The phrase "primary breed" refers to the main or most important breed of an animal or organism. It is the breed that is considered the fundamental or primary type. Full definition
Visual breed identification in dogs is unreliable, so for most dogs we are only guessing at primary breed. (arl-iowa.org)
Chihuahuas were once again the second highest intake type, followed by Labrador retriever as primary breed, then German shepherd dogs, followed by the global term «terrier» in the fifth spot. (aspcapro.org)
The figures given are for primary breed label, which includes dogs that are mixes or that have a secondary breed label. (houndmanor.com)