CytoSport is the largest American manufacturer of ready-to-drink protein drinks. Their most well-known brand is MUSCLE MILK, but Canadian consumers cannot buy MUSCLE MILK. Instead, CytoSport brands this drink in Canada as MUSCLE MLK.

This is done to distinguish their product from actual milk. There are numerous labelling requirements for dairy products in Canada. These regulations, by the Canadian Food Inspection Agency, include a definition of milk: "Milk" or "whole milk", as used in the manufacture of dairy products, means the normal lacteal secretion, free from colostrum, obtained from the mammary gland of an animal” and controls how the term can be used and what other information must appear on the packaging.

Even after CytoSport rebranded their product as MUSCLE MLK in Canada, they still faced a challenge in the form of an opposition filed with the Trademarks Opposition Board (TMOB) by the Dairy Farmers of Canada. The Dairy Farmers argued that MUSCLE MLK was not registrable in Canada pursuant to Section 12(1)(b) of the Trademarks Act because it was deceptively misdescriptive of the nature of the goods because Canadian consumers would likely believe that a product called MUSCLE MLK would contain milk.

CytoSport won the opposition and filed evidence of many definitions of milk other than dairy milk, including coconut milk, milk of magnesia and more. CytoSport has faced an uphill battle to have their brand registered in Canada, but with one rebranding and a successful defence to an opposition, their brand now appears to be on firm footing in Canada.