While the breed's Manx bloodline originated from the Isle of Man, the long-haired variant is claimed to have been developed by Canada.

According to the Isle of Man records, the taillessness trait of the Manx (and ultimately the Cymric) began as a mutation among the island's domestic cat population.

Long-haired kittens had been born to Manx cats on the Isle of Man, but had always been discarded by breeders as "mutants".

The International Cat Association (TICA)[9] recognizes the Cymric as a variety of Manx, not a separate breed with its own standards.

[4] The Cymric is a muscular, compact, medium to large cat with a sturdy bone structure, but the lack of a tail can make them appear small.

[4] The Cymric cat's coat is notably long and voluminous around the ruff, extending downward to create a shirtfront.

[4] Additionally, the coat extends onto the upper portion of the hindquarters above the hock, creating breeches,[4] a term derived from the visual effect of a cat's fur replicating traditional, baggy knee-length pants.

[12] The genetic mutation that gives both the Cymric and Manx their unusual tails is also responsible for other health complications like spina bifida, a spinal defect that can result in neurological issues whether that is difficult with movement or waste elimination.

genetic research, both the ACF and (less stringently) the GCCF impose special breeding restrictions on Manx cats (including the Cymric, however named and classified), for animal welfare reasons.