Dog crossbreed

Dog crossbreeds (sometimes called designer dogs) are dogs which have been crossbred or selectively bred from two or more recognized dog breeds. Generally considered a specific type of mixed-breed dog,^[1][2] dog crossbreeds are not recognised as breeds in their own right, and do not necessarily breed true. However, historic crossbreeding has led to established breeds, such as the Cesky Terrier.

Dog crossbreeds are combinations of lineages of the domestic dog; they are distinguished from canid hybrids, which are interspecific crosses between Canis species (wolves, coyotes, jackals, etc.).

Several types of working dog crossbreeds date from the 14th century or earlier, such as the lurcher or the longdog.

Historically, crosses between dogs of different types were more well accepted at a time when modern purebred breeds (based on the eugenics principles) did not yet exist.^[3][4] These types of crosses were performed to aggregate qualities of two different types in the same dog or to perfect an already fixed type of dog, always for working purposes.^[4] An example to be cited is the famous case of Lord Orford's Greyhounds, which were improved by adding courage through the crossing with Old English Bulldogs, achieving the desired result after six generations.^[5][4] With the success of Lord Orford's dogs, the practice was adopted by other Greyhound breeders and became more common.

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  Greyhound/Old English Bulldog first cross
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  Greyhound/Old English Bulldog second cross
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  Greyhound/Old English Bulldog third cross
• 
  Greyhound/Old English Bulldog fourth cross

Crossbreeding has played a key characteristic in the development of sled dogs with various crossbreeds developing to meet the specific needs of the era and geographical region, including the Mackenzie River husky, in which European breeds were crossed with Native American dogs to produce a powerful and hardy freighting dog in the 19th century, and the Alaskan husky, bred specifically for sled dog racing.^[6] In the 1980s, a rise in Nordic-style sled racing in Scandinavia, characterized by shorter distances than typically seen in North American sled racing, led to the development of the eurohound and greyster, crosses utilizing German shorthair pointers with Alaskan huskies and greyhounds, respectively.^[7] While the Mackenzie River husky has been largely replaced by mechanized travel, Alaskan huskies continue to be the most commonly used type of dog for competitive sled dog racing today.^[8][9]

Other historical examples are the bull and terrier (Old English Bulldog and terrier cross) and crosses between foxhounds and Old Spanish Pointers^[4] that later resulted in the English Pointer.

The Encyclopædia Britannica traces what was the "designer dog" fad to the late 20th century when breeders began to cross purebred Poodles with other purebred breeds to obtain a dog with the Poodle's hypoallergenic coat, along with various desirable characteristics from other breeds.^[10]

Los cachorros resultantes reciben nombres compuestos por sílabas (o sonidos) de los nombres de las razas de sus padres de pura raza, como Schnoodle ( cruce de Schnauzer y Caniche) ^{[ 10 ]} o Shepsky ( cruce de Pastor Alemán y Husky Siberiano ). Otras razas de pura raza se cruzan para crear perros de diseño con una infinidad de nombres inventados, como el Puggle (cruce de Pug y Beagle). Incluso hay cruces complejos (con múltiples razas en su ascendencia reciente) que se etiquetan de esta manera, como el German Chusky ( cruce de Pastor Alemán, Husky Siberiano y Chow Chow ) .

Al igual que ocurre con los hijos en una familia, un porcentaje de perros mestizos con la misma ascendencia racial se parecerán entre sí, aunque el cruce de razas no dé como resultado un fenotipo tan uniforme como el de los perros de raza pura. A menudo, incluso los cachorros de la misma camada tendrán un aspecto bastante diferente.

Otra característica definitoria de los perros de diseño es que suelen criarse como perros de compañía y mascotas . Los perros de trabajo y caza, cruzados deliberadamente para un propósito laboral específico, generalmente no reciben nombres compuestos; se les suele denominar por un nombre de tipo, como eurohounds (perros de trineo de carreras) o lurchers (perros de caza). Estos perros podrían considerarse solo como mestizos, no como animales de diseño, ya que la apariencia no es la razón principal de su cría. Una excepción a esto es el Labradoodle , que, aunque tiene un nombre compuesto, se utiliza a menudo como perro guía o de asistencia ^{[ 11 ] [ 12 ]} , además de ser un perro familiar popular.

Although designer dogs are often selected by owners for their novelty, reputable breeders sometimes use crossbreeding in an attempt to reduce the incidence of certain hereditary problems found in the purebred dogs, while retaining their more appealing traits. Jon Mooallem, writing in The New York Times, commented, "Given the roughly 350 inherited disorders littering the dog genome, crossing two purebreds and expanding their gene pools can be 'a phenomenally good idea,' according to one canine geneticist—if it is done conscientiously."^[13] Crossbreeding has not been well studied in dogs, although it has been for livestock. The heritability of the desired trait being bred for (such as a hypoallergenic coat) needs to be known; "Heritability is the proportion of the measurable difference observed between animals for a given trait that is due to genetics (and can be passed to the next generation)."^[14] In addition, the goals of dog crossbreeding may be harder to define than the goals of livestock crossbreeding; good temperament may be harder to define and measure than high calf weight.

