Answer:
Stratified
Step-by-step explanation:
In stratified sampling, a population is divided into subgroups or strata, based on peculiar characteristics or attributes that is shared by all members put into that strata. In other words, members in a strata are placed together based on specific and distinctive attributes that defer from other members of another strata.
In the case of the employee working at an animal hospital, the sample described in the question that she uses can be said to be stratified, as dogs with brown hair are placed in a strata.