In biological terms, a “cross-breed” typically refers to the mating of two different species, a process known as interspecies hybridization. The domestic cat, Felis catus, can successfully produce offspring with certain wild cat species, but this ability is limited to those that share a recent common ancestor. The success of any such pairing is governed by strict genetic compatibility, which determines if the resulting hybrid offspring will be viable and, more importantly, fertile. The vast majority of animals, including most other feline species, are separated from the domestic cat by insurmountable biological barriers.
Interbreeding Between Domestic Cat Breeds
The simplest form of feline crossing occurs entirely within the domestic cat population, which includes all recognized breeds. All these breeds belong to the single species Felis catus, meaning they can interbreed freely without biological impediment. The offspring of two different domestic cat breeds are simply referred to as mixed-breed cats, often called “moggies” in some regions.
This pairing is not considered interspecies hybridization because the parents are members of the same species. The resulting kittens are fully fertile and can reproduce themselves, continuing the genetic line. This genetic fluidity explains the wide variety of coat colors, patterns, and body types seen in the domestic cat population.
Domestic Cats and Wild Cat Species
Successful cross-breeding between domestic cats and wild cats is a rare event, generally limited to species closely related to Felis catus. The most successful pairings occur with smaller wild cats that belong to the Felis genus or closely allied genera, such as the African Serval (Leptailurus serval) and the Asian Leopard Cat (Prionailurus bengalensis). These species share a recent evolutionary history with the domestic cat, which allows for the initial fertilization and development of a hybrid fetus.
Crossing domestic cats with larger or more distantly related wild felids, such as bobcats, cougars, lions, or tigers, is biologically impossible. The genetic distance between these groups is too great, preventing the formation of a viable embryo. Even among closely related species, successful mating is often difficult and requires human intervention, as the wild cats may view the domestic cat as prey or a rival.
The Genetic Barrier to Cross-Breeding
The primary obstacle to interspecies hybridization is the difference in genetic structure. Domestic cats and many of their wild relatives, including the Serval and Asian Leopard Cat, share the same number of chromosomes, which is 38. This identical chromosome count is a prerequisite for successful pairing, as it allows the chromosomes from each parent to align during the formation of reproductive cells.
Despite the matching number, slight structural differences in the chromosomes prevent perfect alignment in the hybrid offspring. This misalignment leads to hybrid sterility, which is a major biological barrier. Specifically, the male offspring of the first generation (F1) cross are almost universally sterile, a pattern predicted by a genetic principle called Haldane’s Rule. The female F1 hybrids, however, are typically fertile and can be bred back to a domestic cat to continue the hybrid line.
Another significant barrier is the difference in gestation periods between the parent species. The domestic cat has a gestation period of approximately 65 days, while the Serval’s is around 74 days. When a domestic cat carries a hybrid fetus, the mismatch in developmental timing can lead to premature birth, stillbirths, or the need for intensive care to keep the kittens alive. These biological hurdles demonstrate why successful, fertile interspecies crosses are the exception rather than the rule.
Notable Hybrid Cat Breeds
The successful, intentional crossing of domestic cats with wild species has resulted in several recognized hybrid breeds. The Bengal cat, for example, originated from a cross with the Asian Leopard Cat and is prized for its distinctive spotted coat pattern. The Savannah cat is the result of breeding with the African Serval, known for its large size and striking spotted coats. A third example is the Chausie, developed by crossing the domestic cat with the Jungle Cat (Felis chaus).
In these hybrid breeds, the degree of wild ancestry is tracked using a filial generation system, denoted by the letter ‘F’ followed by a number. An F1 cat is the direct offspring of a domestic cat and a wild cat, possessing 50% wild genetics. Because F1 males are sterile, breeders must use fertile female hybrids and breed them back to domestic males. Fertility in the male line is typically regained by the fourth or fifth generation (F4 or F5), allowing the cats to be recognized as a domestic breed.