How to build a model's custom RESTAdapter depending on route?

I'm very new to Ember.js, so still getting the fundamentals down. I have a model, let's call it dog, whose data is coming from an external API. The API only allows you to get big dogs and small dogs separately:

http://ift.tt/1EMcXzD
http://ift.tt/1KcSKJj

If I were to have big and small routes of my own—each of which would get the appropriate list of dogs—how could I customize my DogAdapter's buildURL method to put together the correct API call depending on the current route?

This is a very simplified example, please let me know if anything needs to be clarified.