GRE General Test: RC-273719 GRE Reading Comprehension

At the Shadybrook dog kennel, all the adult animals were given a new medication designed to reduce a dog’s risk of contracting a certain common infection. Several days after the medication was administered, most of the puppies of these dogs had elevated temperatures. Since raised body temperature is a side effect of this medication, the kennel owner hypothesized that the puppies’ elevated temperatures resulted from the medication’s being passed to them through their mothers’ milk.
Which of the following, if true, provides the most support for the kennel owner’s hypothesis?