Designer dog breeders are often criticized for being more interested in profitable puppy production than in dog health and welfare. Wally Conron, writing in Reader's Digest, comments on the popularity of crosses after his introduction of the Labradoodle: "Were breeders bothering to check their sires and bitches for heredity faults, or were they simply caught up in delivering to hungry customers the next status symbol?"^[15]

'Designer dog' puppies sometimes bring higher prices than the purebreds from which they are bred.^{[16][17][18][19]}Fanciers of designer dogs say that all modern dog breeds were created from earlier breeds and types of dogs through the same kind of selective breeding that is used to create designer dogs. Most of the modern breeds have ancestries that include various older dog types and breeds.

Crossbreeding that takes advantage of the increased chance that a recessive detrimental allele will only be inherited from one parent and therefore not expressed in the phenotype of the offspring,^[20] is one strategy breeders can use to decrease the incidences of genetic defects.

Some crossbred dogs, created by breeding two purebred dogs of different breeds, may have the advantage of heterosis, or crossbreed vigor. This advantage can be progressively diluted when two crossbreeds are bred in the attempt to create a breed, narrowing the gene pool. The best way to continue taking advantage of crossbreed vigor is from the breeding of dogs of purebred ancestry, as this vigor is typically seen only in the first generation cross of two purebred animals of separate breeds, thus taking advantage of genetic diversity.^[21]

Health of crossbred dogs depends on their being descended from healthy parents. However, studies of longevity in dogs have found some advantage for crossbreeds compared to purebred dogs.^[22] Crossbred dogs "have a far lower chance of exhibiting the disorders that are common with the parental breeds. Their genetic health will be substantially higher."^[23]

Despite commonly believed to be substantially healthier than pedigree dogs, data from clinical records of over 1,000 veterinary hospitals in the US shows the difference in life expectancy between mixed breed dogs and pedigree dogs to be minimal.^[24] A review of cemetery data in Japan found that the Shiba Inu had a life expectancy greater than crossbreeds; however crossbreeds still had a higher life expectancy than the average pedigree dog in this study.^[25] A Swedish study reviewing over 200,000 dogs registered for a veterinary insurance company in 1995 and 1996 found morbidity to be higher in most pedigrees than mongrels; however several pedigree breeds had a lower morbidity these are in order of highest risk to lowest risk: Drever, Norwegian Buhund, Schillerstövare, Jämthund, Gråhund, Siberian Husky, Karelian Bear Dog, Smaland Hound, Finnish Spitz, and Norrbottenspets. Notably all the breeds are native to the Scandinavian peninsula and are most commonly used as working dogs.^[26]

Some health issues not common in either parent breed may be more common in the crossbreed than both of the parent breeds. Prolapsed nictitating membrane gland is a condition more common in the Puggle and Jug than both of the parent breeds, which shows the complexity of genetics and provides evidence against the theory of hybrid vigour. Overall designer dog breeds had lower rates of PNMG.^[27]

Los perros mestizos no son reconocidos por los registros de razas tradicionales, incluso si ambos padres son de raza pura. Asociaciones como el American Kennel Club , el United Kennel Club y el Canadian Kennel Club no reconocen los cruces de diseño como razas caninas.

Si se crían perros mestizos durante un tiempo y su cría está bien documentada, eventualmente podrían ser reconocidos como una nueva raza por los principales clubes caninos (un ejemplo de un mestizo reciente que se ha convertido en una raza reconocida por todos los principales clubes caninos es el Cesky Terrier ). Las nuevas razas de perros deben tener un club de raza que documente la ascendencia de cada miembro individual de esa raza a partir de los perros fundadores originales; cuando el club canino al que el club de raza desea unirse esté satisfecho con el pedigrí de los perros, los aceptará y registrará. Cada club canino tiene sus propias reglas sobre cómo documentar una nueva raza. Algunos registros menores y empresas de registro en internet registran perros como cualquier raza que el propietario elija con documentación mínima o ninguna; algunos incluso permiten que el criador o propietario invente un "nombre de raza" para su mascota.

• Cruce , para cualquier animal
• tipo perro
• Feist
• Lista de razas de perros mestizos
• criadero de cachorros
• perro de raza pura

• Mooallem, Jon (4 de febrero de 2007). "El dilema de las perreras modernas" . The New York Times Magazine .
• Mucho ruido y pocas nueces sobre las heces en canismajor.com