Pure bred has been a concept for animals since 1839. With the purpose of promoting clearly defined and healthy breading lines over just two animals thrown together. But in relatively recent history how to know if a dog is pure bred has become a problem. Currently the only way to get a pure bred dog is to buy one through a Kennel Club. Each country has their own Kennel Club; for example the AKC is the American Kennel Club, and the CKC is the Canadian Kennel Club. The first Kennel Club was founded back in 1873 in London, since then the Kennel Club has grown significantly. 

References

https://www.merriam-webster.com/dictionary/purebred

https://www.purebreddog.ca/

       There are many reasons that pure bred matters. The ones listed here are not an exhaustive list. 

       For us the largest reason that pure bred matters is the health aspect. Pure bred animals need to not have genetic diseases (in most countries) which ensures a healthier animal. Additionally, the parent animals are required to be of a certain age before breeding and experience no more than a specified number (according to species) of pregnancies in a year, be kept in a manner that the animal can be healthy and happy (which is why pet stores are not allowed), as well as have regular vet checkups and, if required treatments. All of these factors contribute towards a healthier animal physically and mentally.

      Another large reason is that for hypoallergenic animals it is impossible to guarantee the hypoallergenic trait unless you know the pedigree of the animal for a significant amount of history. One great-great-great-great-great-great-great grandparent can pass down genes that can manifest in a not hypoallergenic animal. We are not comfortable selling animals with the hypoallergenic label under any circumstances besides pure bred for this reasons. It would be traumatizing to both the family and the puppy to discover after they fell in love, that they could not remain together. If hypoallergenic is important to you it pays to invest in a pure bred instead of heartbreak. While hypoallergenic is the aspect that concerns us the most there are many surprises that could crop up in your animal if they are not pure bred.

        An additional significant motivation for us to choose pure bred is that humane circumstances are enforced. Anyone can have a kennel in which they can breed any way they like. They could breed animals too young or too often, keep the animals in cages for their entire lives, and a host of other horrible things. Getting a pure bred animal ensures that your pet was bred humanely. 

      And the last reason for us is that we are interested in skill contests for our animals and these are only enterable with a pure bred animal. If you are interested in beauty contests you can also only enter if they are pure bred. This is to try to force those who only see profit that can come from these shows into treating their animals humanely. There are a huge variety of contests that you can enter your animal in if they are pure bred. 

      Another reason that you might choose a pure bred animal is that the Kennel Clubs have requirements for the breeders. If the breeders do not follow these rules they can be fined, but consistently ignoring them will result in a revoked membership, which means that they can no longer register or represent their animals as pure bred. These rules do what I have already stated above, but they also protect the buyer. Breeders are required to make sure that buyers understand the time commitment they are making when buying an animal, help with puppy training, and provide pure bred papers for the animal within 6 months of purchase. 

References

https://www.ckc.ca/en

https://www.purebreddog.ca/why-choose-a-purebred-dog/

https://www.akc.org/expert-advice/dog-breeds/10-reasons-im-going-to-buy-a-purebred-dog/

       If your "pure bred" dog does not come with papers it is not a pure bred dog. All pure bred dogs are registered with a Kennel Club, usually of their country of residence. These Kennel Clubs provide papers to the owner of a dog certifying that it is pure bred. If you do not have papers you either did not buy a pure bred or did not read the purchase contract carefully enough and do not have full ownership. You as the buyer are not responsible for this paperwork, the breeder is. It is illegal in Canada for a CKC breeder to charge an extra fee to provide these papers or withhold them if a dog has been purchased. The breeder has 6 months to provide these papers to the new owners. It is against the CKC code of practice to sell to a pet store, so if you purchase an animal from a pet store it is highly unlikely that it is pure bred. 

References 

https://www.ckc.ca/en/Files/Legal-Policy-and-Procedures/Code-of-Practice-Sept-2017

https://www.ckc.ca/CanadianKennelClub/media/Documents/Bylaws/301-01-05WEB2022.pdf

https://www.purebreddog.ca/what-do-papers-look-like/