susceptibility were most readily protected—by doses up to 5 mgm./kgm. Moderately susceptible animals required up to 15 mgm./kgm. and markedly susceptible ones more than this dose.Comparative assays with two other barbiturates showed that the results were not consistent when tests were made on groups of dogs of different susceptibility. V-12 was relatively more effective when tested on dogs of greatest susceptibility. Assays on dogs of low susceptibility that are readily treated are probably of questionable accuracy.Reducing the degree of swinging by one-half allowed the dogs to be effectively treated by one-fourth of the former dosage. The relative difference in potency between V-12 and another barbiturate was reduced by the change in magnitude of the swinging.The size and amplitude of the swing has a marked influence on quantitative assays. The smaller the degree of motion, the greater the apparent potency of a drug. Individual susceptibility to motion of the dogs is also a factor in obtaining comparable results. The greater the susceptibility, the more accurate the determination and comparison. Such factors will markedly limit comparisons of results obtained by different workers.